Patent ID: 12191099

DETAILED DESCRIPTION OF THE INVENTION

Known fused disconnects are subject to a number of problems in use. For example, any attempt to remove the fuse while the fuses are energized and under load may result in hazardous conditions because dangerous arcing may occur between the fuses and the fuse holder terminals. Some fuseholders designed to accommodate, for example, UL (Underwriters Laboratories) Class CC fuses and IEC (International Electrotechnical Commission) 10×38 fuses that are commonly used in industrial control devices include permanently mounted auxiliary contacts and associated rotary cams and switches to provide early-break and late-make voltage and current connections through the fuses when the fuses are pulled from fuse clips in a protective housing. One or more fuses may be pulled from the fuse clips, for example, by removing a drawer from the protective housing. Early-break and late-make connections are commonly employed, for example, in motor control applications. While early-break and late-make connections may increase the safety of such devices to users when installing and removing fuses, such features increase costs, complicate assembly of the fuseholder, and are undesirable for switching purposes.

Structurally, the early-break and late-make connections can be intricate and may not withstand repeated use for switching purposes. In addition, when opening and closing the drawer to disconnect or reconnect circuitry, the drawer may be inadvertently left in a partly opened or partly closed position. In either case, the fuses in the drawer may not be completely engaged to the fuse terminals, thereby compromising the electrical connection and rendering the fuseholder susceptible to unintended opening and closing of the circuit. Especially in environments subject to vibration, the fuses may be jarred loose from the clips. Still further, a partially opened drawer protruding from the fuseholder may interfere with workspace around the fuseholder. Workers may unintentionally bump into the opened drawers, and perhaps unintentionally close the drawer and re-energize the circuit.

Additionally, in certain systems, such as industrial control systems, electrical equipment has become standardized in size and shape, and because known fused disconnect switches tend to vary in size and shape from the standard norms, they are not necessarily compatible with power distribution panels utilized with such equipment. For at least the above reasons, use of fused disconnect switches have not completely met the needs of certain end applications.

FIG.1is a perspective view of an exemplary fusible switching disconnect device100that overcomes the aforementioned difficulties. The fusible switching disconnect device100may be conveniently switched on and off in a convenient and safe manner without interfering with workspace around the device100. The disconnect device100may reliably switch a circuit on and off in a cost effective manner and may be used with standardized equipment in, for example, industrial control system applications. Further, the disconnect device100may be provided with various mounting and connection options for versatility in the field. Various embodiments will be described below to demonstrate the versatility of the disconnect device, and it is contemplated that the disconnect device100may be beneficial in a variety of electrical circuits and applications. The embodiments set forth below are therefore provided for illustrative purposes only, and the invention is not intended to be limited to any specific embodiment or to any specific application.

In the illustrative embodiment ofFIG.1, the disconnect device100may be a two pole device formed from two separate disconnect modules102. Each module102may include an insulative housing104, a fuse106loaded into the housing104, a fuse cover or cap108attaching the fuse to the housing104, and a switch actuator110. The modules102are single pole modules, and the modules102may be coupled or ganged together to form the two pole disconnect device100. It is contemplated, however, that a multi-pole device could be formed in a single housing rather than in the modular fashion of the exemplary embodiment shown inFIG.1.

The housing104may be fabricated from an insulative or nonconductive material, such as plastic, according to known methods and techniques, including but not limited to injection molding techniques. In an exemplary embodiment, the housing104is formed into a generally rectangular size and shape which is complementary to and compatible with DIN and IEC standards applicable to standardized electrical equipment. In particular, for example, each housing104has lower edge112, opposite side edges114, side panels116extending between the side edges114, and an upper surface118extending between the side edges114and the side panels116. The lower edge112has a length L and the side edges114have a thickness T, such as 17.5 mm in one embodiment, and the length L and thickness T define an area or footprint on the lower edge112of the housing104. The footprint allows the lower edge112to be inserted into a standardized opening having a complementary shape and dimension. Additionally, the side edges114of the housing104have a height H in accordance with known standards, and the side edges114include slots120extending therethrough for ventilating the housing104. The upper surface118of the housing104may be contoured to include a raised central portion122and recessed end portions124extending to the side edges114of the housing104.

The fuse106of each module102may be loaded vertically in the housing104through an opening in the upper surface118of the housing104, and the fuse106may extend partly through the raised central portion122of the upper surface118. The fuse cover108extends over the exposed portion of the fuse106extending from the housing104, and the cover108secures the fuse106to the housing104in each module102. In an exemplary embodiment, the cover108may be fabricated from a non-conductive material, such as plastic, and may be formed with a generally flat or planar end section126and elongated fingers128extending between the upper surface118of the raised central portion122of the housing104and the end of the fuse106. Openings are provided in between adjacent fingers128to ventilate the end of the fuse106.

In an exemplary embodiment, the cover108further includes rim sections130joining the fingers128opposite the end section126of the cover108, and the rim sections130secure the cover108to the housing104. In an exemplary embodiment, the rim sections130cooperate with grooves in the housing104such that the cover108may rotate a predetermined amount, such as 25 degrees, between a locked position and a release position. That is, once the fuse106is inserted into the housing104, the fuse cover108may be installed over the end of the fuse106into the groove of the housing104, and the cover108may be rotated 25 degrees to the locked position wherein the cover108will frustrate removal of the fuse106from the housing104. The groove may also be ramped or inclined such that the cover108applies a slight downward force on the fuse106as the cover108is installed. To remove the fuse106, the cover108may be rotated from the locked position to the open position wherein both the cover108and the fuse106may be removed from the housing104.

The switch actuator110may be located in an aperture132of the raised upper surface122of the housing104, and the switch actuator110may partly extend through the raised upper surface122of the housing104. The switch actuator110may be rotatably mounted to the housing104on a shaft or axle134within the housing104, and the switch actuator110may include a lever, handle or bar136extending radially from the actuator110. By moving the lever136from a first edge138to a second edge140of the aperture132, the shaft134rotates to an open position that electrically disconnects the fuse106in each module102as explained below. When the lever136is moved from the second edge140to the first edge138, the shaft134rotates back to the closed position illustrated inFIG.1and electrically connects the fuse106.

A line side terminal element may142extend from the lower edge112of the housing104in each module102for establishing line and load connections to circuitry. As shown inFIG.1, the line side terminal element142is a bus bar clip configured or adapted to connect to a line input bus, although it is contemplated that other line side terminal elements could be employed in alternative embodiments. A panel mount clip144also extends from the lower edge112of the housing104to facilitate mounting of the disconnect device100on a panel.

FIG.2is a side elevational view of one of the disconnect modules102shown inFIG.1with the side panel116removed. The fuse106may be seen situated in a compartment150inside the housing104. In an exemplary embodiment, the fuse106may be a cylindrical cartridge fuse including an insulative cylindrical body152, conductive ferrules or end caps154coupled to each end of the body152, and a fuse element or fuse element assembly extending within the body152and electrically connected to the end caps154. In exemplary embodiments, the fuse106may be a UL Class CC fuse, a UL supplemental fuse, or an IEC 10×38 fuses which are commonly used in industrial control applications. These and other types of cartridge fuses suitable for use in the module102are commercially available from Eaton's Bussmann Business of St. Louis, Missouri. It is understood that other types of fuses may also be used in the module102as desired.

A lower conductive fuse terminal156may be located in a bottom portion of the fuse compartment150and may be U-shaped in one embodiment. One of the end caps154of the fuse106rests upon an upper leg158of the lower terminal156, and the other end cap154of the fuse106is coupled to an upper terminal160located in the housing104adjacent the fuse compartment150. The upper terminal160is, in turn, connected to a load side terminal162to accept a load side connection to the disconnect module102in a known manner. The load side terminal162in one embodiment is a known saddle screw terminal, although it is appreciated that other types of terminals could be employed for load side connections to the module102. Additionally, the lower fuse terminal156may include fuse rejection features in a further embodiment which prevent installation of incorrect fuse types into the module102.

The switch actuator110may be located in an actuator compartment164within the housing104and may include the shaft134, a rounded body166extending generally radially from the shaft134, the lever136extending from the body166, and an actuator link168coupled to the actuator body166. The actuator link168may be connected to a spring loaded contact assembly170including first and second movable or switchable contacts172and174coupled to a sliding bar176. In the closed position illustrated inFIG.2, the switchable contacts172and174are mechanically and electrically engaged to stationary contacts178and180mounted in the housing104. One of the stationary contacts178may be mounted to an end of the terminal element142, and the other of the stationary contacts180may be mounted to an end of the lower fuse terminal156. When the switchable contacts172and174are engaged to the stationary contacts178and180, a circuit is path completed through the fuse106from the line terminal142and the lower fuse terminal156to the upper fuse terminal160and the load terminal162.

While in an exemplary embodiment the stationary contact178is mounted to a terminal142having a bus bar clip, another terminal element, such as a known box lug or clamp terminal could be provided in a compartment182in the housing104in lieu of the bus bar clip. Thus, the module102may be used with a hard-wired connection to line-side circuitry instead of a line input bus. Thus, the module102is readily convertible to different mounting options in the field.

When the switch actuator110is rotated about the shaft134in the direction of arrow A, the siding bar176may be moved linearly upward in the direction of arrow B to disengage the switchable contacts172and174from the stationary contacts178and180. The lower fuse terminal156is then disconnected from the line-side terminal element while the fuse106remains electrically connected to the lower fuse terminal156and to the load side terminal162. An arc chute compartment184may be formed in the housing104beneath the switchable contacts172and174, and the arc chute may provide a space to contain and dissipate arcing energy as the switchable contacts172and174are disconnected. Arcing is broken at two locations at each of the contacts172and174, thus reducing arc intensity, and arcing is contained within the lower portions of the housing104and away from the upper surface118and the hands of a user when manipulating the switch actuator110to disconnect the fuse106from the line side terminal142.

The housing104additionally may include a locking ring186which may be used cooperatively with a retention aperture188in the switch actuator body166to secure the switch actuator110in one of the closed position shown inFIG.2and the open position shown inFIG.3. A locking pin for example, may be inserted through the locking ring186and the retention aperture188to restrain the switch actuator110in the corresponding open or closed position. Additionally, a fuse retaining arm could be provided in the switch actuator110to prevent removal of the fuses except when the switch actuator110is in the open position.

FIG.3illustrates the disconnect module102after the switch actuator has been moved in the direction of Arrow A to an open or switched position to disconnect the switchable contacts172and174from the stationary contacts178and180. As the actuator is moved to the open position, the actuator body166rotates about the shaft134and the actuator link168is accordingly moved upward in the actuator compartment164. As the link168moves upward, the link168pulls the sliding bar176upward in the direction of arrow B to separate the switchable contacts172and174from the stationary contacts178and180.

A bias element200may be provided beneath the sliding bar176and may force the sliding bar176upward in the direction of arrow B to a fully opened position separating the contacts172,174and178,180from one another. Thus, as the actuator body166is rotated in the direction of arrow A, the link168is moved past a point of equilibrium and the bias element200assists in opening of the contacts172,174and178,180. The bias element200therefore prevents partial opening of the contacts172,174and178,180and ensures a full separation of the contacts to securely break the circuit through the module102.

Additionally, when the actuator lever136is pulled back in the direction of arrow C to the closed position shown inFIG.2, the actuator link168is moved to position the sliding bar176downward in the direction of arrow D to engage and close the contacts172,174and178,180and reconnect the circuit through the fuse106. The sliding bar176is moved downward against the bias of the bias element200, and once in the closed position, the sliding bar176, the actuator link168and the switch actuator are in static equilibrium so that the switch actuator110will remain in the closed position.

In one exemplary embodiment, and as illustrated inFIGS.2and3, the bias element200may be a helical spring element which is loaded in compression in the closed position of the switch actuator110. It is appreciated, however, that in an alternative embodiment a coil spring could be loaded in tension when the switch actuator110is closed. Additionally, other known bias elements could be provided to produce opening and/or closing forces to assist in proper operation of the disconnect module102. Bias elements may also be utilized for dampening purposes when the contacts are opened.

The lever136, when moved between the opened and closed positions of the switch actuator110, does not interfere with workspace around the disconnect module102, and the lever136is unlikely to be inadvertently returned to the closed position from the open position. In the closed position shown inFIG.3, the lever136is located adjacent to an end of the fuse106. The fuse106therefore partly shelters the lever136from inadvertent contact and unintentional actuation to the closed position. The bias element200further provides some resistance to movement of the lever136and closing of the contact mechanism. Additionally, the stationary contacts178and180are at all times protected by the housing104of the module102, and any risk of electrical shock due to contact with line side terminal142and the stationary contacts178and180is avoided. The disconnect module102is therefore considered to be safer than many known fused disconnect devices.

When the modules102are ganged together to form a multi-pole device, such as the device100, one lever136may be extended through and connect to multiple switch actuators110for different modules. Thus, all the connected modules102may be disconnected and reconnected by manipulating a single lever136. That is, multiple poles in the device100may be switched simultaneously. Alternatively, the switch actuators110of each module102in the device100may be actuated independently with separate levers136for each module.

FIG.4is a side elevational view of a further exemplary embodiment of a fusible switching disconnect module102including, for example, a retractable lockout tab210which may extend from the switch actuator110when the lever136is moved to the open position. The lockout tab210may be provided with a lock opening212therethrough, and a padlock or other element may be inserted through the lock opening212to ensure that the lever136may not be moved to the closed position. In different embodiments, the lockout tab210may be spring loaded and extended automatically, or may be manually extended from the switch actuator body166. When the lever136is moved to closed position, the lockout tab210may be automatically or manually returned to retracted position wherein the switch actuator110may be rotated back to the closed position shown inFIG.2.

FIG.5is a perspective view of a third exemplary embodiment of a fusible switching disconnect module220similar to the module102described above but having, for example, a DIN rail mounting slot222formed in a lower edge224of a housing226. The housing226may also include openings228which may be used to gang the module220to other disconnect modules. Side edges230of the housing226may include connection openings232for line side and load connections to box lugs or clamps within the housing226. Access openings234may be provided in recessed upper surfaces236of the housing226. A stripped wire, for example, may be extended through the connection openings232and a screwdriver may be inserted through the access openings234to connect line and load circuitry to the module220.

Like the module102, the module220may include the fuse106, the fuse cover108and the switch actuator110. Switching of the module220is accomplished with switchable contacts as described above in relation to the module102.

FIGS.6and7are perspective views of a fourth exemplary embodiment of a fusible switching disconnect module250which, like the modules102and220described above, includes a switch actuator110rotatably mounted to the housing on a shaft134, a lever136extending from the shaft134, an actuator link168, and a slider bar176. The module250also includes, for example, a mounting clip144and a line side terminal element142.

Unlike the modules102and220, the module250may include a housing252configured or adapted to receive a rectangular fuse module254instead of a cartridge fuse106. The fuse module254is a known assembly including a rectangular housing256, and terminal blades258extending from the housing256. A fuse element or fuse assembly may be located within the housing256and is electrically connected between the terminal blades258. Such fuse modules254are known and in one embodiment are CUBEFuse modules commercially available from Eaton's Bussmann Business of St. Louis, Missouri.

A line side fuse clip260may be situated within the housing252and may receive one of the terminal blades258of the fuse module254. A load side fuse clip262may also be situated within the housing252and may receive the other of the fuse terminal blades258. The line side fuse clip260may be electrically connected to the stationary contact180. The load side fuse clip262may be electrically connected to the load side terminal162. The line side terminal142may include the stationary contact178, and switching may be accomplished by rotating the switch actuator110to engage and disengage the switchable contacts172and174with the respective stationary contacts178and180as described above. While the line terminal142is illustrated as a bus bar clip, it is recognized that other line terminals may be utilized in other embodiments, and the load side terminal162may likewise be another type of terminal in lieu of the illustrated saddle screw terminal in another embodiment.

The fuse module254may be plugged into the fuse clips260,262or extracted therefrom to install or remove the fuse module254from the housing252. For switching purposes, however, the circuit is connected and disconnected at the contacts172,174and178and180rather than at the fuse clips260and262. Arcing between the disconnected contacts may therefore contained in an arc chute or compartment270at the lower portion of the compartment and away from the fuse clips260and262. By opening the disconnect module250with the switch actuator110before installing or removing the fuse module254, any risk posed by electrical arcing or energized metal at the fuse and housing interface is eliminated. The disconnect module250is therefore believed to be safer to use than many known fused disconnect switches.

A plurality of modules250may be ganged or otherwise connected together to form a multi-pole device. The poles of the device could be actuated with a single lever136or independently operable with different levers.

FIG.8is a perspective view of a fifth exemplary embodiment of a fusible switching disconnect device300which is, for example, a multi-pole device in an integrated housing302.

The housing302may be constructed to accommodate three fuses106in an exemplary embodiment, and is therefore well suited for a three phase power application. The housing302may include a DIN rail slot304in the illustrated embodiment, although it is understood that other mounting options, mechanisms, and mounting schemes may be utilized in alternative embodiments. Additionally, in one embodiment the housing302may have a width dimension D of about 45 mm in accordance with IEC industry standards for contactors, relays, manual motor protectors, and integral starters that are also commonly used in industrial control system applications. The benefits of the invention, however, accrue equally to devices having different dimensions and devices for different applications.

The housing302may also include connection openings306and access openings308in each side edge310which may receive a wire connection and a tool, respectively, to establish line and load connections to the fuses106. A single switch actuator110may be rotated to connect and disconnect the circuit through the fuses between line and load terminals of the disconnect device300.

FIG.9is a perspective view of an exemplary switching assembly320for the device300. The switching assembly320may be accommodated in the housing302and in an exemplary embodiment may include a set of line terminals322, a set of load terminals324, a set of lower fuse terminals326associated with each respective fuse106, and a set of slider bars176having switchable contacts mounted thereon for engaging and disengaging stationary contacts mounted to the ends of the line terminals322and the lower fuse terminals324. An actuator link (not visible inFIG.9) may be mounted to an actuator shaft134, such that when the lever136is rotated, the slider bar176may be moved to disconnect the switchable contacts from the stationary contacts. Bias elements200may be provided beneath each of the slider bars176and assist operation of the switch actuator110as described above. As with the foregoing embodiments of modules, a variety of line side and load side terminal structures may be used in various embodiments of the switching assembly.

Retention bars328may also be provided on the shaft134which extend to the fuses106and engage the fuses in an interlocking manner to prevent the fuses106from being removed from the device300except when the switch actuator110is in the open position. In the open position, the retention bars328may be angled away from the fuses106and the fuses106may be freely removed. In the closed position, as shown inFIG.9, the retention arms or bars328lock the fuses106in place. In an exemplary embodiment, distal ends of the bars or arms328may be received in slots or detents in the fuses106, although the fuses106could be locked in another manner as desired.

FIG.10is a perspective view of a sixth exemplary embodiment of a fusible switching disconnect device370including the disconnect module300described above and, for example, an under voltage module372mounted to one side of the module300and mechanically linked to the switch mechanism in the module300. In an exemplary embodiment, the under voltage module372may include an electromagnetic coil374calibrated to a predetermined voltage range. When the voltage drops below the range, the electromagnetic coil374causes the switch contacts in the module300to open. A similar module372could be employed in an alternative embodiment to open the switch contacts when the voltage experienced by the electromagnetic coil374exceeds a predetermined voltage range, and may therefore serve as an overvoltage module. In such a manner, the switch contact in the module300could be opened with module372and the coil374as undervoltage or overvoltage conditions occur.

FIG.11is a perspective view of a seventh exemplary embodiment of a fusible switching disconnect device400which is essentially the disconnect device300and a disconnect device220coupled together. The disconnect device300provides three poles for an AC power circuit and the device220provides an additional pole for other purposes.

FIG.12is a perspective view of an eighth embodiment of a fusible switching disconnect module410that, like the foregoing embodiments, includes a nonconductive housing412, a switch actuator414extending through a raised upper surface415of the housing412, and a cover416that provides access to a fuse receptacle (not shown inFIG.12) within the housing412for installation and replacement of an overcurrent protection fuse (also not shown inFIG.12). Like the foregoing embodiments, the housing412includes switchable and stationary contacts (not shown inFIG.12) that complete or break an electrical connection through the fuse in the housing412via movement of an actuator lever417.

A DIN rail mounting slot418may be formed in a lower edge420of the housing412, and the DIN rail mounting slot418may be dimensioned, for example, for snap-fit engagement and disengagement with a 35 mm DIN rail by hand and without a need of tools. The housing412may also include openings422that may be used to gang the module410to other disconnect modules as explained below. Side edges424of the housing412may be open ended to provide access to wire lug terminals426to establish line and load-side electrical connections external circuitry. Terminal access openings428may be provided in recessed upper surfaces430of the housing412. A stripped wire, for example, may be extended through the sides of the wire lug terminals426and a screwdriver may be inserted through the access openings428to tighten a terminal screw to clamp the wires to the terminals426and connect line and load circuitry to the module410. While wire lug terminals426are included in one embodiment, it is recognized that a variety of alternative terminal configurations or types may be utilized in other embodiments to establish line and load side electrical connections to the module410via wires, cables, bus bars etc.

Like the foregoing embodiments, the housing412is sized and dimensioned complementary to and compatible with DIN and IEC standards, and the housing412defines an area or footprint on the lower edge420for use with standardized openings having a complementary shape and dimension. By way of example only, the housing412of the single pole module410may have a thickness T of about 17.5 mm for a breaking capacity of up to 32 A; 26 mm for a breaking capacity of up to 50 A, 34 mm for a breaking capacity of up to 125 A; and 40 mm for a breaking capacity of up to 150 A per DIN Standard 43 880. Likewise, it is understood that the module410could be fabricated as a multiple pole device such as a three pole device having a dimension T of about 45 mm for a breaking capacity of up to 32 A; 55 mm for a breaking capacity of up to 50 A, and 75 mm for a breaking capacity of up to 125 A. While exemplary dimensions are provided, it is understood that other dimensions of greater or lesser values may likewise be employed in alternative embodiments of the invention.

Additionally, and as illustrated inFIG.12, the side edges424of the housing412may include opposed pairs of vertically oriented flanges432spaced from one another and projecting away from the wire lug terminals426adjacent the housing upper surface430and the sides of the wire lug terminals426. The flanges432, sometimes referred to as wings, provide an increased surface area of the housing412in a horizontal plane extending between the between the wire lug terminals426on the opposing side edges424of the housing412than would otherwise occur if the flanges432were not present. That is, a peripheral outer surface area path length extending in a plane parallel to the lower surface420of the housing412includes the sum of the exterior surface dimensions of one of the pairs of flanges432extending from one of the terminals426, the exterior dimensions of the respective front or rear panel431,433of the housing, and the exterior surface dimensions of the opposing flanges432extending to the opposite terminal426.

Additionally, the housing412may also include horizontally extending ribs or shelves434spaced from one another and interconnecting the innermost flanges432in a lower portion of the housing side edges424. The ribs or shelves434increase a surface area path length between the terminals426in a vertical plane of the housing412to meet external requirements for spacing between the terminals426. The flanges432and ribs434result in serpentine-shaped surface areas in horizontal and vertical planes of the housing412that permit greater voltage ratings of the device without increasing the footprint of the module410in comparison, for example, to the previously described embodiments ofFIGS.1-11. For example, the flanges432and the ribs434, facilitate a voltage rating of 600 VAC while meeting applicable internal and external spacing requirements between the terminals426under applicable UL standards.

The cover416, unlike the above-described embodiments, may include a substantially flat cover portion436, and an upstanding finger grip portion438projecting upwardly and outwardly from one end of the flat cover portion436and facing the switch actuator414. The cover416may be fabricated from a nonconductive material or insulative material such as plastic according to known techniques, and a the flat cover portion436may be hinged at an end thereof opposite the finger grip portion438so that the cover portion436is pivotal about the hinge. By virtue of the hinge, the finger grip portion438is movable away from the switch actuator414along an arcuate path as further explained below. As illustrated inFIG.12, the cover416is in a closed position concealing the fuse within the housing412, and as explained below, the cover416is movable to an open position providing access to the fuse in the disconnect module410.

FIG.13is a side elevational view of the module410with the front panel431(FIG.12) removed so that internal components and features may be seen. The wire lug terminals426and terminal screws440are positioned adjacent the side edges424of the housing412. A fuse442is loaded or inserted into the module410in a direction substantially perpendicular to the housing upper surface415, and as illustrated inFIG.13, a longitudinal axis441of the fuse442extends vertically, as opposed to horizontally, within the housing412. The fuse442is contained within the housing412beneath the cover416, and more specifically beneath the flat cover portion436. The fuse442is situated longitudinally in a fuse receptacle437integrally formed in the housing412. That is, the fuse receptacle437is not movable relative to the housing402for loading and unloading of the fuse442. The fuse442is received in the receptacle437with one end of the fuse442positioned adjacent and beneath the cover416and the module top surface415and the other end of the fuse442spaced from the cover416and the module top surface415by a distance equal to the length of the fuse442. An actuator interlock443is formed with the cover416and extends downwardly into the housing412adjacent and alongside the fuse receptacle437. The actuator interlock443of the cover416extends opposite and away from the cover finger grip portion438.

A cover lockout tab444extends radially outwardly from a cylindrical body446of the switch actuator414, and when the switch actuator414is in the closed position illustrated inFIG.13completing an electrical connection through the fuse442, the cover lockout tab444is extended generally perpendicular to the actuator interlock443of the cover416and a distal end of the cover lockout tab444is positioned adjacent the actuator interlock443of the cover416. The cover lockout tab444therefore directly opposes movement of the actuator interlock443and resists any attempt by a user to rotate the cover416about the cover hinge448in the direction of arrow E to open the cover416. In such a manner, the fuse442cannot be accessed without first rotating the switch actuator414in the direction of arrow F to move the pair of switchable contacts450away from the stationary contacts452via the actuator link454and sliding bar456carrying the switchable contacts450in a similar manner to the foregoing embodiments. Inadvertent contact with energized portions of the fuse442is therefore prevented, as the cover416can only be opened to access the fuse442after the circuit through the fuse442is disconnected via the switchable contacts450, thereby providing a degree of safety to human operators of the module410. Additionally, and because the cover416conceals the fuse442when the switchable contacts450are closed, the outer surfaces of the housing412and the cover416are touch safe.

A conductive path through the housing412and fuse442is established as follows. A rigid terminal member458is extended from the load side terminal terminal426closest to the fuse442on one side of the housing412. A flexible contact member460, such as a wire may be connected to the terminal member458at one end and attached to an inner surface of the cover416at the opposite end. When the cover416is closed, the contact member460is brought into mechanical and electrical engagement with an upper ferrule or end cap462of the fuse442. A movable lower fuse terminal464is mechanically and electrically connected to the lower fuse ferrule or end cap466, and a flexible contact member468interconnects the movable lower fuse terminal464to a stationary terminal470that carries one of the stationary contacts452. The switchable contacts450interconnect the stationary contacts452when the switch actuator414is closed as shown inFIG.13. A rigid terminal member472completes the circuit path to the line side terminal426on the opposing side of the housing412. In use, current flows through the circuit path from the line side terminal426and the terminal member472, through the switch contacts450and452to the terminal member470. From the terminal member470, current flows through the contact member468to the lower fuse terminal464and through the fuse442. After flowing through the fuse442, current flows to the contact member460to the terminal member458and to the line side terminal426.

The fuse442in different exemplary embodiments may be a commercially available 10×38 Midget fuse of Eaton's Bussmann Business of St. Louis, Missouri; an IEC 10×38 fuse; a class CC fuse; or a D/DO European style fuse. Additionally, and as desired, optional fuse rejection features may be formed in the lower fuse terminal464or elsewhere in the module, and cooperate with fuse rejection features of the fuses so that only certain types of fuses may be properly installed in the module410. While certain examples of fuses are herein described, it is understood that other types and configurations of fuses may also be employed in alternative embodiments, including but not limited to various types of cylindrical or cartridge fuses and rectangular fuse modules.

A biasing element474may be provided between the movable lower fuse terminal464and the stationary terminal470. The bias element474may be for example, a helical coil spring that is compressed to provide an upward biasing force in the direction of arrow G to ensure mechanical and electrical engagement of the movable lower fuse terminal464to the lower fuse ferrule466and mechanical and electrical engagement between the upper fuse ferrule462and the flexible contact member460. When the cover416is opened in the direction of arrow E to the open position, the bias element474forces the fuse upward along its axis441in the direction of arrow G as shown inFIG.14, exposing the fuse442through the raised upper surface415of the housing412for easy retrieval by an operator for replacement. That is, the fuse442, by virtue of the bias element474, is automatically lifted and ejected from the housing412when the cover416is rotated about the hinge448in the direction of arrow E after the switch actuator414is rotated in the direction of arrow F.

FIG.15is a side elevational view of the module410with the cover416pivoted about the hinge448and the switch actuator414in the open position. The switchable contacts450are moved upwardly by rotation of the actuator414and the displacement of the actuator link454causes the sliding bar456to move along a linear axis475substantially parallel to the axis441of the fuse442, physically separating the switchable contacts450from the stationary contacts452within the housing412and disconnecting the conductive path through the fuse442. Additionally, and because of the pair of switchable contacts450, electrical arcing is distributed among more than one location as described above.

The bias element474deflects when the cover416is opened after the actuator414is moved to the open position, and the bias element474lifts the fuse442from the housing412so that the upper fuse ferrule462is extended above the top surface415of the housing. In such a position, the fuse442may be easily grasped and pulled out of or extracted from the module410along the axis441. Fuses may therefore be easily removed from the module410for replacement.

Also when the actuator414is moved to the open position, an actuator lockout tab476extends radially outwardly from the switch actuator body446and may accept for example, a padlock to prevent inadvertent closure of the actuator414in the direction of arrow H that would otherwise cause the slider bar456to move downward in the direction of arrow I along the axis475and engage the switchable contacts450to the stationary contacts452, again completing the electrical connection to the fuse442and presenting a safety hazard to operators. When desired, the cover416may be rotated back about the hinge448to the closed position shown inFIGS.12and13, and the switch actuator414may be rotated in the direction of arrow H to move the cover interlock tab444into engagement with the actuator interlock443of the cover416to maintain each of the cover416and the actuator414in static equilibrium in a closed and locked position. Closure of the cover416requires some force to overcome the resistance of the bias spring474in the fuse receptacle437, and movement of the actuator to the closed position requires some force to overcome the resistance of a bias element478associated with the sliding bar456, making inadvertent closure of the contacts and completion of the circuit through the module410much less likely.

FIG.16is a perspective view of a ganged arrangement of fusible switching disconnect modules410. Connector pieces480may be fabricated from plastic, for example, and may be used with the openings422in the housing panels to retain modules410in a side-by-side relation to one another with, for example, snap fit engagement. Pins482and/or shims484, for example, may be utilized to join or tie the actuator levers417and cover finger grip portions438of each module410to one another so that all of the actuator levers417and/or of all of the covers416of the combined modules410are simultaneously moved with one another. Simultaneous movement of the covers416and levers417may be especially advantageous for breaking three phase current or, as another example, when switching power to related equipment, such as motor and a cooling fan for the motor so that one does not run without the other.

While single pole modules410ganged to one another to form multiple pole devices has been described, it is understood that a multiple pole device having the features of the module410could be constructed in a single housing with appropriate modification of the embodiment shown inFIGS.8and9, for example.

FIG.17is a perspective view of a ninth embodiment of a fusible switching disconnect module500that, like the foregoing embodiments, includes a single pole housing502, a switch actuator504extending through a raised upper surface506of the housing502, and a cover508that provides access to a fuse receptacle (not shown inFIG.17) within the housing502for installation and replacement of an overcurrent protection fuse (also not shown inFIG.17). Like the foregoing embodiments, the housing502includes switchable and stationary contacts (not shown inFIG.17) that connect or disconnect an electrical connection through the fuse in the housing502via movement of an actuator lever510.

Similar to the module410, the module500may include a DIN rail mounting slot512formed in a lower edge514of the housing502for mounting of the housing502without a need of tools. The housing502may also include an actuator opening515providing access to the body of the switch actuator504so that the actuator504may be rotated between the open and closed positions in an automated manner and facilitate remote control of the module500. Openings516are also provided that may be used to gang the module500to other disconnect modules. A curved or arcuate tripping guide slot517is also formed in a front panel of the housing502. A slidable tripping mechanism, described below, is selectively positionable within the slot517to trip the module500and disconnect the current path therethrough upon an occurrence of predetermined circuit conditions. The slot517also provides access to the tripping mechanism for manual tripping of the mechanism with a tool, or to facilitate remote tripping capability.

Side edges518of the housing502may be open ended to provide access to line and load side wire lug terminals520to establish line and load-side electrical connections to the module500, although it is understood that other types of terminals may be used. Terminal access openings522may be provided in recessed upper surfaces524of the housing502to receive a stripped wire or other conductor extended through the sides of the wire lug terminals520, and a screwdriver may be inserted through the access openings522to connect line and load circuitry to the module500. Like the foregoing embodiments, the housing502is sized and dimensioned complementary to and compatible with DIN and IEC standards, and the housing502defines an area or footprint on the lower surface514of the housing for use with standardized openings having a complementary shape and dimension.

Like the module410described above, the side edges518of the housing502may include opposed pairs of vertically oriented flanges or wings526spaced from one another and projecting away from the wire lug terminals520adjacent the housing upper surface524and the sides of the wire lug terminals520. The housing502may also include horizontally extending ribs or shelves528spaced from one another and interconnecting the innermost flanges526in a lower portion of the housing side edges518. The flanges526and ribs528result in serpentine-shaped surface areas in horizontal and vertical planes of the housing502that permit greater voltage ratings of the device without increasing the footprint of the module500as explained above.

The cover508, unlike the above-described embodiments, may include a contoured outer surface defining a peak530and a concave section532sloping downwardly from the peak530and facing the switch actuator504. The peak530and the concave section532form a finger cradle area on the surface of the cover508and is suitable for example, to serve as a thumb rest for an operator to open or close the cover508. The cover508may be hinged at an end thereof closest to the peak530so that the cover508is pivotal about the hinge and the cover508is movable away from the switch actuator504along an arcuate path. As illustrated inFIG.17, the cover508is in a closed touch safe position concealing the fuse within the housing502, and as explained below, the cover508is movable to an open position providing access to the fuse.

FIG.18is a side elevational view of a portion of the fusible switching disconnect module500with a front panel thereof removed so that internal components and features may be seen. In some aspects the module500is similar to the module410described above in its internal components, and for brevity like features of the modules500and410are indicated with like reference characters inFIG.18.

The wire lug terminals520and terminal screws440are positioned adjacent the side edges518of the housing502. The fuse442is vertically loaded into the housing502beneath the cover508, and the fuse442is situated in the non-movable fuse receptacle437formed in the housing502. The cover508may be formed with a conductive contact member that may be, for example, cup-shaped to receive the upper fuse ferrule462when the cover508is closed.

A conductive circuit path is established from the line side terminal520and the terminal member472, through the switch contacts450and452to the terminal member470. From the terminal member470, current flows through the contact member468to the lower fuse terminal464and through the fuse442. After flowing through the fuse442, current flows from the conductive contact member542of the cover508to the contact member460connected to the conductive contact member542, and from the contact member460to the terminal member458and to the line side terminal426.

A biasing element474may be provided between the movable lower fuse terminal464and the stationary terminal470as described above to ensure mechanical and electrical connection between the cover contact member542and the upper fuse ferrule462and between the lower fuse terminal464and the lower fuse ferrule466. Also, the bias element474automatically ejects the fuse442from the housing502as described above when the cover508is rotated about the hinge448in the direction of arrow E after the switch actuator504is rotated in the direction of arrow F.

Unlike the module410, the module500may further include a tripping mechanism544in the form of a slidably mounted trip bar545and a solenoid546connected in parallel across the fuse442. The trip bar545is slidably mounted to the tripping guide slot517formed in the housing502, and in an exemplary embodiment the trip bar545may include a solenoid arm547, a cover interlock arm548extending substantially perpendicular to the solenoid arm547, and a support arm550extending obliquely to each of the solenoid arm547and cover interlock arm548. The support arm550may include a latch tab552on a distal end thereof. The body446of the switch actuator504may be formed with a ledge554that cooperates with the latch tab552to maintain the trip bar545and the actuator504in static equilibrium with the solenoid arm547resting on an upper surface of the solenoid546.

A torsion spring555is connected to the housing502one end and the actuator body446on the other end, and the torsion spring555biases the switch actuator504in the direction of arrow F to the open position. That is, the torsion spring555is resistant to movement of the actuator504in the direction of arrow H and tends to force the actuator body446to rotate in the direction of arrow F to the open position. Thus, the actuator504is failsafe by virtue of the torsion spring555. If the switch actuator504is not completely closed, the torsion spring555will force it to the open position and prevent inadvertent closure of the actuator switchable contacts450, together with safety and reliability issues associated with incomplete closure of the switchable contacts450relative to the stationary contacts452.

In normal operating conditions when the actuator504is in the closed position, the tendency of the torsion spring555to move the actuator to the open position is counteracted by the support arm550of the trip bar545as shown inFIG.18. The latch tab552of the support arm550engages the ledge554of the actuator body446and holds the actuator504stably in static equilibrium in a closed and locked position. Once the latch tab552is released from the ledge554of the actuator body446, however, the torsion spring555forces the actuator504to the open position.

An actuator interlock556is formed with the cover508and extends downwardly into the housing502adjacent the fuse receptacle437. The cover interlock arm548of the trip arm545is received in the actuator interlock556of the cover508and prevents the cover508from being opened unless the switch actuator504is rotated in the direction of arrow F as explained below to move the trip bar545and release the cover interlock arm548of the trip bar545from the actuator interlock556of the cover508. Deliberate rotation of the actuator504in the direction of arrow F causes the latch tab552of the support arm550of the trip bar545to be pivoted away from the actuator and causes the solenoid arm547to become inclined or angled relative to the solenoid546. Inclination of the trip bar545results in an unstable position and the torsion spring555forces the actuator504to rotate and further pivot the trip bar545to the point of release.

Absent deliberate movement of the actuator to the open position in the direction of arrow F, the trip bar545, via the interlock arm548, directly opposes movement of the cover508and resists any attempt by a user to rotate the cover508about the cover hinge448in the direction of arrow E to open the cover508while the switch actuator504is closed and the switchable contacts450are engaged to the stationary contacts452to complete a circuit path through the fuse442. Inadvertent contact with energized portions of the fuse442is therefore prevented, as the fuse can only be accessed when the circuit through the fuse is broken via the switchable contacts450, thereby providing a degree of safety to human operators of the module500.

Upper and lower solenoid contact members557,558are provided and establish electrical contact with the respective upper and lower ferrules462,466of the fuse442when the cover508is closed over the fuse442. The contact members557,558establish, in turn, electrical contact to a circuit board560. Resistors562are connected to the circuit board560and define a high resistance parallel circuit path across the ferrules462,466of the fuse442, and the solenoid546is connected to this parallel circuit path on the circuit board560. In an exemplary embodiment, the resistance is selected so that, in normal operation, substantially all of the current flow passes through the fuse442between the fuse ferrules462,466instead of through the upper and lower solenoid contact members557,558and the circuit board560. The coil of the solenoid546is calibrated so that when the solenoid546experiences a predetermined voltage, the solenoid generates an upward force in the direction of arrow G that causes the trip bar545to be displaced in the tripping guide slot517along an arcuate path defined by the slot517.

As those in the art may appreciate, the coil of the solenoid546may be calibrated to be responsive to a predetermined undervoltage condition or a predetermined overvoltage condition as desired. Additionally, the circuit board560may include circuitry to actively control operation of the solenoid546in response to circuit conditions. Contacts may further be provided on the circuit board560to facilitate remote control tripping of the solenoid546. Thus, in response to abnormal circuit conditions that are predetermined by the calibration of the solenoid coil or control circuitry on the board560, the solenoid546activates to displace the trip bar545. Depending on the configuration of the solenoid546and/or the board560, opening of the fuse442may or may not trigger an abnormal circuit condition causing the solenoid546to activate and displace the trip bar545.

As the trip bar545traverses the arcuate path in the guide slot517when the solenoid546operates, the solenoid arm547is pivoted and becomes inclined or angled relative to the solenoid546. Inclination of the solenoid arm547causes the trip bar545to become unstable and susceptible to force of the torsion spring555acting on the trip arm latch tab552via the ledge554in the actuator body446. As the torsion spring555begins to rotate the actuator504, the trip bar545is further pivoted due to engagement of the trip arm latch tab552and the actuator ledge554and becomes even more unstable and subject to the force of the torsion spring. The trip bar545is further moved and pivoted by the combined action of the guide slot517and the actuator504until the trip arm latch tab552is released from the actuator ledge554, and the interlock arm548of the trip bar545is released from the actuator interlock556. At this point, each of the actuator504and the cover508are freely rotatable.

FIG.19is a side elevational view of the fusible switching disconnect module500illustrating the solenoid546in a tripped position wherein a solenoid plunger570is displaced upwardly and engages the trip bar545, causing the trip bar545to move along the curved guide slot517and become inclined and unstable relative to the plunger. As the trip bar545is displaced and pivoted to become unstable, the torsion spring555assists in causing the trip bar545to become more unstable as described above, until the ledge554of the actuator body446is released from the latch tab552of the trip bar545, and the torsion spring555forces the actuator504to rotate completely to the open position shown inFIG.19. As the actuator504rotates to the open position, the actuator link454pulls the sliding bar456upward along the linear axis475and separates the switchable contacts450from the stationary contacts452to open or disconnect the circuit path between the housing terminals520. Additionally, the pivoting of the trip bar545releases the actuator interlock556of the cover508, allowing the bias element474to force the fuse upwardly from the housing502and causing the cover508to pivot about the hinge448so that the fuse442is exposed for easy removal and replacement.

FIG.20is a perspective view of the fusible switching disconnect module500in the tripped position and the relative positions of the actuator504, the trip bar545and the cover508. As also shown inFIG.20, the sliding bar456carrying the switchable contacts450may be assisted to the open position by a first bias element572external to the sliding bar456and a second bias element574internal to the sliding bar456. The bias elements572,574may be axially aligned with one another but oppositely loaded in one embodiment. The bias elements572,574may be for example, helical coil spring elements, and the first bias element572may be loaded in compression, for example, while the second bias element574is loaded in tension. Therefore, the first bias element572exerts an upwardly directed pushing force on the sliding bar456while the second bias element574exerts an upwardly directed pulling force on the sliding bar456. The combined forces of the bias elements572,574force the sliding bar in an upward direction indicated by arrow G when the actuator is rotated to the open position as shown inFIG.20. The double spring action of the bias elements572,574, together with the torsion spring555(FIGS.18and19) acting on the actuator504ensures a rapid, automatic, and complete separation of the switchable contacts450from the fixed contacts452in a reliable manner. Additionally, the double spring action of the bias elements572,574effectively prevents and/or compensates for contact bounce when the module500is operated.

AsFIG.20also illustrates, the actuator interlock556of the cover508is substantially U-shaped in an exemplary embodiment. As seen inFIG.21the interlock556extends downwardly into the housing502when the cover508is in the closed position over the fuse442, loading the bias element474in compression.FIG.22illustrates the cover interlock arm548of the trip bar545aligned with the actuator interlock556of the cover508when the cover508is in the closed position. In such a position, the actuator504may be rotated back in the direction of arrow H to move the sliding bar456downward in the direction of arrow I to engage the switchable contacts450to the stationary contacts452of the housing502. As the actuator504is rotated in the direction of arrow H, the trip bar545is pivoted back to the position shown inFIG.18, stably maintaining the actuator504in the closed position in an interlocked arrangement with the cover508. The trip bar545may be spring loaded to further assist the tripping action of the module500and/or the return of the trip bar545to the stable position, or still further to bias the trip bar545to a predetermined position with respect to the tripping guide slot517.

FIGS.23and24illustrate a tenth embodiment of a fusible switching disconnect device600including a disconnect module500and an auxiliary contact module602coupled or ganged to the housing502in a side-by-side relation to the module500via the openings516(FIG.17) in the module500.

The auxiliary contact module602may include a housing603generally complementary in shape to the housing502of the module500, and may include an actuator604similar to the actuator508of the module500. An actuator link606may interconnect the actuator604and a sliding bar608. The sliding bar608may carry, for example, two pairs of switchable contacts610spaced from another. One of the pairs of switchable contacts610connects and disconnects a circuit path between a first set of auxiliary terminals612and rigid terminal members614extending from the respective terminals612and each carrying a respective stationary contact for engagement and disengagement with the first set of switchable contacts610. The other pair of switchable contacts610connects and disconnects a circuit path between a second set of auxiliary terminals616and rigid terminal members618extending from the respective terminals616and each carrying a respective stationary contact for engagement and disengagement with the second set of switchable contacts610.

By joining or tying the actuator lever620of the auxiliary contact module602to the actuator lever510of the disconnect module500with a pin or a shim, for example, the actuator604of the auxiliary contact module602may be moved or tripped simultaneously with the actuator508of the disconnect module500. Thus, auxiliary connections may be connected and disconnected together with a primary connection established through the disconnect module500. For example, when the primary connection established through the module500powers an electric motor, an auxiliary connection to a cooling fan may be made to the auxiliary contact module via one of the sets of terminals612and616so that the fan and motor will be powered on and off simultaneously by the device600. As another example, one of the auxiliary connections through the terminals612and616of the auxiliary contact module602may be used for remote indication purposes to signal a remote device of the status of the device as being opened or closed to connect or disconnect circuits through the device600.

While the auxiliary contact features have been described in the context of an add-on module602, it is understood that the components of the module602could be integrated into the module500if desired. Single pole or multiple pole versions of such a device could likewise be provided.

FIGS.25-27illustrate an eleventh embodiment of a fusible switching disconnect device650including a disconnect module500and a monitoring module652coupled or ganged to the housing502of the module500via the openings516(FIG.17) in the module500.

The monitoring module652may include a housing654generally complementary in shape to the housing502of the module500. A sensor board656is located in the housing652, and flexible contact members658,660are respectively connected to each of the ferrules462,466(FIG.18) of the fuse442(FIG.1) in the disconnect module500via, for example, the upper and lower solenoid contact members557,558(FIG.18) that establish a parallel circuit path across the fuse ferrules462,466. The sensor board656includes a sensor662that monitors operating conditions of the contact members566,568and outputs a signal to an input/output element664powered by an onboard power supply such as a battery670. When predetermined operating conditions are detected with the sensor662, the input/output element664outputs a signal to a output signal port672or alternatively to a communications device674that wirelessly communicates with a remotely located overview and response dispatch system676that alerts, notifies, and summons maintenance personnel or responsible technicians to respond to tripping and opened fuse conditions to restore or re-energize associated circuitry with minimal downtime.

Optionally, an input signal port678may be included in the monitoring module652. The input signal port678may be interconnected with an output signal port672of another monitoring module, such that signals from multiple monitoring modules may be daisy chained together to a single communications device674for transmission to the remote system676. Interface plugs (not shown) may be used to interconnect one monitoring module to another in an electrical system.

In one embodiment, the sensor662is a voltage sensing latch circuit having first and second portions optically isolated from one another. When the primary fuse element680of the fuse442opens to interrupt the current path through the fuse, the sensor662detects the voltage drop across the terminal elements T1and T2(the solenoid contact members557and558) associated with the fuse442. The voltage drop causes one of the circuit portions, for example, to latch high and provide an input signal to the input/output element664. Acceptable sensing technology for the sensor662is available from, for example, SymCom, Inc. of Rapid City, South Dakota.

While in the exemplary embodiment, the sensor662is a voltage sensor, it is understood that other types of sensing could be used in alternative embodiments to monitor and sense an operating state of the fuse442, including but not limited to current sensors and temperature sensors that could be used to determine whether the primary fuse element680has been interrupted in an overcurrent condition to isolate or disconnect a portion of the associated electrical system.

In a further embodiment, one or more additional sensors or transducers682may be provided, internal or external to the monitoring module652, to collect data of interest with respect to the electrical system and the load connected to the fuse442. For example, sensors or transducers682may be adapted to monitor and sense vibration and displacement conditions, mechanical stress and strain conditions, acoustical emissions and noise conditions, thermal imagery and thermalography states, electrical resistance, pressure conditions, and humidity conditions in the vicinity of the fuse442and connected loads. The sensors or transducers682may be coupled to the input/output device664as signal inputs. Video imaging and surveillance devices (not shown) may also be provided to supply video data and inputs to the input/output element664.

In an exemplary embodiment, the input/output element664may be a microcontroller having a microprocessor or equivalent electronic package that receives the input signal from the sensor662when the fuse442has operated to interrupt the current path through the fuse442. The input/output element664, in response to the input signal from the sensor662, generates a data packet in a predetermined message protocol and outputs the data packet to the signal port672or the communications device674. The data packet may be formatted in any desirable protocol, but in an exemplary embodiment includes at least a fuse identification code, a fault code, and a location or address code in the data packet so that the operated fuse may be readily identified and its status confirmed, together with its location in the electrical system by the remote system676. Of course, the data packet could contain other information and codes of interest, including but not limited to system test codes, data collection codes, security codes and the like that is desirable or advantageous in the communications protocol.

Additionally, signal inputs from the sensor or transducer682may be input the input/output element664, and the input/output element664may generate a data packet in a predetermined message protocol and output the data packet to the signal port672or the communications device674. The data packet may include, for example, codes relating to vibration and displacement conditions, mechanical stress and strain conditions, acoustical emissions and noise conditions, thermal imagery and thermalography states, electrical resistance, pressure conditions, and humidity conditions in the vicinity of the fuse442and connected loads. Video and imaging data, supplied by the imaging and surveillance devices682may also be provided in the data packet. Such data may be utilized for troubleshooting, diagnostic, and event history logging for detailed analysis to optimize the larger electrical system.

The transmitted data packet from the communications device674, in addition to the data packet codes described above, also includes a unique transmitter identifier code so that the overview and response dispatch system676may identify the particular monitoring module652that is sending a data packet in a larger electrical system having a large number of monitoring modules652associated with a number of fuses. As such, the precise location of the affected disconnect module500in an electrical system may be identified by the overview and response dispatch system676and communicated to responding personnel, together with other information and instruction to quickly reset affected circuitry when one or more of the modules500operates to disconnect a portion of the electrical system.

In one embodiment, the communications device674is a low power radio frequency (RF) signal transmitter that digitally transmits the data packet in a wireless manner. Point-to-point wiring in the electrical system for fuse monitoring purposes is therefore avoided, although it is understood that point-to-point wiring could be utilized in some embodiments of the invention. Additionally, while a low power digital radio frequency transmitter has been specifically described, it is understood that other known communication schemes and equivalents could alternatively be used if desired.

Status indicators and the like such as light emitting diodes (LED's) may be provided in the monitoring module652to locally indicate an operated fuse442or a tripped disconnect condition. Thus, when maintenance personnel arrives at the location of the disconnect module500containing the fuse442, the status indicators may provide local state identification of the fuses associated with the module500.

Further details of such monitoring technology, communication with the remote system676, and response and operation of the system676are disclosed in commonly owned U.S. patent application Ser. No. 11/223,385 filed Sep. 9, 2005 and entitled Circuit Protector Monitoring Assembly, Kit and Method.

While the monitoring features have been described in the context of an add-on module652, it is understood that the components of the module652could be integrated into the module500if desired. Single pole or multiple pole versions of such a device could likewise be provided. Additionally, the monitoring module652and the auxiliary contact module could each be used with a single disconnect module500if desired, or alternatively could be combined in an integrated device with single pole or multiple pole capability.

FIG.28is a side elevational view of a portion of a twelfth embodiment of a fusible switching disconnect module700that is constructed similarly to the disconnect module500described above but includes a bimetallic overload element702in lieu of the solenoid described previously. The overload element702is fabricated from strips of two different types of metallic or conductive materials having different coefficients of thermal expansion joined to one another, and a resistance alloy joined to the metallic elements. The resistance alloy may be electrically isolated from the metallic strips with insulative material, such as a double cotton coating in an exemplary embodiment.

In use, the resistance alloy strip is joined to the contact members557and558and defines a high resistance parallel connection across the ferrules462and466of the fuse442. The resistance alloy is heated by current flowing through the resistance alloy and the resistance alloy, in turn heats the bimetal strip. When a predetermined current condition is approached, the differing rates of coefficients of thermal expansion in the bimetal strip cause the overload element702to bend and displace the trip bar545to the point of release where the spring loaded actuator504and sliding bar456move to the opened positions to disconnect the circuit through the fuse442.

The module700may be used in combination with other modules500or700, auxiliary contact modules602, and monitoring modules652. Single pole and multiple pole versions of the module700may also be provided.

FIG.29is a side elevational view of a portion of a thirteenth embodiment of a fusible switching disconnect module720that is constructed similarly to the disconnect module500described above but includes an electronic overload element722that monitors current flow through the fuse by virtue of the contact members557and558. When the current reaches a predetermined level, the electronic overload element722energizes a circuit to power the solenoid and trip the module720as described above. The electronic overload element722may likewise be used to reset the module after a tripping event.

The module702may be used in combination with other modules500or700, auxiliary contact modules602, and monitoring modules652. Single pole and multiple pole versions of the module700may also be provided.

Embodiments of fusible disconnect devices are therefore described herein that may be conveniently switched on and off in a convenient and safe manner without interfering with workspace around the device. The disconnect devices may be reliably switch a circuit on and off in a cost effective manner and may be used with standardized equipment in, for example, industrial control applications. Further, the disconnect modules and devices may be provided with various mounting and connection options for versatility in the field. Auxiliary contact and overload and underload tripping capability is provided, together with remote monitoring and control capability.

FIG.30is a side elevational view of a portion of a fourteenth embodiment of a fusible switching disconnect device750providing numerous additional benefits and advantages apart from those discussed above. Method aspects implementing advantageous features will be in part apparent and in part explicitly discussed in the description below.

The device750includes a disconnect housing752fabricated from an electrically nonconductive or insulative material such as plastic, and the fuse module housing752is configured or adapted to receive a retractable rectangular fuse module754. While a rectangular fuse module754is shown in the exemplary embodiment illustrated, it is recognized that the disconnect housing754may alternatively be configured to receive and engage another type of fuse, such as cylindrical or cartridge fuses familiar to those in the art and as described above. The disconnect housing752and its internal components described below, are sometimes referred to as a base assembly that receives the retractable fuse module754.

The fuse module754in the exemplary embodiment shown includes a rectangular housing756fabricated from an electrically nonconductive or insulative material such as plastic, and conductive terminal elements in the form of terminal blades758extending from the housing756. A primary fuse element or fuse assembly is located within the housing756and is electrically connected between the terminal blades758to provide a current path therebetween. Such fuse modules754are known and in one embodiment the rectangular fuse module is a CUBEFuse™ power fuse module commercially available from Eaton's Bussmann Business of St. Louis, Missouri. The fuse module754provides overcurrent protection via the primary fuse element therein that is configured to melt, disintegrate or otherwise fail and permanently open the current path through the fuse element between the terminal blades758in response to predetermined current conditions flowing through the fuse element in use. When the fuse element opens in such a manner, the fuse module754must be removed and replaced to restore affected circuitry.

A variety of different types of fuse elements, or fuse element assemblies, are known and may be utilized in the fuse module754with considerable performance variations in use. Also, the fuse module754may include fuse state indication features, a variety of which are known in the art, to identify the permanent opening of the primary fuse element such that the fuse module754can be quickly identified for replacement via a visual change in appearance when viewed from the exterior of the fuse module housing756. Such fuse state indication features may involve secondary fuse links or elements electrically connected in parallel with the primary fuse element in the fuse module754.

A conductive line side fuse clip760may be situated within the disconnect housing752and may receive one of the terminal blades758of the fuse module754. A conductive load side fuse clip762may also be situated within the disconnect housing752and may receive the other of the fuse terminal blades758. The line side fuse clip760may be electrically connected to a first line side terminal764provided in the disconnect housing752, and the first line side terminal764may include a stationary switch contact766. The load side fuse clip762may be electrically connected to a load side connection terminal768. In the example shown, the load side connection terminal768is a box lug terminal operable with a screw770to clamp or release an end of a connecting wire to establish electrical connection with load side electrical circuitry. Other types of load side connection terminals are known, however, and may be provided in alternative embodiments.

A rotary switch actuator772is further provided in the disconnect housing752, and is mechanically coupled to an actuator link774that, in turn, is coupled to a sliding actuator bar776. The actuator bar776carries a pair of switch contacts778and780. In an exemplary embodiment, the switch actuator772, the link774and the actuator bar778may be fabricated from nonconductive materials such as plastic. A second conductive line side terminal782including a stationary contact784is also provided, and a line side connecting terminal785is also provided in the disconnect housing752. In the example shown, the line side connection terminal785is a box lug terminal operable with a screw786to clamp or release an end of a connecting wire to establish electrical connection with line side electrical circuitry. Other types of line side connection terminals are known, however, and may be provided in alternative embodiments. While in the illustrated embodiment the line side connecting terminal785and the load side connecting terminal768are of the same type (i.e., both are box lug terminals), it is contemplated that different types of connection terminals could be provided on the line and load sides of the disconnect housing752if desired.

Electrical connection of the device750to power supply circuitry, sometimes referred to as the line side, may be accomplished in a known manner using the line side connecting terminal785. Likewise, electrical connection to load side circuitry may be accomplished in a known manner using the load side connecting terminal768. As mentioned previously, a variety of connecting techniques are known (e.g., spring clamp terminals and the like) and may alternatively be utilized to provide a number of different options to make the electrical connections in the field. The configuration of the connecting terminals785and768accordingly are exemplary only.

In the position shown inFIG.30, the disconnect device750is shown in the closed position with the switch contacts780and778mechanically and electrically engaged to the stationary contacts784and766, respectively. As such, and as further shown inFIG.33when the device750is connected to line side circuitry790with a first connecting wire792via the line side connecting terminal785, and also when the load side terminal768is connected to load side circuitry794with a connecting wire796, a circuit path is completed through conductive elements in the disconnect housing752and the fuse module754when the fuse module754is installed and when the primary fuse element therein is a non-opened, current carrying state.

Specifically, and referring again toFIGS.30and33, electrical current flow through the device750is as follows when the switch contacts778and780are closed, when the device750is connected to line and load side circuitry as shown inFIG.33, and when the fuse module754is installed. Electrical current flows from the line side circuitry790through the line side connecting wire792, and from the wire792to and through the line side connecting terminal785. From the line side connecting terminal785current then flows to and through the second line terminal782and to the stationary contact784. From the stationary contact784current flows to and through the switch contact780, and from the switch contact780current flows to and through the switch contact778. From the switch contact778current flows to and through the stationary contact766, and from the stationary contact766current flows to and through the first line side terminal764. From the first line side terminal764current flows to and through the line side fuse clip762, and from the line side fuse clip762current flows to and through the first mating fuse terminal blade758. From the first terminal blade758current flows to and through the primary fuse element in the fuse module754, and from the primary fuse element to and through the second fuse terminal blade758. From the second terminal blade758current flows to and through the load side fuse clip762, and from the load side fuse clip762to and through the load side connecting terminal768. Finally, from the connecting terminal768current flows to the load side circuitry794via the wire796(FIG.33). As such, a circuit path or current path is established through the device750that includes the fuse element of the fuse module754.

Disconnect switching to temporarily open the current path in the device750may be accomplished in multiple ways. First, and as shown inFIG.30, a portion of the switch actuator772projects through an upper surface of the disconnect housing752and is therefore accessible to be grasped for manual manipulation by a person. Specifically, the switch actuator772may be rotated from a closed position as shown inFIG.30to an open position in the direction of arrow A, causing the actuator link774to move the sliding bar776linearly in the direction of arrow B and moving the switch contacts780and778away from the stationary contacts784and766. Eventually, the switch contacts780and778become mechanically and electrically disengaged from the stationary contacts784and766and the circuit path between the first and second line terminals764and782, which includes the primary fusible element of the fuse module754, may be opened via the separation of the switch contacts780and778when the fuse terminal blades758are received in the line and load side fuse clips760and762.

When the circuit path in the device750is opened in such a manner via rotational displacement of the switch actuator772, the fuse module754becomes electrically disconnected from the first line side terminal764and the associated line side connecting terminal785. In other words, an open circuit is established between the line side connecting terminal785and the first terminal blade758of the fuse module754that is received in the line side fuse clip760. The operation of switch actuator772and the displacement of the sliding bar776to separate the contacts780and778from the stationary contacts784and766may be assisted with bias elements such as the springs described in embodiments above with similar benefits. Particularly, the sliding bar776may be biased toward the open position wherein the switch contacts780and778are separated from the contacts784and786by a predetermined distance. The dual switch contacts784and766mitigate electrical arcing concerns as the switch contacts784and766are engaged and disengaged.

Once the switch actuator772of the disconnect device750is switched open to interrupt the current path in the device750and disconnect the fuse module754, the current path in the device750may be closed to once again complete the circuit path through the fuse module754by rotating the switch actuator772in the opposite direction indicated by arrow C inFIG.30. As the switch actuator772rotates in the direction of arrow C, the actuator link774causes the sliding bar776to move linearly in the direction of arrow D and bring the switch contacts780and778toward the stationary contacts784and766to close the circuit path through the first and second line terminals764and782. As such, by moving the actuator772to a desired position, the fuse module754and associated load side circuitry794(FIG.33) may be connected and disconnected from the line side circuitry790(FIG.33) while the line side circuitry790remains “live” in an energized, full power condition. Alternatively stated, by rotating the switch actuator772to separate or join the switch contacts, the load side circuitry794may be electrically isolated from the line side circuitry790(FIG.33), or electrically connected to the line side circuitry794on demand.

Additionally, the fuse module754may be simply plugged into the fuse clips760,762or extracted therefrom to install or remove the fuse module754from the disconnect housing752. The fuse housing756projects from the disconnect housing752and is open and accessible from an exterior of the disconnect housing752so that a person simply can grasp the fuse housing756by hand and pull or lift the fuse module754in the direction of arrow B to disengage the fuse terminal blades758from the line and load side fuse clips760and762until the fuse module754is completely released from the disconnect housing752. An open circuit is established between the line and load side fuse clips760and762when the terminal blades758of the fuse module754are removed as the fuse module754is released, and the circuit path between the fuse clips760and762is completed when the fuse terminal blades758are engaged in the fuse clips760and762when the fuse module754is installed. Thus, via insertion and removal of the fuse module754, the circuit path through the device750can be opened or closed apart from the position of the switch contacts as described above.

Of course, the primary fuse element in the fuse module754provides still another mode of opening the current path through the device750when the fuse module is installed in response to actual current conditions flowing through the fuse element. As noted above, however, if the primary fuse element in the fuse module754opens, it does so permanently and the only way to restore the complete current path through the device750is to replace the fuse module754with another one having a non-opened fuse element. As such, and for discussion purposes, the opening of the fuse element in the fuse module754is permanent in the sense that the fuse module750cannot be reset to once again complete the current path through the device. Mere removal of the fuse module754, and also displacement of the switch actuator772as described, are in contrast considered to be temporary events and are resettable to easily complete the current path and restore full operation of the affected circuitry by once again installing the fuse module754and/or closing the switch contacts.

The fuse module754, or a replacement fuse module, can be conveniently and safely grasped by hand via the fuse module housing756and moved toward the switch housing752to engage the fuse terminal blades758to the line and load side fuse clips760and762. The fuse terminal blades758are extendable through openings in the disconnect housing752to connect the fuse terminal blades758to the fuse clips760and762. To remove the fuse module754, the fuse module housing756can be grasped by hand and pulled from the disconnect housing752until the fuse module754is completely released. As such, the fuse module754having the terminal blades758may be rather simply and easily plugged into the disconnect housing752and the fuse clips760,762, or unplugged as desired.

Such plug-in connection and removal of the fuse module754advantageously facilitates quick and convenient installation and removal of the fuse module754without requiring separately supplied fuse carrier elements and without requiring tools or fasteners common to other known fusible disconnect devices. Also, the fuse terminal blades758extend through and outwardly project from a common side of the fuse module body756, and in the example shown the terminal blades758each extend outwardly from a lower side of the fuse housing756that faces the disconnect housing752as the fuse module754is mated to the disconnect housing752.

In the exemplary embodiment shown, the fuse terminal blades758extending from the fuse module body756are generally aligned with one another and extend in respective spaced-apart parallel planes. It is recognized, however, that the terminal blades758in various other embodiments may be staggered or offset from one another, need not extend in parallel planes, and can be differently dimensioned or shaped. The shape, dimension, and relative orientation of the terminal blades758, and the receiving fuse clips760and762in the disconnect housing752may serve as fuse rejection features that only allow compatible fuses to be used with the disconnect housing752. In any event, because the terminal blades758project away from the lower side of the fuse housing756, a person's hand when handling the fuse module housing756for plug in installation (or removal) is physically isolated from the terminal blades758and the conductive line and load side fuse clips760and762that receive the terminal blades758as mechanical and electrical connections therebetween are made and broken. The fuse module754is therefore touch safe (i.e., may be safely handled by hand to install and remove the fuse module754without risk of electrical shock).

The disconnect device750is rather compact and occupies a reduced amount of space in an electrical power distribution system including the line side circuitry790and the load side circuitry794than other known fusible disconnect devices and arrangements providing similar effect. In the embodiment illustrated inFIG.30the disconnect housing752is provided with a DIN rail slot800that may be used to securely mount the disconnect housing752in place with snap-on installation to a DIN rail by hand and without tools. The DIN rail may be located in a cabinet or supported by other structure, and because of the smaller size of the device750, a greater number of devices750may be mounted to the DIN rail in comparison to conventional fusible disconnect devices.

In another embodiment, the device750may be configured for panel mounting by replacing the line side terminal785, for example, with a panel mounting clip. When so provided, the device750can easily occupy less space in a fusible panelboard assembly, for example, than conventional in-line fuse and circuit breaker combinations. In particular, CUBEFuse™ power fuse modules occupy a smaller area, sometimes referred to as a footprint, in the panel assembly than non-rectangular fuses having comparable ratings and interruption capabilities. Reductions in the size of panelboards are therefore possible, with increased interruption capabilities.

In ordinary use, the circuit path or current path through the device750is preferably connected and disconnected at the switch contacts784,780,778,766rather than at the fuse clips760and762. By doing so, electrical arcing that may occur when connecting/disconnecting the circuit path may be contained at a location away from the fuse clips760and762to provide additional safety for persons installing, removing, or replacing fuses. By opening the switch contacts with the switch actuator772before installing or removing the fuse module754, any risk posed by electrical arcing or energized conductors at the fuse and disconnect housing interface is eliminated. The disconnect device750is accordingly believed to be safer to use than many known fused disconnect switches.

The disconnect switching device750includes still further features, however, that improve the safety of the device750in the event that a person attempts to remove the fuse module754without first operating the actuator772to disconnect the circuit through the fuse module754, and also to ensure that the fuse module754is compatible with the remainder of the device750. That is, features are provided to ensure that the rating of the fuse module754is compatible with the rating of the conductive components in the disconnect housing752.

As shown inFIG.30, the disconnect housing752in one example includes an open ended receptacle or cavity802on an upper edge thereof that accepts a portion of the fuse housing756when the fuse module754is installed with the fuse terminal blades758engaged to the fuse clips760,762. The receptacle802is shallow in the embodiment depicted, such that a relatively small portion of the fuse housing756is received when the terminal blades758are plugged into the disconnect housing752. A remainder of the fuse housing756, however, generally projects outwardly from the disconnect housing752allowing the fuse module housing756to be easily accessed and grasped with a user's hand and facilitating a finger safe handling of the fuse module754for installation and removal without requiring tools. It is understood, however, that in other embodiments the fuse housing756need not project as greatly from the switch housing receptacle when installed as in the embodiment depicted, and indeed could even be substantially entirely contained within the switch housing752if desired.

In the exemplary embodiment shown inFIG.30, the fuse housing756includes a recessed guide rim804having a slightly smaller outer perimeter than a remainder of the fuse housing756, and the guide rim804is seated in the switch housing receptacle802when the fuse module754is installed. It is understood, however, that the guide rim804may be considered entirely optional in another embodiment and need not be provided. The guide rim804may in whole or in part serve as a fuse rejection feature that would prevent someone from installing a fuse module754having a rating that is incompatible with the conductive components in the disconnect housing752. Fuse rejection features could further be provided by modifying the terminal blades758in shape, orientation, or relative position to ensure that a fuse module having an incompatible rating cannot be installed.

In contemplated embodiments, the base of the device750(i.e., the disconnect housing752and the conductive components therein) has a rating that is ½ of the rating of the fuse module754. Thus, for example, a base having a current rating of 20 A may preferably be used with a fuse module754having a rating of 40 A. Ideally, however, fuse rejection features such as those described above would prevent a fuse module of a higher rating, such as 60 A, from being installed in the base. The fuse rejection features in the disconnect housing752and/or the fuse module754can be strategically coordinated to allow a fuse of a lower rating (e.g., a fuse module having a current rating of 20 A) to be installed, but to reject fuses having higher current ratings (e.g., 60 A and above in the example being discussed). It can therefore be practically ensured that problematic combinations of fuse modules and bases will not occur. While exemplary ratings are discussed above, they are provided for the sake of illustration rather than limitation. A variety of fuse ratings and base ratings are possible, and the base rating and the fuse module rating may vary in different embodiments and in some embodiments the base rating and the fuse module rating may be the same.

As a further enhancement, the disconnect housing752includes an interlock element806that frustrates any effort to remove the fuse module754while the circuit path through the first and second line terminals782and764via the switch contacts784,780,778,766is closed. The exemplary interlock element806shown includes an interlock shaft808at a leading edge thereof, and in the locked position shown inFIG.30the interlock shaft808extends through a hole in the first fuse terminal blade758that is received in the line side fuse clip760. Thus, as long as the projecting interlock shaft808is extended through the opening in the terminal blade758, the fuse module754cannot be pulled from the fuse clip762if a person attempts to pull or lift the fuse module housing756in the direction of arrow B. As a result, and because of the interlock element806, the fuse terminal blades758cannot be removed from the fuse clips760and762while the switch contacts are closed778,780are closed and potential electrical arcing at the interface of the fuse clips760and762and the fuse terminal blades758is avoided. Such an interlock element806is believed to be beneficial for the reasons stated but could be considered optional in certain embodiments and need not be utilized.

The interlock element806is coordinated with the switch actuator772so that the interlock element806is moved to an unlocked position wherein the first fuse terminal blade758is released for removal from the fuse clip760as the switch actuator772is manipulated to open the device750. More specifically, a pivotally mounted actuator arm810is provided in the disconnect housing752at a distance from the switch actuator772, and a first generally linear mechanical link812interconnects the switch actuator772with the arm810. The pivot points of the switch actuator772and the arm810are nearly aligned in the example shown inFIG.30, and as the switch actuator772is rotated in the direction of arrow A, the link812carried on the switch actuator772simultaneously rotates and causes the arm810to rotate similarly in the direction of arrow E. As such, the switch actuator772and the arm810are rotated in the same rotational direction at approximately the same rate.

A second generally linear mechanical link814is also provided that interconnects the pivot arm810and a portion of the interlock element806. As the arm810is rotated in the direction of arrow E, the link814is simultaneously displaced and pulls the interlock element806in the direction of arrow F, causing the projecting shaft808to become disengaged from the first terminal blade758and unlocking the interlock element806. When so unlocked, the fuse module754can then be freely removed from the fuse clips760and762by lifting on the fuse module housing756in the direction of arrow B. The fuse module754, or perhaps a replacement fuse module754, can accordingly be freely installed by plugging the terminal blades758into the respective fuse clips760and762.

As the switch actuator772is moved back in the direction of arrow C to close the disconnect device750, the first link812causes the pivot arm810to rotate in the direction of arrow G, causing the second link814to push the interlock element806in the direction of arrow H until the projecting shaft808of the interlock element806again passes through the opening of the first terminal blade758and assumes a locked position with the first terminal blade758. As such, and because of the arrangement of the arm810and the links812and814, the interlock element806is slidably movable within the disconnect housing752between locked and unlocked positions. This slidable movement of the interlock element806occurs in a substantially linear and axial direction within the disconnect housing752in the directions of arrow F and H inFIG.30.

In the example shown, the axial sliding movement of the interlock element806is generally perpendicular to the axial sliding movement of the actuator bar766that carries the switchable contacts778and780. In the plane ofFIG.30, the movement of the interlock element806occurs along a substantially horizontal axis, while the movement of the sliding bar776occurs along a substantially vertical axis. The vertical and horizontal actuation of the sliding bar776and the interlock element806, respectively, contributes to the compact size of the resultant device750, although it is contemplated that other arrangements are possible and could be utilized to mechanically move and coordinate positions of the switch actuator772, the switch sliding bar776and the interlock element806. Also, the interlock element806may be biased to assist in moving the interlock element to the locked or unlocked position as desired, as well as to resist movement of the switch actuator772, the sliding bar776and the interlock element806from one position to another. For example, by biasing the switch actuator772to the opened position to separate the switch contacts, either directly or indirectly via bias elements acting upon the sliding bar776or the interlock element806, inadvertent closure of the switch actuator772to close the switch contacts and complete the current path may be largely, if not entirely frustrated, because once the switch contacts are opened a person must apply a sufficient force to overcome the bias force and move the switch actuator772back to the closed position shown inFIG.30to reset the device750and again complete the circuit path. If sufficient bias force is present, it can be practically ensured that the switch actuator772will not be moved to close the switch via accidental or inadvertent touching of the switch actuator772.

The interlock element806may be fabricated from a nonconductive material such as plastic according to known techniques, and may be formed into various shapes, including but not limited to the shape depicted inFIG.30. Rails and the like may be formed in the disconnect housing752to facilitate the sliding movement of the interlock element806between the locked and unlocked positions.

The pivot arm810is further coordinated with a tripping element820for automatic operation of the device750to open the switch contacts778,780. That is, the pivot arm810, in combination a tripping element actuator described below, and also in combination with the linkage774,812, and814define a tripping mechanism to force the switch contacts778,780to open independently from the action of any person. Operation of the tripping mechanism is fully automatic, as described below, in response to actual circuit conditions, as opposed to the manual operation of the switch actuator772described above. Further, the tripping mechanism is multifunctional as described below to not only open the switch contacts, but to also to displace the switch actuator772and the interlock element806to their opened and unlocked positions, respectively. The pivot arm810and associated linkage may be fabricated from relatively lightweight nonconductive materials such as plastic.

In the example shown inFIG.30, the tripping element actuator820is an electromagnetic coil such as a solenoid having a cylinder or pin822, sometimes referred to as a plunger, that is extendable or retractable in the direction of arrow F and H along an axis of the coil. The coil when energized generates a magnetic field that causes the cylinder or pin822to be displaced. The direction of the displacement depends on the orientation of the magnetic field generated so as to push or pull the plunger cylinder or pin822along the axis of the coil. The plunger cylinder or pin822may assume various shapes (e.g., may be rounded, rectangular or have other geometric shape in outer profile) and may be dimensioned to perform as hereinafter described.

In the example shown inFIG.30, when the plunger cylinder or pin822is extended in the direction of arrow F, it mechanically contacts a portion of the pivot arm810and causes rotation thereof in the direction of arrow E. As the pivot arm810rotates, the link812is simultaneously moved and causes the switch actuator772to rotate in the direction of arrow A, which in turn pulls the link774and moves the sliding bar776to open the switch contacts778,780. Likewise, rotation of the pivot arm810in the direction of arrow E simultaneously causes the link814to move the interlock element806in the direction of arrow F to the unlocked position.

It is therefore seen that a single pivot arm810and the linkage812and814mechanically couples the switch actuator772and the interlock element806during normal operation of the device, and also mechanically couples the switch actuator772and the interlock element806to the tripping element820for automatic operation of the device. In the exemplary embodiment shown, an end of the link774connecting the switch actuator772and the sliding bar776that carries the switch contacts778,780is coupled to the switch actuator772at approximately a common location as the end of the link812, thereby ensuring that when the tripping element820operates to pivot the arm810, the link812provides a dynamic force to the switch actuator772and the link774to ensure an efficient separation of the contacts778and780with a reduced amount of mechanical force than may otherwise be necessary. The tripping element actuator820engages the pivot arm810at a good distance from the pivot point of the arm810when mounted, and the resultant mechanical leverage provides sufficient mechanical force to overcome the static equilibrium of the mechanism when the switch contacts are in the opened or closed position. A compact and economical, yet highly effective tripping mechanism is therefore provided. Once the tripping mechanism operates, it may be quickly and easily reset by moving the switch actuator772back to the closed position that closes the switch contacts.

Suitable solenoids are commercially available for use as the tripping actuator element820. Exemplary solenoids include LEDEX® Box Frame Solenoid Size B17M of Johnson Electric Group (www.ledex.com) and ZHO-0520L/S Open Frame Solenoids of Zohnen Electric Appliances (www.zonhen.com). In different embodiments, the solenoid820may be configured to push the arm810and cause it to rotate, or to pull the contact arm810and cause it to rotate. That is, the tripping mechanism can be operated to cause the switch contacts to open with a pushing action on the pivot arm810as described above, or with a pulling action on the pivot arm810. Likewise, the solenoid could operate on elements other than the pivot arm810if desired, and more than one solenoid could be provided to achieve different effects.

In still other embodiments, it is contemplated that actuator elements other than a solenoid may suitably serve as a tripping element actuator to achieve similar effects with the same or different mechanical linkage to provide comparable tripping mechanisms with similar benefits to varying degrees. Further, while simultaneous actuation of the components described is beneficial, simultaneous activation of the interlock element806and the sliding bar776carrying the switch contacts778,780may be considered optional in some embodiments and these components could accordingly be independently actuated and separately operable if desired. Different types of actuation could be provided for different elements.

Moreover, while in the embodiment shown, the trip mechanism is entirely contained within the disconnect housing752while still providing a relatively small package size. It is recognized, however, that in other embodiments the tripping mechanism may in whole or in part reside outside the disconnect housing752, such as in separately provided modules that may be joined to the disconnect housing752. As such, in some embodiments, the trip mechanism could be, at least in part, considered an optional add-on feature provided in a module to be used with the disconnect housing752. Specifically, the trip element actuator and linkage in a separately provided module may be mechanically linked to the switch actuator772, the pivot arm810and/or the sliding bar776of the disconnect housing752to provide comparable functionality to that described above, albeit at greater cost and with a larger overall package size.

The tripping element820and associated mechanism may further be coordinated with a detection element and control circuitry, described further below, to automatically move the switch contacts778,780to the opened position when predetermined electrical conditions occur. In one exemplary embodiment, the second line terminal782is provided with an in-line detection element830that is monitored by control circuitry850described below. As such, actual electrical conditions can be detected and monitored in real time and the tripping element820can be intelligently operated to open the circuit path in a proactive manner independent of operation of the fuse module754itself and/or any manual displacement of the switch actuator772. That is, by sensing, detecting and monitoring electrical conditions in the line terminal782with the detection element830, the switch contacts778,780can be automatically opened with the tripping element820in response to predetermined electrical conditions that are potentially problematic for either of the fuse module754or the base assembly (i.e., the disconnect housing752and its components).

In particular, the control circuitry850may open the switch contacts in response to conditions that may otherwise, if allowed to continue, cause the primary fuse element in the fuse module754to permanently open and interrupt the electrical circuit path between the fuse terminals758. Such monitoring and control may effectively prevent the fuse module754from opening altogether in certain conditions, and accordingly save it from having to be replaced, as well as providing notification to electrical system operators of potential problems in the electrical power distribution system. Beneficially, if permanent opening of the fuse is avoided via proactive management of the tripping mechanism, the device750becomes, for practical purposes, a generally resettable device that may in many instances avoid any need to locate a replacement fuse module, which may or may not be readily available if needed, and allow a much quicker restoration of the circuitry than may otherwise be possible if the fuse module754has to be replaced. It is recognized, however, that if certain circuit conditions were to occur, permanent opening of the fuse754may be unavoidable.

As shown inFIG.31, the detecting element830may be provided in the form of a low resistance shunt830that facilitates current sensing and measurement. The shunt830may be integrally provided in the line terminal782and provided for assembly of the disconnect device750as a single piece. In the example shown, the shunt830may be welded to a distal end832and a proximal end834of the terminal782. The connecting terminal785may likewise be integrally provided with the terminal782or may alternatively be separately attached. In exemplary embodiments, the shunt830may be a 100 or 200 micro Ohm shunt element. The shunt element is placed in-line (i.e. is electrically connected in series) with the current path in the line terminal782, rather than in a parallel current path (i.e., a path electrically connected in parallel with the circuit path established through the device750). In another embodiment, however, current may be detected along a parallel current path if desired, and used for control purposes in a similar manner to that described below.

FIG.32illustrates an exemplary first line terminal764for the device750shown inFIG.30. As shown inFIG.32, the first line terminal764includes the contact766at one end thereof, and an integrally formed fuse clip762. The fuse clip762is cut from a section836and shaped or bent into the configuration shown. A spring element838is further provided on the fuse clip762. While the integrally formed fuse clip762is beneficial from manufacturing and assembly perspectives, it is understood that the line side fuse clip762could alternatively be separately provided and attached to the remainder of the terminal if desired.

The terminals782and764shown inFIGS.31and32are examples only. Other terminal configurations are possible and may be used. It is understood that the shunt element830may be provided in the terminal764instead of the terminal782, or perhaps elsewhere in the device750, with similar effect.

As shown inFIGS.30,33and34the device750further includes a neutral terminal or neutral connection852that facilitates operation of processor-based electronic control circuitry850for control purposes. As seen inFIG.34, the line side circuitry790may be, for example, operating at 120 VAC. The control circuitry850may include, as shown inFIG.34a first circuit board854and a second circuit board856. The first circuit board854includes step down components and circuitry858and analog to digital conversion components and circuitry860such that the first board854may supply direct current (DC) power to the second board856at reduced voltage, such as 24 VDC. The first board is accordingly sometimes referred to as a power supply board854. Because the power supply board854draws power from the line side circuitry790operating at a higher voltage, the control circuitry850need not have an independent power supply, such as batteries and the like or a separately provided power line for the electronic circuitry that would otherwise be necessary. While exemplary input and output voltages for the power supply board are discussed, it is understood that other input and output voltages are possible and depend in part on specific applications of the device750in the field.

The second board856is sometimes referred to as a processing board. In the exemplary embodiment shown, the processing board856includes a processor-based microcontroller including a processor862and a memory storage864wherein executable instructions, commands, and control algorithms, as well as other data and information required to satisfactorily operate the disconnect device750are stored. The memory864of the processor-based device may be, for example, a random access memory (RAM), and other forms of memory used in conjunction with RAM memory, including but not limited to flash memory (FLASH), programmable read only memory (PROM), and electronically erasable programmable read only memory (EEPROM).

As used herein, the term “processor-based” microcontroller shall refer not only to controller devices including a processor or microprocessor as shown, but also to other equivalent elements such as microcomputers, programmable logic controllers, reduced instruction set (RISC) circuits, application specific integrated circuits and other programmable circuits, logic circuits, equivalents thereof, and any other circuit or processor capable of executing the functions described below. The processor-based devices listed above are exemplary only, and are thus not intended to limit in any way the definition and/or meaning of the term “processor-based”.

While the circuitry850is shown inFIG.33as residing internally to the disconnect housing752and is entirely contained therein, it could alternatively be provided in whole or in part outside the disconnect housing752, such as in separately provided modules that may be joined to the disconnect housing752. The detecting element830, while also shown as residing in the disconnect housing752, could likewise be provided outside the housing in a separately provided module that may or may not include the control circuitry850.

The detecting element830senses the line side current path in the first line terminal830and provides an input to the processing board856. Thus, the control circuitry850, by virtue of the detecting element830, is provided with real time information regarding current passing through the line terminal782. The detected current is then monitored and compared to a baseline current condition, such as a time-current curve as further explained below, that is programmed into the circuitry (e.g., stored in the memory864). By comparing the detected current with the baseline current, decisions can be made by the processor862, for example, to operate a trip mechanism866such as the tripping element actuator820and related linkage described above in response to predetermined electrical conditions as further described below.

As shown inFIGS.30,33and34the disconnect device750may further include an indicator element870in the disconnect housing752to signify certain electrical conditions as they occur or different states of the disconnect device750. The indicator870may be, for example, a light emitting diode (LED), although other types of indicators are known and may be used. In one embodiment, the LED indicator870is operable in more than one mode to distinctly indicate different electrical events. For example, a flashing or intermittent illumination of the indicator870may indicate an overcurrent condition in the circuitry that has not yet opened the primary fuse element of the fuse module754, while a solid or continuous non-intermittent illumination may indicate a trip event wherein the tripping mechanism866has caused the switch contacts778,780to open or to indicate an open fuse condition. Of course, other indication schemes are possible using one or more indicator elements, whether or not LEDs.

As also shown inFIG.34, a remote signal device880may be further connected as an input to the circuitry850, and may serve as an override element to cause the tripping mechanism866to operate independently of any detected condition by the element830. In one contemplated arrangement, the remote signal device880could generate a 24V input signal at the neutral terminal852. The remote signal device880may be a processor based, electronic device such as those described above or another device capable of providing the input signal. Using the remote signal device880, the disconnect device750may be remotely tripped on demand in response to circuit events upstream or downstream of the device, to perform maintenance procedures, or for still other reasons.

The remote signal device880may be especially useful for coordinating different loads that may be connected to the control circuitry. In one such example, the load794may include a motor and a separately powered fan provided to cool the motor in use. If the device750is connected in series with the motor but not the fan, and if the device750operates to open the switch contacts to the motor, the signal device880can be used to switch the fan off. Likewise, if the fan ceases to operate, a signal can be sent with the remote signal device880to open the switch contacts in the device750and disconnect the motor in the load circuitry794.

As further shown inFIGS.33and34, an overvoltage module890may be provided and may be electrically connected in parallel to the load side circuitry794. Specifically, the overvoltage module890may be connected to the load side connecting terminal768and electrical ground. The overvoltage module890in contemplated embodiments may include a voltage-dependent, nonlinear resistive element such as a metal oxide varistor element and may accordingly be configured as a transient voltage surge suppression device or surge suppression device. A varistor is characterized by having a relatively high resistance when exposed to a normal operating voltage, and a much lower resistance when exposed to a larger voltage, such as is associated with over-voltage conditions. The impedance of the current path through the varistor is substantially lower than the impedance of the circuitry being protected (i.e., the load side circuitry890) when the device is operating in the low-impedance mode, and is otherwise substantially higher than the impedance of the protected circuitry. As over-voltage conditions arise, the varistor switches from the high impedance mode to the low impedance mode and shunt or divert over-voltage-induced current surges away from the protected circuitry and to electrical ground, and as over-voltage conditions subside, the varistor returns to a high impedance mode. The varistor may switch to the low impedance mode much more rapidly than the fuse module754could act to open the circuit through the device150to the load794, and the over-voltage element890therefore protects the load side circuitry794from transient over-voltage events that the fuse itself may not protect against.

FIG.35is an exemplary time-current curve for exemplary fuse modules useable with the device750in various embodiments. The curve is plotted from or otherwise represents a multitude of data points for time and current values, and the corresponding time-current curve data can be programmed into the controller memory864in a look-up table, for example, and may therefore be used as a guideline comparison for actual current conditions detected with the element830. As shown inFIG.35, the time current curve is logarithmic and includes current magnitude values in amperes on the vertical axis, and time magnitude values in seconds on the horizontal axis. A number of fuse modules of different current ratings in amperes are plotted on the graph. The exemplary fuse modules plotted inFIG.35are Low-Peak® CUBEFuse® Finger Safe, Dual Element, Time Delay Class J performance fuses of Eaton's Bussmann Business, St. Louis, Missouri and having amperage ratings of 1-100 A. Such time-current curves are known and have been determined for many types of fuses, but to the extent not already determined such time-current curves could be empirically determined or theoretically established.

While multiple fuses are plotted in the example ofFIG.35, for any given base assembly for the device750(i.e., the disconnect housing752and its components) only one plot, or set of data corresponding to one of the plots, for the most appropriately rated fuse need be provided for the control circuitry850to operate. Of course, more than one set of data corresponding to different curves may be provided if desired, as long as the control circuitry utilizes the proper set of data for any fuse used with the device. Each set of data may represent an entire time-current curve as shown in the example ofFIG.35, or only a portion or range of one of the time-current curves depending on actual applications of the device of the field and electrical events of most interest.

It can be seen from the exemplary time-current curves ofFIG.35that any of the fuses plotted can withstand substantially greater currents than the corresponding rated current for some period of time before opening. For example, considering the plotted curve for the 40 A rated fuse, the fuse module can withstand current magnitude levels approaching 500 A for approximately 1 second before opening. However, the same 40 A fuse module can withstand about 80 A of current for about 100 seconds before opening, or between 50 and 60 A for 1000 seconds before opening. Especially for longer duration overcurrent events, the plot can serve as a guide for the control circuitry to cause the trip mechanism866to operate in response to current conditions sustained for a period of time that is not yet sufficient to open the fuse element in the module, but is perhaps symptomatic of a problem in the electrical system.

By virtue of the detection element830providing a control input signal, the control circuitry850can compare not only the magnitude of actual current flowing through the device750(and hence flowing through the fuse module754) at any given point in time, but can measure the duration of the current flow in order to make control decisions. That is, the control circuitry850is configured to make time-based and magnitude-based decisions by comparing elapsed duration of actual current conditions (i.e., actual levels of current) to the predetermined time-current curve expectation for the fuse in use with the device750. Based on the magnitude and time duration of detected electrical current conditions, the control circuitry850can intelligently monitor and control operation of the device750in response to current conditions actually detected before the fuse module754permanently opens.

For example, default rules can be implemented with the processor862to determine one or more time-based and magnitude-based tripping points causing the circuitry850to operate the tripping mechanism866in response to detected electrical current conditions. In one exemplary scenario, if detected current conditions reach 150% of the rated current of the fuse module754actually used in the device750for a predetermined amount of time, which may be a predetermined percentage of the time indicated in the time-current curve at the detected current level, the trip mechanism may be actuated. As such, the trip mechanism866may be actuated in anticipation of the fuse module754opening. Alternatively, stated, the control circuitry850may open the switch contacts with the tripping mechanism866, based on the time-current curve as compared to detected current durations, in less time than the fuse module754would otherwise take to operate and open the circuit through the device750. The tripping of the mechanism866under such circumstances, which can be indicated with the indicator870, may serve as a prompt to troubleshoot the electrical system to determine the cause of the overcurrent, if possible. Once the device750is tripped in such a fashion, the fuse module754may or may not need to be replaced, depending on how close the tripping points are to the actual opening points of the fuse based on the applicable time-current curve.

Likewise, tripping points can be set at a point higher than the time-current curve may otherwise indicate to ensure that the switch contacts in the device750are opened in the event that a fuse module754withstands a given current level for a duration longer than would be expected from the time-current curve. Thus, considering the exemplary time-current curve for the 40 A rated fuse inFIG.35, if a 40 A rated fuse module withstands an actual 60 A current as detected with the element830for a duration of 300 seconds, the control circuitry can decide to operate the tripping mechanism866because according to the time-current curve, the fuse would have been expected to operate and open at about 200 seconds, well prior to expiration of the 300 second period. Such a scenario could represent a condition wherein a fuse having an inappropriately high current rating has been installed, or perhaps an atypical performance of the fuse of the proper rating. In any event, the control circuitry850could emulate the performance of the properly rated fuse, or a more typically performing fuse of the proper rating, in such circumstances.

In accordance with the foregoing examples, the control circuitry850can respond to threshold deviations between actual detected current and the baseline current from the time-current curve, either directly or indirectly utilizing tripping points offset from the time-current curve. By monitoring time and current conditions, and by comparing actual current conditions to the time-current curve, and also with some strategic selection of the threshold tripping points, the control circuitry850can be tailored to different sensitivities for different applications, and may even detect unusual or unexpected operating conditions and accordingly trip the device750to prevent any associated damage to the load side circuitry794.

Of course, the comparison of detected time and current parameters to the predetermined time-current curve can confirm also an unremarkable or normal operating state of the fuse754and the device750. For example, a 40 A rated fuse could operate at a 40 A current level or below indefinitely without opening, and the control circuitry850would in such circumstances take no action to operate the trip mechanism866.

Having now described the control circuitry850functionally, it is believed those in the art could implement the functionality described with appropriate circuitry and appropriately programmed operating algorithms without further explanation.

FIG.36is a side elevational view of a portion of a fifteenth embodiment of a fusible switching disconnect device900that in many ways is similar to the device750described above, and hence like reference characters of the devices750and900are indicated with like reference characters in the Figures. Common features of the devices750and900will not be separately described herein, and the reader is referred back to the device750and the discussion above.

Unlike the device750, the device900has a different detecting element902. That is, the shunt element830is replaced with another and different type of detecting element902in the form of a Hall Effect sensor. As shown inFIG.37, the Hall Effect sensor902is integrally provided in the line terminal782having the stationary contact784. The Hall Effect sensor902may be used in lieu of the control element830to provide feedback to the control circuitry850described above to intelligently monitor and control the tripping mechanism866in a similar manner to that described above. An exemplary Hall Effect sensor suited for use as the detection element902includes an ACS758xCB Hall Effect-based sensor of Allegro MicroSystems, Inc., Worcester, Massachusetts.

As still another option, and as also shown inFIG.36, a current transformer910could be provided in lieu of or in addition to the Hall Effect sensor902to detect current flow and provide feedback to the control circuitry850. The current transformer910could be located interior or exterior to the device900in different embodiments. A suitable current transformer for use as the element910includes a CT1002 Current Transformer and a CT1281 Current Transformer available from Electroohms Pvt., Ltd., Banagalore, India.

While the control circuitry850described is responsive to current sensing using resistive shunts, Hall Effect sensors or current transformers providing control inputs to the circuitry850, similar functionality could be provided using sensor or detection elements corresponding to other electrical circuit conditions. For example, because voltage and current are linearly related, voltage sensing inputs could be used and current values could be readily calculated therefrom for use by the control circuitry850. Still further, voltage sensors could be used to make time-based and magnitude-based comparisons in a similar manner to those described above without first having to calculate current values. In such embodiments, time-current curves and data sets may be omitted in favor of other baseline curves or data sets, which may or may not be conversions of time-current curves, that may be used to directly or indirectly set time-based and magnitude-based threshold tripping points. As such, tripping points utilized by the control circuitry need not be derived from time-current curves, but can be established in light of other considerations for specific end uses or to meet different specifications.

The advantages and benefits of the invention are now believed to have been amply demonstrated in the exemplary embodiments disclosed.

An embodiment of a fusible switch disconnect device has been disclosed including: a disconnect housing adapted to receive and engage at least a portion of a removable electrical fuse, the fuse including first and second terminal elements and a fusible element electrically connected therebetween, the fusible element defining a circuit path and being configured to permanently open the circuit path in response to predetermined electrical current conditions experienced in the circuit path; line side and load side terminals in the disconnect housing and electrically connecting to the respective first and second terminal elements of the fuse when the fuse is received and engaged with the disconnect housing; at least one switchable contact in the disconnect housing, the at least one switchable contact provided between one of the line side terminal and load side terminal and a corresponding one of the first and second terminal elements of the fuse, the at least one switchable contact selectively positionable in an open position and a closed position to respectively connect or disconnect an electrical connection between the line side terminal and the load side terminal and through the circuit path of the fusible element; and a mechanism operable to automatically cause the at least one switchable contact to move to the open position in response to a predetermined electrical condition when the line side terminal is connected to energized line circuitry.

Optionally, the fusible switch disconnect device of claim may also include a detecting element configured to detect the predetermined electrical condition. The electrical condition may include one of a voltage condition and a current condition. In an embodiment wherein the electrical condition is a voltage condition, the detecting element may be configured to monitor one of an undervoltage condition and an overvoltage condition.

A microcontroller may be provided in communication with the detection element and the microcontroller may cause the mechanism to move the switchable contact in response to detection of the predetermined electrical condition. The microcontroller may be configured to compare an actual electrical condition as detected with the detection element to a baseline operating condition, and when the compared electrical condition deviates from the baseline electrical condition by a predetermined threshold, the microcontroller may operate the mechanism to move to the open position. The baseline operating condition may include a time-current curve.

As further options, the microcontroller may be provided on a first circuit board in the disconnect housing, with the fusible switch disconnect device further comprising a second circuit board in the disconnect housing, wherein the second circuit board supplies power to the first circuit board. The second circuit board may be connected to one of the line and load side terminals and may receive power therefrom. The second circuit board may be configured to receive AC power from one of the line and load side terminals and supply DC power to the first circuit board. The second circuit board may also be configured to step down the power supply from one of the line and load side terminals and supply the stepped down power to the first circuit board.

The mechanism may optionally include a solenoid, and the solenoid may be responsive to the microcontroller and cause displacement of the switchable contact from the closed position. The detecting element may be configured to sense current flow through the closed switchable contact, and may be one of a Hall Effect sensor, a current transformer, and a shunt. The detecting element may monitor a current path in the disconnect device at a location between the at least one switchable contact and one of the line and load side terminals.

A neutral connecting terminal may also be optionally provided in the fusible switch disconnect device, and the microcontroller may be electrically connected to the neutral terminal. An overvoltage detecting element may also optionally be provided, and the overvoltage detecting element may be connected between one of the line and load side terminals and the neutral terminal.

Also optionally, an indicator responsive to the microcontroller may further be provided to indicate the electrical condition. The indicator may be a light emitting diode. The indicator may further be operable in at least two distinct modes, including a continuous indication mode and an intermittent indication mode.

In an embodiment wherein the detecting element includes a resistive shunt, it may optionally be integrally provided in a conductive terminal element extending between the switchable contact and one of the line and load side terminals.

The at least one switchable contact in the fusible switch disconnect device may optionally include a pair of movable contacts, and the movable contacts may be biased to an open position. The fuse in the fusible switch disconnect device may include a rectangular fuse module having plug-in terminal blades engageable with the disconnect housing. The fuse may be directly receivable and engageable with the disconnect housing without utilizing a separately provided fuse carrier.

The mechanism in the fusible switch disconnect device may optionally include an electromagnetic coil including a cylinder extendable and retractable along an axis of the coil. A rotatable arm may be provided in the fusible switch disconnect device and may be positioned proximate the electromagnetic coil, wherein the rotatable arm may be displaced when the cylinder is extended.

Another embodiment of a fusible switch disconnect device has also been disclosed including: a disconnect housing adapted to receive and engage at least a portion of a removable electrical fuse, the fuse including first and second terminal elements and a fusible element electrically connected therebetween, the fusible element defining a circuit path and being configured to permanently open the circuit path in response to predetermined electrical current conditions experienced in the circuit path; at least a first terminal in the disconnect housing associated with the circuit path when the fuse when the fuse is received and engaged with the disconnect housing; at least one switchable contact in the disconnect housing and associated with the first terminal, the at least one switchable contact selectively positionable in an open position and a closed position to respectively connect or disconnect an electrical connection through the circuit path of the fusible element; and electronic circuitry configured to: monitor current flow through at least one of the first terminal and the circuit path of the fusible element; and compare the monitored current flow to a baseline operating condition, wherein the baseline operating condition comprises at least one set of time-current data associated with operation of the fuse.

Optionally, the disconnect housing may include a line side terminal and a load side terminal respectively engageable to the first and second terminal elements of the fuse, and the at least one switchable contact may include a first switchable contact provided on one of the line side and load side terminal. The fusible switch disconnect device may further include a line side connecting terminal and a load side connecting terminal respectively providing line side and load side connections to line and load electrical circuitry, and the at least one switchable contact may include a second switchable contact provided on one of the line and load side connecting terminals. A detecting element may be associated with one of the line and load side connecting terminals, and the detecting element may provide a signal input to the electronic circuitry, thereby allowing the current flow to be monitored. The detecting element may include at least one a resistive shunt, a current transformer, and a Hall Effect sensor.

Optionally, the fusible switch disconnect device of claim29, may further include a mechanism, responsive to the electronic circuitry, to automatically cause the at least one switchable contact to move to the open position if the compared monitored current flow deviates from the baseline operating condition by a predetermined amount. The mechanism may include a solenoid responsive to the electronic circuitry. The electronic circuitry may include a power supply board and a processing board.

A local state indicator may also optionally be provided, and may be configured to visually indicate a deviation of the monitored current flow to a baseline operating condition while the at least one switchable contact is in the closed position. The local state indicator may include a light emitting diode, and the electronic circuitry may cause the light emitting diode to flash intermittently to indicate the deviation.

The fusible switch disconnect device of claim may optionally further include a neutral terminal and a remote signal device in communication with the neutral terminal. An over-voltage detecting element may be coupled to the electronic circuitry, and the over-voltage detecting element may include a varistor element. The electronic circuitry may optionally include a microcontroller, and the removable electrical fuse may include a rectangular fuse module having plug-in terminal blades.

Another embodiment of a fusible switch disconnect device has also been disclosed, including: housing means for receiving an overcurrent protection fuse; terminal means for establishing a circuit path through the overcurrent protection fuse; switching means for connecting and disconnecting the circuit path; overcurrent detecting means for sensing electrical current flow in the circuit path; and controller means for making a time-based and magnitude-based comparison of sensed current flow versus a predetermined time-based and magnitude-based baseline for the overcurrent protection fuse.

A means for operating the switching means in response to the time-based and magnitude based comparison may further be optionally provided. An over-voltage detecting means for detecting an over-voltage condition in the circuit path may also be provided, and so may a remote signaling means for over-riding the controller means. Local indication means may be provided for indicating a deviation in the time-based and magnitude-based comparison.

An embodiment of a fusible switch disconnect device has likewise been disclosed including: a housing configured to receive a removable overcurrent protection fuse; terminals establishing a circuit path through the housing and the fuse when the fuse is received; a detecting element configured to sense an electrical condition in the circuit path; and a processor-based control element configured to undertake a time-based and magnitude-based comparison of the sensed electrical condition in the current path and a predetermined time-based and magnitude-based electrical condition baseline.

Optionally, the fusible switch disconnect device may also include switch contacts for connecting and disconnecting a portion of the circuit path, and the control element may cause automatic positioning of the switch contacts to disconnect the circuit path in response to the time-based and magnitude based comparison. The detecting element may be configured to sense current in the circuit path. The electrical condition baseline may include a set of current magnitude values and time values for each current magnitude level. The set of current magnitude values and time values may be derived from a time-current curve for the overcurrent protection fuse.

Also optionally, the electrical condition baseline may include at least one set of electrical condition magnitude values and time values for each electrical condition magnitude level, and the controller may position the switch contacts based on both the electrical condition magnitude values and the time values in the set. The data set may define at least a portion of a curve in a predefined relationship of the electrical current condition and a state of the overcurrent protection fuse. The predefined relationship may be a time-current curve. The overcurrent protection fuse may be configured for plug in electrical connection to complete the current path.

While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.'