Patent Description:
Fuses are widely used as overcurrent protection devices to prevent costly damage to electrical circuits. Fuse terminals typically form an electrical connection between an electrical power source and an electrical component or a combination of components arranged in an electrical circuit. One or more fusible links or elements, or a fuse element assembly, is connected between the fuse terminals, so that when electrical current through the fuse exceeds a predetermined limit, the fusible elements melt and open one or more circuits through the fuse to prevent electrical component damage.

A variety of fusible disconnect devices are known in the art wherein fused output power may be selectively switched from a power supply. Existing fusible disconnect switch devices, however, have not completely met the needs of those in the art and improvements are desired.

<CIT> discloses a high current fusible disconnect switch device including a switch housing configured to receive a pluggable touch-safe fuse module, and a dual slide bar actuator assembly for opening and closing switch contacts. The dual slide bar elements are each coupled to bias elements that store and release energy to affect switch opening and closing operations. The switch opening and closing operation is multi-staged wherein only the first slider element is movable in the first stage, and both the first and second slider elements are movable in the second stage.

Non-limiting and non-exhaustive embodiments are described with reference to the following Figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

Fusible circuit protection devices are sometimes utilized in an array on electrical panels and the like in an electrical power distribution system. Each fusible circuit protection device includes a single fuse or multiple fuses depending on the application, and each fusible circuit protection device protects load side circuitry from overcurrent conditions and the like that may potentially damage load side systems and components.

One type of fusible circuit protection device is a fusible switch disconnect device. In such fusible switch disconnect devices, switch contacts are provided to make or break electrical connection to and through their respective fuses. Fusible switch disconnect devices can be advantageous from a number of perspectives, but are nonetheless disadvantaged in certain applications.

For example, while conventional fusible switch disconnect devices are satisfactory for breaking alternating current (AC) circuitry by operation of a switch contact, the switching of high energy DC circuitry can be problematic. When switched under load, electrical arcing is typically generated at the switch contacts. Unlike AC current, where such arcing has an opportunity to extinguish at any voltage zero crossing of the alternating voltage wave, the DC current and voltage potential remain at a constant level during the breaking of switch contacts making it very difficult for the arc to extinguish. This constant DC voltage potential further tends to create sustained arcing conditions that will erode the switch contacts very quickly. Sustained high temperatures associated with DC arcing conditions can contribute to further switch mechanism degradation, and perhaps may even lead to catastrophic failure of the fusible switching disconnect device if not carefully controlled. Of course, as the voltage of the DC circuitry increases, electrical arcing issues become more severe.

To safely contain arc energy inside the housings of the fusible switch disconnect device, known fusible switch disconnect devices are relatively large devices. Larger fusible switch disconnect devices tend to be more expensive than smaller ones, and following general trends to reduce component size in the electrical industry smaller fusible disconnect switch devices are desired in the marketplace. Balancing the need to contain arc energy with a desire for smaller fusible switch disconnect devices, however, presents practical challenges. Improvements to fusible switch disconnect devices are accordingly desired that facilitate a more compact and lower cost solution to protect DC circuitry than has heretofore been provided.

<FIG> illustrates an array <NUM> of fusible circuit protection devices <NUM> that may pose electrical arcing issues and that may benefit from the improvements described below when utilized to protect high energy, DC circuitry. In the illustrated example, the fusible circuit protection devices <NUM> are arranged in a plurality of rows <NUM> wherein the devices <NUM> are arranged side-by-side with eight such devices <NUM> in each row. In the example shown, three rows <NUM> are depicted for a total of twenty-four devices <NUM> in the array <NUM>. However, even greater numbers of rows may be provided depending on the power system being protected. Also, it is understood that the devices <NUM> may be arranged in columns instead or rows, or in columns and rows as desired.

The rows <NUM> of devices <NUM> may further be provided in an enclosure <NUM> including a base wall <NUM>, lateral side walls <NUM> and <NUM> depending from the base wall <NUM>, end walls <NUM> and <NUM> depending from the base wall <NUM> and interconnecting the side walls <NUM> and <NUM>, and an optional lid. The rows <NUM> of devices <NUM> may be mounted to a DIN Rail (not shown in <FIG>) extending on the base wall <NUM>. The enclosure <NUM> is sometimes referred to as a combiner box wherein a relatively large number of electrical connections, both line side and load side in the power system, are established. The combiner box may be mounted vertically or horizontally at any location necessary or desired. In other applications, the enclosure <NUM> may be referred to as an electrical panel, control panel, or panelboard that also accommodates other electrical components besides the fusible circuit protection devices <NUM>.

In normal operation, current flows from the line side of an electrical power system through each device <NUM> and the fuse therein to the load side protected circuitry. Using the switches provided in the devices <NUM>, the load side circuitry associated with the devices <NUM> may be electrically isolated from the line side, independent of any operation of the fuse itself. As such, the devices <NUM> may desirably be switched on and off without having to remove the fuses. The switches of such devices may be opened manually or automatically in response to detected circuit conditions, even in anticipation of an opening of the fuse.

The possible opening and closing of the switches, whether manually or automatically, in a relatively large number of devices <NUM> in close proximity to one another requires effective arc energy containment when the circuitry protected is high energy, high voltage DC circuitry. As such, and as mentioned above, the devices <NUM> as conventionally implemented tend to increase in size as the voltage and current increases for the electrical power system to be protected. Considering the number of such devices <NUM> in the array <NUM>, however, any reduction in size of the devices <NUM> on the component level may result in significant reduction of size of the array <NUM> on a systems level.

<FIG> is a side elevational view of a portion of an exemplary embodiment of a fusible switching disconnect device <NUM> that may be utilized as the device <NUM> in the array <NUM> shown in <FIG> and that has already succeeded in reducing the size of an array <NUM> in certain power systems as well as provides other benefits. The disconnect device <NUM> generally includes a disconnect housing <NUM> and a finger-safe rectangular fuse module <NUM> having terminal blades received in pass through openings in the top of the disconnect device <NUM> such that the fuse module <NUM> can be plugged-in to the disconnect housing <NUM> or removed from the disconnect housing <NUM> by hand by grasping the exposed housing of the rectangular fuse module <NUM> and either pushing it toward the disconnect housing <NUM> to engage the terminal blades or pulling it away from the disconnect housing <NUM> to disengage the terminal blades from connecting terminals in the disconnect housing <NUM>. Such an arrangement has been well received and one of its benefits is that it does not require conventional tools to engage or disengage conventional fasteners to remove or install the fuse module <NUM>.

The device <NUM> includes a disconnect housing <NUM> fabricated from an electrically nonconductive or insulative material such as plastic, and the disconnect housing <NUM> is configured or adapted to receive a retractable rectangular fuse module <NUM>. The disconnect housing <NUM> and its internal components described below, are sometimes referred to as a base assembly that receives the retractable fuse module <NUM>. The internal components of the disconnect housing <NUM> include switching elements and actuator components described further below, although it should be understood that the disconnect housing <NUM> and its internal components represent only one example of a possible disconnect device that may benefit from the inventive features described further below.

The fuse module <NUM> in the exemplary embodiment shown includes a rectangular housing <NUM> fabricated from an electrically nonconductive or insulative material such as plastic, and conductive terminal elements in the form of terminal blades <NUM> extending from the housing <NUM>. In the example shown, the terminal blades <NUM> extend in spaced apart but generally parallel planes extending perpendicular to the plane of the page of <FIG>. A primary fuse element or fuse assembly is located within the housing <NUM> and is electrically connected between the terminal blades <NUM> to provide a current path therebetween. Such fuse modules <NUM> are known and in one embodiment the rectangular fuse module <NUM> is a CUBEFuse™ power fuse module commercially available from Cooper Bussmann of St. Louis, Missouri. The fuse module <NUM> provides 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 blades <NUM> in response to predetermined current conditions flowing through the fuse element in use. When the fuse element opens in such a manner, the fuse module <NUM> must 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 module <NUM> with considerable performance variations in use. Also, the fuse module <NUM> may 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 module <NUM> can be quickly identified for replacement via a visual change in appearance when viewed from the exterior of the fuse module housing <NUM>. Such fuse state indication features may involve secondary fuse links or elements electrically connected in parallel with the primary fuse element in the fuse module <NUM>.

A conductive line side fuse clip <NUM> may be situated within the disconnect housing <NUM> and may receive one of the terminal blades <NUM> of the fuse module <NUM>. A conductive load side fuse clip <NUM> may also be situated within the disconnect housing <NUM> and may receive the other of the fuse terminal blades <NUM>. The line and load side fuse clips <NUM>, <NUM> may be biased with spring elements and the like to provide some resistance to the plug-in installation and removal of the respective terminal blades <NUM>, and also to ensure sufficient contact force to ensure electrical connection therebetween when the terminal blades <NUM> and the fuse clips <NUM>, <NUM> are engaged.

The line side fuse clip <NUM> may be electrically connected to a first line side terminal <NUM> provided in the disconnect housing <NUM>, and the first line side terminal <NUM> may include a stationary switch contact <NUM>. The load side fuse clip <NUM> may be electrically connected to a load side connection terminal <NUM>. In the example shown, the load side connection terminal <NUM> is a box lug terminal operable with a screw <NUM> to 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 actuator <NUM> is further provided in the disconnect housing <NUM>, and is mechanically coupled to an actuator link <NUM> that, in turn, is coupled to a sliding actuator bar <NUM>. The actuator bar <NUM> carries a pair of switch contacts <NUM> and <NUM>. In an exemplary embodiment, the switch actuator <NUM>, the link <NUM> and the actuator bar <NUM> may be fabricated from nonconductive materials such as plastic. A second conductive line side terminal <NUM> including a stationary contact <NUM> is also provided, and a line side connecting terminal <NUM> is also provided in the disconnect housing <NUM>. In the example shown, the line side connection terminal <NUM> is a box lug terminal operable with a screw <NUM> to 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 terminal <NUM> and the load side connecting terminal <NUM> are 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 housing <NUM> if desired.

Electrical connection of the device <NUM> to power supply circuitry, sometimes referred to as the line side, may be accomplished in a known manner using the line side connecting terminal <NUM>. Likewise, electrical connection to load side circuitry may be accomplished in a known manner using the load side connecting terminal <NUM>. 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 terminals <NUM> and <NUM> accordingly are exemplary only.

In the position shown in <FIG>, the disconnect device <NUM> is shown in the closed position with the switch contacts <NUM> and <NUM> mechanically and electrically engaged to the stationary contacts <NUM> and <NUM>, respectively. As such, when the device <NUM> is connected to line side circuitry with a first connecting wire via the line side connecting terminal <NUM>, and also when the load side terminal <NUM> is connected to load side circuitry with a connecting wire via the connecting terminal <NUM>, a circuit path is completed through conductive elements in the disconnect housing <NUM> and the fuse module <NUM> when the fuse module <NUM> is installed and when the primary fuse element therein is in a non-opened, current carrying state.

Specifically, electrical current flow through the device <NUM> is as follows when the switch contacts <NUM> and <NUM> are closed, when the device <NUM> is connected to line and load side circuitry, and when the fuse module <NUM> is installed. Electrical current flows from the line side circuitry through the line side connecting wire to and through the line side connecting terminal <NUM>. From the line side connecting terminal <NUM> current then flows to and through the second line terminal <NUM> and to the stationary contact <NUM>. From the stationary contact <NUM> current flows to and through the switch contact <NUM>, and from the switch contact <NUM> current flows to and through the switch contact <NUM>. From the switch contact <NUM> current flows to and through the stationary contact <NUM>, and from the stationary contact <NUM> current flows to and through the first line side terminal <NUM>. From the first line side terminal <NUM> current flows to and through the line side fuse clip <NUM>, and from the line side fuse clip <NUM> current flows to and through the first mating fuse terminal blade <NUM> on the line side. From the first terminal blade <NUM> current flows to and through the primary fuse element in the fuse module <NUM>, and from the primary fuse element to and through the second fuse terminal blade <NUM>. From the second terminal blade <NUM> current flows to and through the load side fuse clip <NUM>, and from the load side fuse clip <NUM> to and through the load side connecting terminal <NUM>. Finally, from the connecting terminal <NUM> current flows to the load side circuitry via the wire connected to the terminal <NUM>. As such, a circuit path or current path is established through the device <NUM> that includes the fuse element of the fuse module <NUM>.

In the example shown, disconnect switching to temporarily open the current path in the device <NUM> may be accomplished in multiple ways. First, and as shown in <FIG>, a portion of the switch actuator <NUM> projects through an upper surface of the disconnect housing <NUM> and is therefore accessible to be grasped for manual manipulation by a person. Specifically, the switch actuator <NUM> may be rotated from a closed position as shown in <FIG> to an open position in the direction of arrow A, causing the actuator link <NUM> to move the sliding bar <NUM> linearly in the direction of arrow B and moving the switch contacts <NUM> and <NUM> away from the stationary contacts <NUM> and <NUM>. Eventually, the switch contacts <NUM> and <NUM> become mechanically and electrically disengaged from the stationary contacts <NUM> and <NUM> and the circuit path between the first and second line terminals <NUM> and <NUM>, which includes the primary fusible element of the fuse module <NUM>, may be opened when the fuse terminal blades <NUM> are received in the line and load side fuse clips <NUM> and <NUM>.

When the circuit path in the device <NUM> is opened in such a manner via rotational displacement of the switch actuator <NUM>, the fuse module <NUM> becomes electrically disconnected from the first line side terminal <NUM> and the associated line side connecting terminal <NUM>. In other words, an open circuit is established between the line side connecting terminal <NUM> and the first terminal blade <NUM> of the fuse module <NUM> that is received in the line side fuse clip <NUM>. The operation of switch actuator <NUM> and the displacement of the sliding bar <NUM> to separate the contacts <NUM> and <NUM> from the stationary contacts <NUM> and <NUM> may be assisted with bias elements such as springs. Particularly, the sliding bar <NUM> may be biased toward the open position wherein the switch contacts <NUM> and <NUM> are separated from the contacts <NUM> and <NUM> by a predetermined distance. The dual switch contacts <NUM> and <NUM> mitigate, in part, electrical arcing concerns as the switch contacts <NUM> and <NUM> are engaged and disengaged by dividing the arcing potential to two different locations.

Once the switch actuator <NUM> of the disconnect device <NUM> is switched open to interrupt the current path in the device <NUM> and disconnect the fuse module <NUM>, the current path in the device <NUM> may be closed to once again complete the circuit path through the fuse module <NUM> by rotating the switch actuator <NUM> in the opposite direction indicated by arrow C in <FIG>. As the switch actuator <NUM> rotates in the direction of arrow C, the actuator link <NUM> causes the sliding bar <NUM> to move linearly in the direction of arrow D and bring the switch contacts <NUM> and <NUM> toward the stationary contacts <NUM> and <NUM> to close the circuit path through the first and second line terminals <NUM> and <NUM>. As such, by moving the actuator <NUM> to a desired position, the fuse module <NUM> and associated load side circuitry may be connected and disconnected from the line side circuitry while the line side circuitry remains "live" in an energized, full power condition. Alternatively stated, by rotating the switch actuator <NUM> to separate or join the switch contacts, the load side circuitry may be electrically isolated from the line side circuitry, or electrically connected to the line side circuitry on demand. While the switch actuator <NUM> and associated switching components is desirable in many applications, it is contemplated that the switch actuator <NUM> and related switching components may in some embodiments be considered optional and may be omitted.

Additionally, the fuse module <NUM> may be simply plugged into the fuse clips <NUM>, <NUM> or extracted therefrom to install or remove the fuse module <NUM> from the disconnect housing <NUM>. The fuse housing <NUM> projects from the disconnect housing <NUM> and is open and accessible from an exterior of the disconnect housing <NUM> so that a person simply can grasp the fuse housing <NUM> by hand and pull or lift the fuse module <NUM> in the direction of arrow B to disengage the fuse terminal blades <NUM> from the line and load side fuse clips <NUM> and <NUM> until the fuse module <NUM> is completely released from the disconnect housing <NUM>. An open circuit is established between the line and load side fuse clips <NUM> and <NUM> when the terminal blades <NUM> of the fuse module <NUM> are removed as the fuse module <NUM> is released, and the circuit path between the fuse clips <NUM> and <NUM> is completed when the fuse terminal blades <NUM> are engaged in the fuse clips <NUM> and <NUM> when the fuse module <NUM> is installed. Thus, via insertion and removal of the fuse module <NUM>, the circuit path through the device <NUM> can be opened or closed apart from the position of the switch contacts as described above.

Of course, the primary fuse element in the fuse module <NUM> provides still another mode of opening the current path through the device <NUM> when 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 module <NUM> opens, it does so permanently and the only way to restore the complete current path through the device <NUM> is to replace the fuse module <NUM> with another one having a non-opened fuse element. As such, and for discussion purposes, the opening of the fuse element in the fuse module <NUM> is permanent in the sense that the fuse module <NUM> cannot be reset to once again complete the current path through the device. Mere removal of the fuse module <NUM>, and also displacement of the switch actuator <NUM> as 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 module <NUM> and/or closing the switch contacts.

The fuse module <NUM>, or a replacement fuse module, can be conveniently and safely grasped by hand via the fuse module housing <NUM> and moved toward the switch housing <NUM> to engage the fuse terminal blades <NUM> to the line and load side fuse clips <NUM> and <NUM>. The fuse terminal blades <NUM> are extendable through openings in the disconnect housing <NUM> to connect the fuse terminal blades <NUM> to the fuse clips <NUM> and <NUM>. To remove the fuse module <NUM>, the fuse module housing <NUM> can be grasped by hand and pulled from the disconnect housing <NUM> until the fuse module <NUM> is completely released. As such, the fuse module <NUM> having the terminal blades <NUM> may be rather simply and easily plugged into the disconnect housing <NUM> and the fuse clips <NUM>, <NUM>, or unplugged as desired.

Such plug-in connection and removal of the fuse module <NUM> advantageously facilitates quick and convenient installation and removal of the fuse module <NUM> without requiring separately supplied fuse carrier elements common to some conventional fusible disconnect devices. Further, plug-in connection and removal of the fuse module <NUM> does not require conventional tools (e.g., screwdrivers and wrenches) and associated fasteners (e.g., screws, nuts and bolts) common to other known fusible disconnect devices. Also, the fuse terminal blades <NUM> extend through and outwardly project from a common side of the fuse module body <NUM>, and in the example shown the terminal blades <NUM> each extend outwardly from a lower side of the fuse housing <NUM> that faces the disconnect housing <NUM> as the fuse module <NUM> is mated to the disconnect housing <NUM>.

In the exemplary embodiment shown, the fuse terminal blades <NUM> extending from the fuse module body <NUM> are generally aligned with one another and extend in respective spaced-apart parallel planes. It is recognized, however, that the terminal blades <NUM> of the module <NUM> in 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 blades <NUM>, and the receiving fuse clips <NUM> and <NUM> in the disconnect housing <NUM> may serve as fuse rejection features that only allow compatible fuses to be used with the disconnect housing <NUM>. In any event, because the terminal blades <NUM> project away from the lower side of the fuse housing <NUM>, a person's hand when handling the fuse module housing <NUM> for plug in installation (or removal) is physically isolated from the terminal blades <NUM> and the conductive line and load side fuse clips <NUM> and <NUM> that receive the terminal blades <NUM> as mechanical and electrical connections therebetween are made and broken. The fuse module <NUM> is therefore touch safe (i.e., may be safely handled by hand to install and remove the fuse module <NUM> without risk of electrical shock).

The disconnect device <NUM> is rather compact and occupies a reduced amount of space in an electrical power distribution system including the line side circuitry and the load side circuitry than other known fusible disconnect devices and arrangements providing similar effect. In the device illustrated in <FIG> the disconnect housing <NUM> is provided with a DIN rail slot <NUM> that may be used to securely mount the disconnect housing <NUM> in 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 device <NUM>, a greater number of devices <NUM> may be mounted to the DIN rail in comparison to conventional fusible disconnect devices.

In another implementation the device <NUM> may be configured for panel mounting by replacing the line side terminal <NUM>, for example, with a panel mounting clip. When so provided, the device <NUM> can 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 of the exemplary device <NUM> as shown, the circuit path or current path through the device <NUM> is preferably connected and disconnected at the switch contacts <NUM>, <NUM>, <NUM>, <NUM> rather than at the fuse clips <NUM> and <NUM>. By doing so, electrical arcing that may occur when connecting/disconnecting the circuit path may be contained at a location away from the fuse clips <NUM> and <NUM> to provide additional safety for persons installing, removing, or replacing fuses. By opening the switch contacts with the switch actuator <NUM> before installing or removing the fuse module <NUM>, any risk posed by electrical arcing or energized conductors at the fuse and disconnect housing interface is eliminated. The disconnect device <NUM> is accordingly believed to be safer to use than many known fused disconnect switches.

The disconnect switching device <NUM> includes still further features, however, that improve the safety of the device <NUM> in the event that a person attempts to remove the fuse module <NUM> without first operating the actuator <NUM> to disconnect the circuit through the fuse module <NUM>, and also to ensure that the fuse module <NUM> is compatible with the remainder of the device <NUM>. That is, features are provided to ensure that the rating of the fuse module <NUM> is compatible with the rating of the conductive components in the disconnect housing <NUM>.

As shown in <FIG>, the disconnect housing <NUM> in one example includes an open ended receptacle or cavity <NUM> on an upper edge thereof that accepts a portion of the fuse housing <NUM> when the fuse module <NUM> is installed with the fuse terminal blades <NUM> engaged to the fuse clips <NUM>, <NUM>. The receptacle <NUM> is shallow such that a relatively small portion of the fuse housing <NUM> is received when the terminal blades <NUM> are plugged into the disconnect housing <NUM>. A remainder of the fuse housing <NUM>, however, generally projects outwardly from the disconnect housing <NUM> allowing the fuse module housing <NUM> to be easily accessed and grasped with a user's hand and facilitating a finger safe handling of the fuse module <NUM> for installation and removal without requiring conventional tools. It is understood, however, that the fuse housing <NUM> need not project as greatly from the switch housing receptacle when installed as depicted, and indeed could even be substantially entirely contained within the switch housing <NUM> if desired.

In the example shown in <FIG>, the fuse housing <NUM> includes a recessed guide rim <NUM> having a slightly smaller outer perimeter than a remainder of the fuse housing <NUM>, and the guide rim <NUM> is seated in the switch housing receptacle <NUM> when the fuse module <NUM> is installed. It is understood, however, that the guide rim <NUM> may be considered entirely optional in another embodiment and need not be provided. The guide rim <NUM> may in whole or in part serve as a fuse rejection feature that would prevent someone from installing a fuse module <NUM> having a rating that is incompatible with the conductive components in the disconnect housing <NUM>. Fuse rejection features could further be provided by modifying the terminal blades <NUM> in shape, orientation, or relative position to ensure that a fuse module having an incompatible rating cannot be installed.

In contemplated devices the base of the device <NUM> (i.e., the disconnect housing <NUM> and the conductive components therein) has a rating that is ½ of the rating of the fuse module <NUM>. Thus, for example, a base having a current rating of 20A may preferably be used with a fuse module <NUM> having a rating of 40A. Ideally, however, fuse rejection features such as those described above would prevent a fuse module of a higher rating, such as 60A, from being installed in the base. The fuse rejection features in the disconnect housing <NUM> and/or the fuse module <NUM> can be strategically coordinated to allow a fuse of a lower rating (e.g., a fuse module having a current rating of 20A) to be installed, but to reject fuses having higher current ratings (e.g., 60A 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 A variety of fuse ratings and base ratings are possible, and the base rating and the fuse module rating may vary or may be the same.

As a further enhancement, the disconnect housing <NUM> includes an interlock element <NUM> that frustrates any effort to remove the fuse module <NUM> while the circuit path through the first and second line terminals <NUM> and <NUM> via the switch contacts <NUM>, <NUM>, <NUM>, <NUM> is closed. The exemplary interlock element <NUM> shown includes an interlock shaft <NUM> at a leading edge thereof, and in the locked position shown in <FIG> the interlock shaft <NUM> extends through a hole in the first fuse terminal blade <NUM> that is received in the line side fuse clip <NUM>. Thus, as long as the projecting interlock shaft <NUM> is extended through the opening in the terminal blade <NUM>, the fuse module <NUM> cannot be pulled from the fuse clip <NUM> if a person attempts to pull or lift the fuse module housing <NUM> in the direction of arrow B. As a result, and because of the interlock element <NUM>, the fuse terminal blades <NUM> cannot be removed from the fuse clips <NUM> and <NUM> while the switch contacts <NUM>, <NUM> are closed and potential electrical arcing at the interface of the fuse clips <NUM> and <NUM> and the fuse terminal blades <NUM> is avoided. Such an interlock element <NUM> is believed to be beneficial for the reasons stated but could be considered optional in certain embodiments and need not be utilized.

The interlock element <NUM> is coordinated with the switch actuator <NUM> so that the interlock element <NUM> is moved to an unlocked position wherein the first fuse terminal blade <NUM> is released for removal from the fuse clip <NUM> as the switch actuator <NUM> is manipulated to open the device <NUM>. More specifically, a pivotally mounted actuator arm <NUM> is provided in the disconnect housing <NUM> at a distance from the switch actuator <NUM>, and a first generally linear mechanical link <NUM> interconnects the switch actuator <NUM> with the arm <NUM>. The pivot points of the switch actuator <NUM> and the arm <NUM> are nearly aligned in the example shown in <FIG>, and as the switch actuator <NUM> is rotated in the direction of arrow A, the link <NUM> carried on the switch actuator <NUM> simultaneously rotates and causes the arm <NUM> to rotate similarly in the direction of arrow E. As such, the switch actuator <NUM> and the arm <NUM> are rotated in the same rotational direction at approximately the same rate.

A second generally linear mechanical link <NUM> is also provided that interconnects the pivot arm <NUM> and a portion of the interlock element <NUM>. As the arm <NUM> is rotated in the direction of arrow E, the link <NUM> is simultaneously displaced and pulls the interlock element <NUM> in the direction of arrow F, causing the projecting shaft <NUM> to become disengaged from the first terminal blade <NUM> and unlocking the interlock element <NUM>. When so unlocked, the fuse module <NUM> can then be freely removed from the fuse clips <NUM> and <NUM> by lifting on the fuse module housing <NUM> in the direction of arrow B. The fuse module <NUM>, or perhaps a replacement fuse module <NUM>, can accordingly be freely installed by plugging the terminal blades <NUM> into the respective fuse clips <NUM> and <NUM>.

As the switch actuator <NUM> is moved back in the direction of arrow C to close the disconnect device <NUM>, the first link <NUM> causes the pivot arm <NUM> to rotate in the direction of arrow G, causing the second link <NUM> to push the interlock element <NUM> in the direction of arrow H until the projecting shaft <NUM> of the interlock element <NUM> again passes through the opening of the first terminal blade <NUM> and assumes a locked position with the first terminal blade <NUM>. As such, and because of the arrangement of the arm <NUM> and the links <NUM> and <NUM>, the interlock element <NUM> is slidably movable within the disconnect housing <NUM> between locked and unlocked positions. This slidable movement of the interlock element <NUM> occurs in a substantially linear and axial direction within the disconnect housing <NUM> in the directions of arrow F and H in <FIG>.

In the example shown, the axial sliding movement of the interlock element <NUM> is generally perpendicular to the axial sliding movement of the actuator bar <NUM> that carries the switchable contacts <NUM> and <NUM>. In the plane of <FIG>, the movement of the interlock element <NUM> occurs along a substantially horizontal axis, while the movement of the sliding bar <NUM> occurs along a substantially vertical axis. The vertical and horizontal actuation of the sliding bar <NUM> and the interlock element <NUM>, respectively, contributes to the compact size of the resultant device <NUM>, although it is contemplated that other arrangements are possible and could be utilized to mechanically move and coordinate positions of the switch actuator <NUM>, the switch sliding bar <NUM> and the interlock element <NUM>. Also, the interlock element <NUM> may be biased to assist in moving the interlock element <NUM> to the locked or unlocked position as desired, as well as to resist movement of the switch actuator <NUM>, the sliding bar <NUM> and the interlock element <NUM> from one position to another. For example, by biasing the switch actuator <NUM> to the opened position to separate the switch contacts, either directly or indirectly via bias elements acting upon the sliding bar <NUM> or the interlock element <NUM>, inadvertent closure of the switch actuator <NUM> to 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 actuator <NUM> back to the closed position shown in <FIG> to reset the device <NUM> and again complete the circuit path. If sufficient bias force is present, it can be practically ensured that the switch actuator <NUM> will not be moved to close the switch via accidental or inadvertent touching of the switch actuator <NUM>.

The interlock element <NUM> may 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 in <FIG>. Rails and the like may be formed in the disconnect housing <NUM> to facilitate the sliding movement of the interlock element <NUM> between the locked and unlocked positions.

The pivot arm <NUM> is further coordinated with a tripping element <NUM> for automatic operation of the device <NUM> to open the switch contacts <NUM>, <NUM>. That is, the pivot arm <NUM>, in combination a tripping element actuator described below, and also in combination with the linkage <NUM>, <NUM>, and <NUM> define a tripping mechanism to force the switch contacts <NUM>, <NUM> to 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 actuator <NUM> described above. Further, the tripping mechanism is multifunctional as described below to not only open the switch contacts, but to also to displace the switch actuator <NUM> and the interlock element <NUM> to their opened and unlocked positions, respectively. The pivot arm <NUM> and associated linkage may be fabricated from relatively lightweight nonconductive materials such as plastic.

In the example shown in <FIG>, the tripping element actuator <NUM> is an electromagnetic coil such as a solenoid having a cylinder or pin <NUM>, 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 pin <NUM> to 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 pin <NUM> along the axis of the coil. The plunger cylinder or pin <NUM> may 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 in <FIG>, when the plunger cylinder or pin <NUM> is extended in the direction of arrow F, it mechanically contacts a portion of the pivot arm <NUM> and causes rotation thereof in the direction of arrow E. As the pivot arm <NUM> rotates, the link <NUM> is simultaneously moved and causes the switch actuator <NUM> to rotate in the direction of arrow A, which in turn pulls the link <NUM> and moves the sliding bar <NUM> to open the switch contacts <NUM>, <NUM>. Likewise, rotation of the pivot arm <NUM> in the direction of arrow E simultaneously causes the link <NUM> to move the interlock element <NUM> in the direction of arrow F to the unlocked position.

It is therefore seen that a single pivot arm <NUM> and the linkage <NUM> and <NUM> mechanically couples the switch actuator <NUM> and the interlock element <NUM> during normal operation of the device, and also mechanically couples the switch actuator <NUM> and the interlock element <NUM> to the tripping element <NUM> for automatic operation of the device. An end of the link <NUM> connecting the switch actuator <NUM> and the sliding bar <NUM> that carries the switch contacts <NUM>, <NUM> is coupled to the switch actuator <NUM> at approximately a common location as the end of the link <NUM>, thereby ensuring that when the tripping element <NUM> operates to pivot the arm <NUM>, the link <NUM> provides a dynamic force to the switch actuator <NUM> and the link <NUM> to ensure an efficient separation of the contacts <NUM> and <NUM> with a reduced amount of mechanical force than may otherwise be necessary. The tripping element actuator <NUM> engages the pivot arm <NUM> at a good distance from the pivot point of the arm <NUM> when 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 actuator <NUM> back to the closed position that closes the switch contacts.

Suitable solenoids are commercially available for use as the tripping actuator element <NUM>. Exemplary solenoids include LEDEX® Box Frame Solenoid Size B17M of Johnson Electric Group (www. com) and ZHO-<NUM>/S Open Frame Solenoids of Zohnen Electric Appliances (www. In different embodiments, the solenoid <NUM> may be configured to push the arm <NUM> and cause it to rotate, or to pull the contact arm <NUM> and 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 arm <NUM> as described above, or with a pulling action on the pivot arm <NUM>. Likewise, the solenoid could operate on elements other than the pivot arm <NUM> if desired, and more than one solenoid could be provided to achieve different effects.

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 element <NUM> and the sliding bar <NUM> carrying the switch contacts <NUM>, <NUM> may be considered optional and these components could accordingly be independently actuated and separately operable if desired. Different types of actuator could be provided for different elements.

Moreover, in the example shown the trip mechanism is entirely contained within the disconnect housing <NUM> while still providing a relatively small package size. It is recognized, however, that the tripping mechanism may in whole or in part reside outside the disconnect housing <NUM>, such as in separately provided modules that may be joined to the disconnect housing <NUM>. 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 housing <NUM>. Specifically, the trip element actuator and linkage in a separately provided module may be mechanically linked to the switch actuator <NUM>, the pivot arm <NUM> and/or the sliding bar <NUM> of the disconnect housing <NUM> to provide comparable functionality to that described above, albeit at greater cost and with a larger overall package size.

The tripping element <NUM> and associated mechanism may further be coordinated with a detection element and control circuitry to automatically move the switch contacts <NUM>, <NUM> to the opened position when predetermined electrical conditions occur. In one exemplary embodiment, the second line terminal <NUM> is provided with an in-line detection element <NUM> that is monitored by control circuitry <NUM>. As such, actual electrical conditions can be detected and monitored in real time and the tripping element <NUM> can be intelligently operated to open the circuit path in a proactive manner independent of operation of the fuse module <NUM> itself and/or any manual displacement of the switch actuator <NUM>. That is, by sensing, detecting and monitoring electrical conditions in the line terminal <NUM> with the detection element <NUM>, the switch contacts <NUM>, <NUM> can be automatically opened with the tripping element <NUM> in response to predetermined electrical conditions that are potentially problematic for either of the fuse module <NUM> or the base assembly (i.e., the disconnect housing <NUM> and its components).

In particular, the control circuitry <NUM> may open the switch contacts in response to conditions that may otherwise, if allowed to continue, cause the primary fuse element in the fuse module <NUM> to permanently open and interrupt the electrical circuit path between the fuse terminals <NUM>. Such monitoring and control may effectively prevent the fuse module <NUM> from 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 device <NUM> becomes, 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 module <NUM> has to be replaced. It is recognized, however, that if certain circuit conditions were to occur, permanent opening of the fuse <NUM> may be unavoidable.

While the device <NUM> has delivered enhanced fusible switch disconnect features in a reduced package size, it remains limited in some aspects and for certain power systems. As previously mentioned, higher voltage, higher current power systems provide dramatically increased arc energy potential that must be safely contained in the device <NUM>. A potential solution to accommodating the arc energy of higher current, higher voltage DC power systems would be to increase the size and strength of the component parts of the disconnect device. While this could be accomplished, and in the past has been the approach adopted in the field, it undesirably increases the size and cost of the fusible disconnect device. Maintaining the physical package size of existing devices while offering improved capability to function in higher power electrical systems and/or reducing the size of existing devices with the same or enhanced improved capability to function in higher power electrical systems while also providing cost reduction remains somewhat of an elusive goal to manufacturers of fusible switch disconnect devices.

Considering the needs of high energy DC power systems, opportunities to improve devices such as the device <NUM> in a similar or reduced package size reside primarily in limiting arc severity and arc duration to a more manageable amount inside the device. In this regard, a limitation of known fusible switch disconnect devices has been found to reside in the switch mechanisms utilized. Slower acting switches provide more time for arcing to occur (i.e., increase a length of arcing duration as the switch is opened and closed), and switch contacts moving a smaller distance tend to break arcs less effectively than switch contacts that move a larger distance.

Improvements which may be incorporated in the devices <NUM> and the array <NUM> as described above to offer enhanced DC power system performance relative to the device <NUM> described above, will now be explained in relation to <FIG>. Like elements of the device <NUM> and like elements of the following embodiments are therefore indicated with like reference characters. It is to be understood, however, that the inventive embodiments and switch mechanisms described below do not necessarily require all of the particulars of the device <NUM> described and/or do not require the particulars of the fuse <NUM> for implementation. That is, some of the features described above in relation to the device <NUM> may be considered optional and may be omitted, while still achieving at least some of the benefits of the present invention. The device <NUM> and fuse <NUM> are therefore non-limiting comparative examples of the type of fusible switching disconnect device and fuse that would benefit from the improvements described below. Other types of fusible switching disconnect devices for fuses other than fuses having plug-in terminal blades, including but not limited to so-called cylindrical or cartridge fuses, may also benefit from the concepts disclosed herein and accordingly the embodiments described herein are offered for the sake of illustration rather than limitation. Method aspects will be in part apparent and in part explicitly discussed from the following description.

<FIG> illustrates a fusible switch disconnect device <NUM> that may be used as the device <NUM> in the array <NUM> shown in <FIG> with further benefits. The switch disconnect device <NUM> includes a switch disconnect housing <NUM> and terminal structure (not shown) similar to that described in relation to the fusible switch disconnect device <NUM> that receives a fuse such as the fuse <NUM> and establishes an electrical connection through the fuse <NUM>.

Like the fusible switch disconnect device <NUM>, the fusible switch disconnect <NUM> includes a rotary switch actuator <NUM> projecting upwardly and outwardly from a portion of the switch disconnect housing <NUM>. Linkage <NUM> such as the exemplary linkages described below in relation to <FIG> is provided to mechanically connect the rotary switch actuator <NUM> and a slider bar <NUM> that is movable along a linear axis in the switch disconnect housing <NUM>. The slider bar <NUM> includes a transverse switch contact bar element <NUM> that carries movable switch contacts <NUM>, <NUM> in the housing <NUM>. The linkage <NUM>, driven by the actuator <NUM>, selectively positions the movable contacts <NUM>, <NUM> along the linear axis toward and away from stationary contacts <NUM>, <NUM> that are fixed in position within the switch housing <NUM>.

The switch housing <NUM> is formed in the example shown with a top surface <NUM> from which the switch actuator <NUM> projects, and a bottom surface <NUM> opposing the top surface <NUM>. The stationary contacts <NUM>, <NUM> are seen to be positioned adjacent the bottom surface <NUM>, allowing the slider bar <NUM> and contact element <NUM> to move a greater distance than in an embodiment like the device <NUM> shown in <FIG> wherein the stationary contacts <NUM>, <NUM> are located at a distance from bottom of the housing <NUM>. As such, even if the housing <NUM> has a comparable size to the housing <NUM> of the device <NUM> in the vertical direction of the figures as illustrated, the device <NUM> can more effectively handle increased arc energy presented by a DC electrical power system. Comparatively, the movable switch contacts <NUM>, <NUM> traverse a longer path along the linear axis in the direction of arrow B or D between a fully opened positon (shown in solid lines in <FIG>) and a fully closed position (shown in phantom in <FIG>) wherein mechanical and electrical contact between the switch contacts <NUM>, <NUM> and <NUM>, <NUM> is made and broken. The larger path of travel, in turn, produces a larger gap between the contacts when fully opened. The gap length when the contacts are fully opened may be selected to be sufficiently large to overcome any tendency of an electrical arc to sustain itself across the gap as the switch contacts <NUM>, <NUM> are opened.

As shown in example of <FIG>, the housing bottom surface <NUM> further includes a pocket or recess <NUM> extending from the bottom surface <NUM>. The pocket or recess <NUM> receives and accommodates a portion of the slider bar <NUM> when the switch contacts are fully closed and facilitates the increased path length of travel for the switch contacts <NUM>, <NUM> when the switch contacts are closed. The pocket or recess <NUM> further includes a bias element seat <NUM> (<FIG>) for a bias element such as a compression spring that assists with opening of the switch contacts. The pocket or recess <NUM> projects from the bottom surface <NUM> as shown, and hence enlarges the outer dimension of the device <NUM> somewhat, but advantageously maximizes the contact gap separation on the inside of the housing <NUM> when the switch is opened.

<FIG> schematically illustrates a DC electrical power system <NUM> for supplying electrical power from a power supply or line-side circuitry <NUM> to power receiving or load-side circuitry <NUM>. In contemplated embodiments the line-side circuitry <NUM> and load-side circuitry <NUM> may be associated with a panelboard <NUM> that includes a fusible switching disconnect device <NUM> either singly or in an array such as the array <NUM> illustrated in <FIG>. While one fusible switching disconnect device <NUM> is shown, it is contemplated that in a typical installation a plurality of fusible switching disconnect devices <NUM> would be provided in the panel board <NUM> that each respectively receives input power from the line-side circuitry <NUM> via, for example, a bus bar (not shown), and outputs electrical power to one or more of various different electrical loads <NUM> associated with branch circuits of the larger electrical power system <NUM>. As such, an array of devices <NUM> may be provided on the panelboard <NUM>.

The fusible switching disconnect device <NUM> may be configured as a compact fusible switching disconnect device such as those described above and further below that advantageously combine switching capability and enhanced fusible circuit protection in a single, compact switch housing <NUM>. As shown in <FIG>, the fusible switching disconnect device <NUM> defines a circuit path through the switch housing <NUM> between the line-side circuitry <NUM> and the load-side circuitry <NUM>.

As shown in <FIG>, the contact element <NUM> includes dual contact bars 210a and 210b that are spaced apart and oriented generally parallel to one another. Each contact bar 210a, 210b respectively includes switch contacts 212a, 212b and 214a, 214b on their respective opposing ends. The switch contacts 212a, 212b and 214a, 214b move with the contact element bars 210a, 210b and engage or disengage the stationary switch contacts 216a, 216b, 218a, 218b located adjacent the bottom of the switch housing <NUM> as shown in <FIG>. The stationary switch contacts 216a, 216b are located on one side of the pocket or recess <NUM> and the stationary contacts 218a, 218b are located on an opposing side of the pocket or recess <NUM> at the bottom of the housing <NUM>. As such, the contacts 216a, 216b provide a first set of switch contacts on the line-side, and the contacts 218a, 218b provide a second set of switch contacts on the load-side that, in turn, connects to the fuse <NUM>. The movable contacts 212a, 212b and 214a, 214b are engaged or disengaged to open and close the switch and complete or break the connection of the fuse <NUM> and the line-side circuitry.

Compared to the device <NUM> shown in <FIG> having two movable contacts, the dual pairs of switch contacts 212a, 212b and 214a, 214b on the contact element <NUM> and the dual pairs of switch contacts 216a, 216b and 218a, 218b in the switch housing <NUM>, the device <NUM> can provide much more effective breaking of electrical arcs than the device <NUM> as the contacts are opened and closed. Specifically, in the device <NUM> arc energy is broken at the respective locations of four pairs of contacts instead of two, and arc division occurs at those four locations instead of two, resulting in less severe arcing at each location. Relative to conventional fusible switching disconnect devices, the increased number of switch contacts decreases operating temperature of the switch contacts when switched under high current loads. Coupled with the larger contact gap separation as described above, the increased number of switch contacts in the device <NUM> may either dissipate arcing energy much more easily than the device <NUM> for comparable voltages and currents that are being switched, or accommodate higher current and higher voltage switching that are beyond the capabilities of the device <NUM>.

Returning now to <FIG>, the circuit path of the fusible switching disconnect device <NUM> includes, as shown in <FIG>, a line-side connecting terminal <NUM> and the movable switchable contacts 212a, 212b, 214a, 214b (carried on the contact bar element <NUM> and the dual bars 210a, 210b as shown in <FIG>) and stationary switch contacts 216a, 216b associated with the line-side terminal connecting terminal <NUM>, stationary contacts 218a, 218b associated with a first fuse contact terminal <NUM>, and a second fuse contact terminal <NUM>. The removable overcurrent protection fuse <NUM> is connected between the fuse contact terminals <NUM> and <NUM>, and a load-side connecting terminal <NUM> completes the current path. Each of the elements <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> that define a portion of the circuit path are included in the housing <NUM> while the overcurrent protection fuse <NUM> is separately provided but used in combination with the housing <NUM> and the conductive elements <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> in the switch housing <NUM>.

The switch contacts 212a, 212b, 214a, 214b are movable relative to the stationary switch contacts 216a, 216b, 218a, 218b between opened and closed positions to electrically connect or isolate the line-side connecting terminal <NUM> and the fuse contact terminal <NUM> and hence connect or disconnect the load-side circuitry <NUM> from the line-side circuitry <NUM> when desired. When the fusible switching disconnect device <NUM> is connected to energized line-side circuitry <NUM>, and also when the switch contacts 212a, 212b, 214a, 214b are closed as shown in phantom in <FIG> and the fuse <NUM> is intact, electrical current flows through the line-side connecting terminal <NUM> of the fusible switching disconnect device <NUM> and through the switchable contacts 212a, 212b, 214a, 214b and 216a, 216b, 218a, 218b, to and through the fuse contact terminal <NUM> and the fuse <NUM> to the fuse contact terminal <NUM>, and to and through the load-side connecting terminal <NUM> to the load. When the switch contacts 212a, 212b, 214a, 214b are opened, an open circuit is established between the contact 216a, 216b, 218a, 218b in the switch housing <NUM> of the fusible switching disconnect device <NUM> and the load-side circuitry <NUM> is electrically isolated or disconnected from the line-side circuitry <NUM> via the fusible switching disconnect device <NUM>. When the contacts 212a, 212b, 214a, 214b are again closed, electrical current flow resumes through the current path in the fusible switching disconnect device <NUM> and the load-side circuitry <NUM> is again connected to the line-side circuitry <NUM> through the fusible switching disconnect device <NUM>.

When the overcurrent protection fuse <NUM> is subjected to a predetermined electrical current condition when the switch contacts 212a, 212b, 214a, 214b and 216a, 216b, 218a, 218b are closed, however, the overcurrent protection fuse <NUM>, and specifically the fusible element (or fusible elements) therein is configured to permanently open or fail to conduct current any longer, creating an open circuit between the fuse contact terminals <NUM> and <NUM>. When the overcurrent protection fuse <NUM> opens in such a manner, current flow through the fusible switching disconnect device <NUM> is interrupted and possible damage to the line-side circuitry <NUM> is avoided. In one contemplated embodiment, the fuse <NUM> may be a rectangular fuse module such as a CUBEFuse™ power fuse module commercially available from Bussmann by Eaton of St. Louis, Missouri. In other embodiments, the overcurrent protection fuse <NUM> may be a cylindrical fuse such as a Class CC fuse, a so-called Midget fuse, or an IEC 10x38 fuse also available from Bussmann by Eaton.

Because the overcurrent protection fuse <NUM> permanently opens, the overcurrent protection fuse <NUM> must be replaced to once again complete the current path between the fuse contact terminals <NUM> and <NUM> in the fusible switching disconnect device <NUM> such the power can again be supplied to the load-side circuitry <NUM> via the fusible switching disconnect device <NUM>. In this aspect, the fusible switching disconnect device <NUM> is contrasted with a circuit breaker device that is known to provide overcurrent protection via a resettable breaker element. At least in part because the device <NUM> does not involve or include a resettable circuit breaker element in the circuit path completed in the switch housing <NUM>, the fusible switching disconnect device <NUM> is considerably smaller than an equivalently rated circuit breaker device providing similar overcurrent protection performance.

As compared to conventional arrangements wherein fusible devices are connected in series with separately packaged switching elements, the fusible switching disconnect device <NUM> is relatively compact and can provide substantial reduction in size and cost while providing comparable, if not superior, circuit protection performance.

When the compact fusible switching disconnect devices <NUM> are utilized in combination in a panelboard <NUM>, current interruption ratings of the panelboard <NUM> may be increased while the size of the panelboard <NUM> may be simultaneously reduced. The compact fusible disconnect device <NUM> may advantageously accommodate fuses <NUM> without involving a separately provided fuse holder or fuse carrier that is found in certain types of conventional fusible switch disconnect devices. The compact fusible disconnect device <NUM> may also be configured to establish electrical connection to the fuse contact terminals <NUM>, <NUM> without fastening of the fuse <NUM> to the line and load-side terminals with separate fasteners, and therefore provide still further benefits by eliminating certain components of conventional fusible disconnect constructions while simultaneously providing a lower cost, yet easier to use fusible circuit protection product <NUM>.

<FIG> illustrates a first improved switch mechanism <NUM> that may be included in the device <NUM>. <FIG> illustrate more detailed implementations of the switch mechanism <NUM>. The switch mechanism <NUM> includes the rotary switch actuator <NUM> having a round body <NUM> that is rotatably mounted in the switch housing <NUM> about a center pin or axle <NUM>. The actuator <NUM> is formed with a radially extending handle portion <NUM> that projects from the switch housing <NUM> when installed, and an elongate link guide member <NUM> also depends radially from the round body <NUM> at an oblique angle from the handle portion <NUM>. The elongate link guide member <NUM> includes an elongated and generally linearly extending slot <NUM> therein and extending radially from the round body <NUM> of the actuator <NUM>.

An actuator link or rod <NUM> is received in the slot <NUM> and also in a cam surface <NUM> (<FIG>) via a first end <NUM> that is bent at a right angle from the longitudinal axis of the link <NUM>. At a second end <NUM> of the link <NUM> opposing the first end <NUM>, the link <NUM> is rotatably mounted to the distal end of the sliding bar <NUM>. The link <NUM> is generally linear between the two ends <NUM>, <NUM> and has a length selected, as discussed below, to achieve a desired contact separation of the switch mechanism when opened.

The end <NUM> of the link <NUM> may rotate and translate relative to the guide member <NUM> as it traverses the slot <NUM> in use, while the end <NUM> of the link <NUM> is rotatable, but not translatable, relative to the slider bar <NUM>. In this context, translatable motion of the link end <NUM> refers to the ability of the link <NUM> to move closer to or farther away from the axis of rotation of the actuator body <NUM>. In contrast, the end <NUM> of the link <NUM> is pinned to the end of the sliding <NUM> bar and its position along the sliding linear axis is dictated by the sliding bar <NUM>. While the link end <NUM> can rotate or pivot relative to the slider bar <NUM>, it is incapable of translation movement relative to the slider bar <NUM>.

In <FIG> and <FIG>, the switch mechanism <NUM> is shown in the open position. The link <NUM> is accordingly shown in the open position as extending obliquely to the contact element <NUM> and also to the linear axis of motion of the slider bar <NUM>. By rotating the actuator body <NUM> in the direction of arrow C, the end <NUM> of the link <NUM> is constrained by the slot <NUM> and the cam surface <NUM> while the end <NUM> drives the slider bar <NUM> and its switch contacts <NUM>, <NUM> toward the switch contacts <NUM> and <NUM>. When fully closed as shown in <FIG>, the link <NUM> is oriented generally vertically and assumes a generally perpendicular orientation to the contact element <NUM> to provide maximum contact force. Alternatively stated, in the closed position the link <NUM> is generally aligned with the linear axis of the slider bar <NUM> and maximum contact force is therefore established. The switch actuator <NUM> can be rotated in the opposite direction to return the mechanism to the open position. The switch mechanism operates in reverse as it is opened and closed with the actuator <NUM>.

As shown in <FIG> counteracting bias elements such as a leaf spring <NUM> and a compression spring <NUM> act on opposing sides of the contact element <NUM>. The leaf spring <NUM> (shown separately in <FIG>) provides enhanced contact closing force, while the compression spring <NUM> provides for enhanced contact opening force. It is understood that in other embodiments, other biasing arrangements are possible, including but not limited to a tension spring in lieu of a compression spring in combination with bias elements other than a leaf spring.

<FIG> illustrates an exemplary cam profile for the cam surface <NUM>. The cam profile is seen to include a linearly extending portion <NUM> that extends generally vertically or parallel to the vertical axis of movement of the slider bar <NUM>. The linearly extending portion <NUM> opens to an arcuate portion <NUM> that completes a substantially <NUM>° arcuate path culminating in a generally horizontally extending portion <NUM>. With the illustrated cam profile, the slider bar <NUM> is accelerated toward to the stationary contacts as the actual link <NUM> traverses the cam surface <NUM> and reduces arcing time as the contact are closed. That is, the velocity of the slider bar <NUM> as the cam surface <NUM> is followed is non-uniform to achieve a quicker reduction of the contact gap in first phase of contact closing and slower movement of the slider bar <NUM> as the contact closing is near completion. Quicker opening or closing of the contacts either breaks or suppresses arcing of a given potential more easily, or provides capability of breaking and suppressing higher intensity arcs than a comparable device without such a cam profile.

<FIG> illustrates an alternative cam surface <NUM> for the device <NUM> and the switch mechanism <NUM>. The cam surface <NUM> has a profile that includes an elongated and linear extending oblique portion <NUM> that extends obliquely to the to the vertical axis of movement of the slider bar <NUM>, and an end section <NUM> that is arcuate. The end section <NUM> is designed to reach maximum downward displacement of the link <NUM> at its end <NUM> about <NUM>° before dead end and then lift the end <NUM> as it approaches the dead end of the cam surface <NUM>. Advantageously, this cam profile over-compresses the contacts as the mechanism is closed, and then retracts the contacts to produce the desired contact force. The end <NUM> of the cam profile provides a detent feature that reliably keeps the switch closed in a stable position counteracted by the features described above.

<FIG> is a perspective view of the leaf spring <NUM> described in one example. The leaf spring <NUM> includes forked ends <NUM>, <NUM> including prongs <NUM>, <NUM> separated by an opening <NUM>. The dual sets of prongs <NUM>, <NUM> facilitate the closing of the slider bar including the dual sets of switch contacts 212a, 212b, 214a, 214b described above. The material for the leaf <NUM> spring is selected to provide the closing contact force desired. The leaf spring <NUM> may be assembled with the actuator link <NUM> such that downward movement of the link <NUM> causes the leaf spring <NUM> to compress and release force as desired to obtain and maintain a desirable amount of contact closing force.

<FIG> illustrates another switch mechanism <NUM> that can be seen to closely correspond to the mechanism <NUM> described above, but omits the slot <NUM> in the guide element <NUM>. As a result, the end <NUM> of the link <NUM> can rotate relative to the guide element <NUM>, but it cannot translate relative to the guide element <NUM>. As such, in this arrangement the link <NUM> is not compatible with the cam surface of claim <NUM> and the housing <NUM> accordingly does not include a cam surface. The arrangement shown in <FIG> is sometimes referred to as a direct linear switch mechanism. Coupled with the dual contact bar element <NUM> and the dual sets of switch contacts, the direct linear mechanism can effectively make and break electrical connections without excessive arcing at comparatively lower cost than the linear cam switch arrangement described above. Opened and closed positions of the switch contacts are obtained by rotating the switch actuator in opposite directions to raise or lower the slider bar <NUM>.

<FIG> illustrates another switch mechanism <NUM> for the device <NUM> that is a rotary switch mechanism. In this switch mechanism, the link <NUM> is coupled to the guide element <NUM> at the end <NUM> and is coupled to an extension <NUM> of a rotary contact member <NUM> to which the contact element <NUM> is attached. Unlike the previously described embodiments, the movable contacts <NUM>, <NUM> are coupled to opposing sides of the contact element <NUM> and thus face in opposite directions. The rotary contact member <NUM> is rotatably mounted in the switch housing <NUM> at a distance from the switch actuator <NUM>, and by virtue of the link <NUM> when the switch actuator <NUM> is rotated in the direction of arrow C the rotary contact member <NUM> is likewise rotated in the same direction. Since the contact element <NUM> rotates with the rotary contact member <NUM> the switch contacts <NUM>, <NUM> (actually 212a, 212b and 214a, 214b by virtue of the dual bar contact element <NUM>) may be engaged and disengaged from the stationary switch contacts <NUM>, <NUM> (actually 216a, 216b, 218a, 218b) as shown in <FIG>. The rotary mechanism is shown in a closed position in <FIG> and in an open positon in <FIG>. The opened and closed positions are obtained by rotating the switch actuator <NUM> in different directions. For certain applications, the rotary switch mechanism may provide additional space savings and offer further reduction in the housing size than the previously described switch mechanisms.

<FIG> illustrates another switch mechanism <NUM> for the device <NUM> that is a rocker switch mechanism. In this arrangement, the guide member <NUM> of the switch actuator <NUM> is interfaced with a linear slot <NUM> of a rocker element <NUM>. The rocker element <NUM> is rotatably mounted in the housing <NUM> at a first end <NUM>, and attaches to the end <NUM> of the link <NUM> at its opposite end <NUM>. The guide member <NUM> may include a pin <NUM> that engages the slot <NUM> in the rocker element <NUM>. When the switch actuator <NUM> is rotated in the direction of arrow C. the pin <NUM> that is constrained to the slot <NUM> causes the rocker element <NUM> to pivot about the end <NUM> in the same direction as arrow C. As the rocker element <NUM> pivots, the link <NUM> drives the slider bar <NUM> downward to close the switch contacts. <FIG> shows a more detailed implementation of the mechanism <NUM> in an opened position. The closed and opened positons are obtained by rotating the switch actuator <NUM> in opposite directions. Neither <FIG> or <FIG> show a cam according to claim <NUM>.

The benefits and advantages of the inventive fusible switch disconnect devices described are now believed to have been amply illustrated in relation to the embodiments disclosed.

The overcurrent protection fuse may optionally be a rectangular fuse module having plug-in terminal blades.

Claim 1:
A fusible switch disconnect device (<NUM>) comprising:
a housing (<NUM>) including opposed top and bottom surfaces (<NUM>, <NUM>), the top surface configured to receive and accept an overcurrent protection fuse and the bottom surface formed with a pocket (<NUM>) extending from the bottom surface;
a current path defined in the switch housing and connecting to the overcurrent protection fuse when received, the current path including a first pair of stationary switch contacts (216a, 216b) and a second pair of stationary switch contacts (218a, 218b) proximate the bottom surface on respectively different sides of the pocket; and
a switch mechanism selectively positionable between a first position and a second position to connect and disconnect the current path without removing the overcurrent protection fuse, the switch mechanism comprising:
a rotary switch actuator (<NUM>) selectively positionable between first and second positions to cause the current path to open or close while the overcurrent protection fuse is connected; and
a contact element (<NUM>, <NUM>), responsive to the position of the rotary switch actuator, and carrying two pairs of movable switch contacts (212a, 212b, 214a, 214b) for selective engagement with the first and the second pairs of stationary switch contacts, wherein a portion of the contact element descends into the pocket when the current path is closed;
wherein the switch mechanism further comprises a link (<NUM>) having a first end (<NUM>) and a second end (<NUM>), the first end coupled to the rotary switch actuator and the second end coupled to the contact element (<NUM>, <NUM>);
wherein the rotary switch actuator defines an elongated guide member (<NUM>) receiving the first end of the link, and wherein the housing comprises a cam surface (<NUM>) cooperating with the first end of the link; and
wherein the cam surface includes a linearly extending portion (<NUM>) and one arcuate portion (<NUM>).