Extension member for rotary switch actuation

The disclosure describes a switch extension device and method of installing such a device on a unit of electrical equipment with a closable housing containing a switch and electrically charged components, such as a transformer with a rotary oil safety switch inside the transformer terminal cabinet. The device includes a switch coupling member for mechanically manipulating a switch between at least a first switch position and a second switch position. The switch is disposed inside the closed housing containing components that are electrically charged when the switch is in the first position and not electrically charged when the switch is in the second position. The device also has an extension member with an external portion that extends outside of the closed housing for access by the user without opening the closed housing. Physical manipulation of the external portion of the extension member is mechanically translated to the switch coupling member for mechanically manipulating the switch between at least the first switch position and the second switch position.

FIELD

The invention relates to the field of safety devices for electrical equipment and, more specifically, safely actuating switches adjacent electrically charged components of electrical equipment.

BACKGROUND

Distribution and storage of electricity are critical aspects of modern infrastructure. Power distribution includes the transmission of power at high voltage. Once power is generated it is conditioned and transformed for transmission to remote users of power. As these high current and voltage power sources reach their destinations, they must be adjusted to the needs of the loads that will use them, whether that be residential or commercial standards, or more esoteric industrial loads. Transformers are critical component in these systems for adjusting the voltage between generation, distribution, and use of electrical power. Like all electrical equipment, transformers and the systems of which they are a part require periodic service.

Many transformers include an oil switch that must be toggled or rotated to the off position before the transformer can safely be serviced. For example, any enclosed pad mount transformers with an oil switch in the terminal cabinet will require manipulation of the oil switch before service. Unfortunately, this oil switch is often disposed within the transformer housing, located within the transformer terminal cabinet. Because this internal area of the transformer also includes active high-voltage components, it is a significant risk to the technician servicing the transformer to open the housing and access the oil switch.

In order to service a transformer with an internal oil switch, the technician must first open an access panel, generally a hinged and lockable door, that provides access to the transformer terminal cabinet within the transformer housing. Among the active electrical components in the transformer terminal cabinet, is a rotary oil switch that is rotated to be able to safely power down the transformer for service. The rotary oil switch is then turned by hand or using an electrical service hot stick with a hooked end to engage a loop or other feature on the oil switch. Once the switch is fully in the off position, service on the transformer unit can proceed.

Accidental contact with the active electrical components within the transformer cabinet is extremely dangerous to the technician and can result in fatal injury. Danger may be particularly high in older equipment where safety features, such as insulation, of the exposed electrical components have degraded. While service technicians are highly trained in understanding these risks, routine exposure tends to reduce their safety mindedness. Once a hand is within the cabinet in the vicinity of the exposed electrical components, any number of circumstances can cause accidental contact with active electrical components and resulting injury or death.

While transformer cabinets could be designed with a safety switch in a separate access panel, that is not the standard configuration. Even if this change was made in the industry, there would still be the vast installed base of transformers that do not include such a feature and will need to be safely serviced for many years to come.

SUMMARY

Technical Problem

There is a need for a device and method of operating the safety switch adjacent electrically charged components of electrical equipment, that is simpler, more reliable, and safer for electrical service technicians.

Solution to Problem

The present invention is a switch extension to allow a technician to manipulate a safety switch from outside the housing of the electrical equipment that contains the active electrical components and is installed in the electrical equipment for use by service technicians. More specifically, one aspect of the invention is a device with a switch coupling member for mechanically manipulating a switch between at least a first switch position and a second switch position. The switch is disposed inside the closed housing containing components that are electrically charged when the switch is in the first position and not electrically charged when the switch is in the second position. The device also has an extension member with an external portion that extends outside of the closed housing for access by the user without opening the closed housing. Physical manipulation of the external portion of the extension member is mechanically translated to the switch coupling member for mechanically manipulating the switch between at least the first switch position and the second switch position.

The device may include a switch coupling member that accommodates a rotary switch and mechanically manipulating the switch comprises rotating the switch between the first switch position and the second switch position. For example, the switch coupling member may be a cylindrical cup where the internal diameter is greater than the diameter of the rotating portion of the rotary switch and the cylindrical cup includes a switch manipulation feature such that rotation of the cylindrical cup rotates the rotating portion of the rotary switch. A slot in the cylindrical cup that accommodates a flange extending from the rotating portion of the rotary switch would be one embodiment. The switch coupling member may also include a fastener that attaches the switch coupling member to the switch. For example, the switch may include a switch through hole, the switch coupling member may include a coupling member through hole, and the fastener could be a bolt that extends through the switch through hole and the coupling through hole.

The device may include a handle for physical manipulation by a user as the external portion of the extension member. In one embodiment, the switch has a switch structure for direct physical manipulation of the switch and the handle has a handle structure for physical manipulation by a user and the switch structure and the handle structure are functionally equivalent structures.

In one embodiment, an external switch box is disposed outside of the closed housing and the external portion of the extension member extends into the external switch box. The external switch box may then include a lock for preventing manipulation of the external portion of the extension member by an unauthorized user.

Some embodiments of the device may include a stabilizing extension. The stabilizing extension may include a guide member for engaging and supporting the extension member, an anchor assembly for anchoring the stabilizing extension to a portion of the closed housing, and a supporting member extending from the guide member to the anchor assembly and providing support from the closed housing to the extension member.

Some embodiments of the device may have an extension member with an adjustable length and a setting mechanism for setting the adjustable length to a desired length during installation. For example, the extension member may have a first telescoping portion and a second telescoping portion in a telescoping arrangement for adjusting the adjustable length. The setting mechanism may be a removable pin extending through a first hole in the first telescoping portion and an aligned second hole in the second telescoping portion when the adjustable length is locked to the desired length. A bolt may be used as the removable pin and secured with a nut.

Some embodiments of the device include an angular junction in the extension member whereby an angle of the mechanical manipulation of the switch by the switch coupling member is different from an angle of the physical manipulation of the external portion of the extension member. For example, the angular junction may be a gear box for translating rotational motion from the external portion of the extension member to rotational motion of the switch coupling member and the switch. In one embodiment, the angle of the mechanical manipulation of the switch by the switch coupling member and the angle of the physical manipulation of the external portion of the extension member is different by 90 degrees. For example, the axis of rotation of the switch is different by 90 degrees from the axis of rotation of the extension member.

The device may be part of a switch extension kit. The kit could include the switch extension device made of a switch coupling member and an extension member, and an external switch box. The switch extension device may be installed within a closeable housing containing components that are electrically charged when the switch is in the first position and not electrically charged when the switch is in the second position. The extension member could have an external portion that extends outside of the closable housing for access by a user without opening the closed housing and whereby physical manipulation of the external portion of the extension member is mechanically translated to the switch coupling member for mechanically manipulating the switch between at least the first switch position and the second switch position. The kit could also include a stabilizing extension for the switch extension device made of a guide member for engaging and supporting the extension member, an anchor assembly for anchoring the stabilizing extension to a portion of the closable housing, and a supporting member extending from the guide member to the anchor assembly and providing support from the closable housing to the extension member. The kit could include an angular junction for the switch extension device whereby an angle of the mechanical manipulation of the switch by the switch coupling member is different from an angle of the physical manipulation of the external portion of the extension member.

Another embodiment of the invention is a method of installing a switch extension device. A user opens a closable housing containing a switch and components that are electrically charged when the switch is in the first position and not electrically charged when the switch is in the second position. The user then identifies a path for the switch extension device and prepares a permanent opening in the closable housing for the switch extension device to extend from the interior of the closable housing to the exterior of the closable housing. The user mates the switch coupling member of the switch extension device with the switch such that the extension member of the switch extension device extends through the permanent opening in the closable housing and exposes the external portion of the extension member on the exterior of the closable housing. The user then closes the closable housing. The external portion of the extension member may then be accessed by any future user without opening the closed closeable housing and physical manipulation of the external portion of the extension member is mechanically translated to the switch coupling member for mechanically manipulating the switch between at least the first switch position and the second switch position. The method may also include installing an external switch box that is disposed on the exterior of the closed closable housing and the external portion of the extension member extends into the external switch box. Where necessary, the method may also include installing a stabilizing extension for the switch extension device by placing the extension member through a guide member of the stabilizing extension and anchoring the stabilizing extension to a portion of the closable housing, whereby the stabilizing extension provides support from the closable housing to the extension member. In some installations, the path for the switch extension device may include a difference between the angle of the mechanical manipulation of the switch by the switch coupling member and the angle of the physical manipulation of the external portion of the extension member and the switch extension device further comprises an angular junction for translating the physical manipulation of the external portion of the extension member to mechanical manipulation of the switch by the switch coupling member.

Advantageous Effects of Invention

The present invention will provide improved safety for electrical service technicians using the switch extension.

DESCRIPTION OF EMBODIMENTS

The present invention relates to a switch extension that can be installed in a unit of electrical equipment, such as a transformer, to provide an external switch that can be toggled without opening the original housing of the electrical equipment or exposing the technician to live, high-voltage components. Once the switch extension is installed, the external switch is generally placed inside a weatherproof and lockable switch box on the outside of the transformer for safe operation of the internal switch, such as a rotary oil switch. Movement of the external switch is translated through the switch extension to toggle the internal oil switch.

One use of the invention is as an aftermarket modification to transformers that have already been installed and are operating in the field. Due to the variety of transformer housing configurations, individual installations, and preferred access points for the external switch, it is desirable to have a switch extension that is customizable in the field for the particular transformer situation. The switch extension can include one or more adjustable members to control the length of the extension and match the distance between the internal switch and the external switch box. In addition, the switch extension may include an angular adjustment such that the external switch box may be on a housing surface that is not parallel with the internal switch surface. For example, a right angle device may be used to place the external switch on a surface perpendicular to the internal switch surface. Other angular configurations are possible for accommodating unusual housing designs or further translating the external switch location.

The switch extension device may be made out of steel, fiberglass, or other rigid materials that allow the necessary mechanical strength and integrity for reliably operating the internal switch. Use of non-conducting materials provides additional safety benefits in the event that the switch extension comes too close to high voltage components.

FIGS. 1-5show one embodiment of the switch extension device. The switch extension device100includes a switch coupling member110, which is the portion of the device that mechanically engages the internal switch of the electrical equipment for moving it between positions, such as an off and on position. In the embodiment shown, the switch coupling member110is a cylindrical cup that slides over the internal switch and may include additional features for engaging with and being attached to the switch. The cylindrical cup design is made for rotary switches that are generally moved a quarter or half turn between on and off switch positions. In the example shown, the switch coupling member has an internal surface212that defines a shape (round), internal diameter, and cup depth (the internal length of the cylindrical cup) for physically accommodating the switch, which has a rotating portion with an external diameter that is less than the internal diameter of the switch coupling member110. The switch coupling member110further includes a switch manipulation feature, such as a slot114that accommodates a flange on the rotary switch and enables rotation of the switch coupling member110to rotate the switch. Most transformer oil switches are operated by rotating a ½ or ¼ turn clockwise or counter-clockwise to turn them on or off. The switch coupling member must be capable of controllably translating rotational motion to the oil switch to operate it. When the cylindrical cup of the switch coupling member110rotates, the rotating portion of the rotary switch moves as well. The switch coupling member110also includes features for attaching the switch coupling member110to the switch. For example, the switch coupling member110may include a switch coupling through hole116. If the switch has a switch through hole, then a removable fastener, such as a bolt (with or without a nut), may be used to attach to the switch.

FIG. 4shows the switch coupling member110engaged with an example rotary oil switch450. The rotating portion452extends into the switch coupling member110and includes a flange454that is accommodated in the slot114. The switch450also includes a handle456defining a switch through hole458. Using the fastener460, the switch engaging portion is anchored to the oil switch during installation. The fastener460is inserted through the switch coupling through hole116(or holes) in the cylindrical cup, also passing through an opening (switch through hole458) in the oil switch handle456.

The switch coupling member110is attached to an extension member120. The extension member120is the portion of the device that extends from the switch coupling member110to the distal end away from the switch coupling member110. In the embodiment shown inFIGS. 1-5, the extension member120ends in a handle122that would be the external portion of the extension member that would be accessible outside of the housing of the electrical equipment in which the switch extension device100is installed. The end feature of the extension member120, the handle122in the example embodiment, is shaped to make it easier to physically manipulate for turning the switch off or on. The example handle122, uses a simple loop structure that is easy for a user to manipulate directly by hand and is familiar to users because it mimics the loop structure of some switches. Service technicians may also have tools that are designed to engage with such structures. However, a variety of alternative end features are possible, including more ergonomic handles or structures for mating with specific tool interfaces or removable handles. The end portion of the extension member120, whether it is a handle or some other structure, extends outside the housing of the electrical equipment and provides and external switch with actuation tied to the internal switch through the switch extension device100.

Attached to the handle122is an adjustable length body124that comprises the majority of the length of the extension member120in order to traverse the distance from the switch to an exterior wall of the housing of the electrical equipment. The desired length is the length necessary to enable the switch coupling member110to mechanically engage and actuate the switch while allowing the adjustable length body124to extend through the exterior wall and place the handle122outside the electrical equipment housing. In the embodiment shown, the adjustable length body124includes a first telescoping portion126and a second telescoping portion128. The second telescoping portion128fits inside the first telescoping portion126in a telescoping relationship that allows them to move in sliding engagement to adjust the length of the adjustable length body124. While the embodiment shown includes only two telescoping portions, larger number of telescoping portions could be used to achieve the desired variability in length while maintaining the rigidity necessary for the application. A variety of setting mechanisms are available for telescoping bodies, such as friction, magnetic, and twisting locks that maintain the telescoping portions at a desired length. In the embodiment shown, the setting mechanism uses a simple arrangement of evenly spaced through holes, for example through holes130,132, in both telescoping portions. When the through holes are in alignment at the desired length, removable pins134,136are placed through the matched set of through holes in both telescoping portions. In the embodiment shown, the removable pins134,136are threaded bolts that are retained in place using nuts screwed onto their distal ends to ensure that the pins remain in place and the telescoping portions126,128maintain a fixed relationship for the desired length.

The adjustable length body124of the extension member120is attached to an angular junction140. In the example shown, a commercially available one-to-one right angle gear box is used to transfer the direction of the switching perpendicular to the internal oil switch. Rotational motion of the handle122is translated through the adjustable length body124to one of the angular junction connection seats142. The angular junction140translates the motion 90 degrees to a second of the angular junction connection seats244that is attached to the switch coupling member110. Thus, the switch coupling member110rotates based upon rotation of the extension member120.FIG. 4shows the axis of rotation446of the handle122and the axis of rotation448of the rotary switch450on a 90 degree relationship.

In alternate configurations, the adjustable length body124could connect directly to the switch coupling member110, the angular junction140could be between the handle122and the adjustable length body124, or any combination of fixed and adjustable bodies could be present between handle122and angular junction140and/or angular junction140and the switch coupling member110. In one embodiment, a common and detachable attachment mechanism is used between each piece and the user determines the configuration of bodies and angular junctions between the handle122and switch coupling member110as appropriate to their path for the switch extension device during installation.

FIG. 5shows the switch extension device100installed in the housing570of a unit of electrical equipment, such as a pad mounted transformer. The switch coupling member110is mechanically engaged to the rotary switch450of the electrical equipment570, though it has not been fastened in place (a fastening pin has not been inserted into the through hole). The length of the switch coupling member110and the angular junction140define a distance from the switch face panel572for the path of the extension member120. In the example electrical equipment570, the switch face panel572provides access to both the rotary switch450and transformer terminals574,576,578, which are active electrical components that are energized when the rotary switch450is in the on position and de-energized when the rotary switch450is in the off position. The installed switch extension device100follows a path that is clear of the active electrical components. The extension member120traverses the lateral distance from where the switch coupling member110engages the switch450through an opening582in exterior wall580, such that the handle122is outside the housing570. The opening582generally is not a factory standard opening in the equipment housing, but a new opening drilled or cut from the housing570and specifically sized to accommodate the extension member120. The opening582may be made in a side wall or other exterior surface of the housing, which could include being made through a removable panel of the housing, or even through a door panel, vent panel, or other housing feature. For added security, a weatherproof and lockable external switch box590has been installed to cover the handle122. The external switch box590includes a door592for accessing the handle122and a lock594for preventing manipulation of the external portion of the extension member120by an unauthorized user. Because the location of the switch and distance to the exterior wall of the housing will vary among different units of electrical equipment, the ability to customize the length of the extension member120is desirable. Various combinations of bodies (for distance) and angular junctions (for orientation) can enable more complex paths and selective location of the external access to the handle (and placement of the external switch box). InFIG. 5, the closable door584of the housing570is open to display the switch extension device100. The door584would be opened for installation of the switch extension device100, but would be closed (and generally locked) during normal operation of the electrical equipment, including when a service call is initiated. The service technician would only need to open the external switch box590and actuate handle122to turn the switch450from an on position to an off position, powering down the transformer terminals574,576,578before opening the door584or otherwise servicing the electrical equipment.

FIGS. 6-10show an alternate example embodiment of a switch extension device. The switch extension device600is a straight switch extension that includes a similar switch coupling member610and extension member620, but without the intervening angular junction. The switch coupling member610includes the cylindrical cup design with a slot614that accommodates a flange on the rotary switch and enables rotation of the switch coupling member610to rotate the switch. The switch coupling member610also includes a through hole616for fastening the switch extension device600to the switch. The extension member620may be a fixed length body connecting the switch coupling member610to the handle622, which is the external portion of the extension member620. Alternately, the extension member620could be a fully compacted telescoping adjustable length body held to its minimum length by the through bolts shown. Rotation of the handle622is directly translated through the rigid body of the extension member620and the switch coupling member610to the switch, without any need for more complex angular translation.FIG. 8shows the switch extension device600mechanically engaging a rotary switch850.

In addition, the switch extension device600further incorporates an optional stabilizing extension630that is anchored to the ceiling, floor, or another surface of the transformer housing or environment. In the example shown, the stabilizing extension630includes a guide member632for engaging and supporting the extension member620, an anchor assembly634for anchoring the stabilizing extension630to a portion of the housing, and a supporting member636extending from the guide member632to the anchor assembly634and providing support from the housing to the extension member620. The guide member632can be any component for supportively engaging the extension member620while not preventing or obstructing the movement necessary to actuate the switch. In the example embodiment, the guide member632is a pair of arcuate bands with flattened distal ends that can be used to removably attach them to one another to define a ring through which the extension member620can extend. This design enables the stabilizing extension630to easily be added or removed from the switch extension device600. The anchor assembly634can include any mechanism for attaching the stabilizing extension to the housing. In the example embodiment, the anchor assembly is magnetized such that it will attach itself to the ferrous metal of the housing in whatever location is needed for installation. Other alternatives include the use of an adhesive pad, separately applied adhesive, or mechanical attachment, such as the use of through holes in both the anchor assembly and the housing accommodating nut and bolt fasteners. The supporting member636can be any structural body for fixing the distance between the guide member632and the anchor assembly634. It can be a fixed length member, as shown in the example. By using a threaded body, it can be cut to the desired length and the guide member632and the anchor assembly634are attached using a compatible threaded attachment. Alternatively, it can be an adjustable body, using a telescoping configuration or similar approach. The stabilizing extension630may or may not be needed to support the extension member620, depending on the configuration of the installation and whether adequate support can be provided at the transformer housing through point or external switch box. The stabilizing extension may also be used with some configurations of an angled switch extension device, such as switch extension device100inFIGS. 1-5.

FIG. 10shows a cutaway view (where the panel of the housing that would normally enclose the access compartment has been removed) of the switch extension device600installed in the housing1070of a unit of electrical equipment, such as a pad mounted transformer. The switch coupling member610is mechanically engaged to the rotary switch850of the electrical equipment1070, though it has not been fastened in place (a fastening pin has not been inserted into the through hole). The length of the switch coupling member610and the extension member620define a distance from the switch face panel1072across the width of the access compartment1074and through exterior wall1076. With the straight extension, the path of the switch extension device600will frequently extend through the closable access door in exterior wall1076.FIG. 10shows the installed switch extension device600with the closable access door in the closed position (and this indistinguishable from the walls of the housing). In the example electrical equipment1070, the switch face panel1072provides access to both the rotary switch850and transformer terminals1078, which are active electrical components that are energized when the rotary switch850is in the on position and de-energized when the rotary switch850is in the off position. The installed switch extension device600follows a path that is clear of the active electrical components. The extension member620traverses the lateral distance from where the switch coupling member610engages the switch850through an opening1080in exterior wall1076, such that the handle622is outside the housing1070. For added security, a weatherproof and lockable external switch box1090has been installed to cover the handle622. The external switch box1090includes a door1092for accessing the handle622and a lock1094for preventing manipulation of the external portion of the extension member620by an unauthorized user. The extension member620is supported by the stabilizing extension630that is attached to the housing1070by the anchor assembly634.

In one embodiment, the components of the switch extension could be provided to an installer as a kit. In one version of the kit, a switch extension device, such as the straight extension device described with regard toFIGS. 6-10or the angled extension device described with regard toFIGS. 1-5, along with the external switch box and all needed fasteners. An alternate embodiment of the kit would provide various components of a switch extension device and enable the installer to customize the switch extension device for their application. For example, the kit could include one or more switch coupling members (perhaps with alternate configurations for engaging different types of switches), one or more handles or other end features, one or more fixed or adjustable length bodies, and one or more angular junctions that can be assembled into a switch extension for the desired path. The kit may also include a stabilizing extension for use if needed and a lock compatible with the external switch box.

FIG. 11shows a method of installing a switch extension. The switch extension installed may be used for the straight extension device described with regard toFIGS. 6-10, the angled extension device described with regard toFIGS. 1-5, a switch extension kit, or an alternate configuration of a switch extension device. In step1110, an installer opens the housing of the electrical equipment, generally using a door or removable access panel for accessing the safety switch. For example, a service technician may open the transformer terminal cabinet of a pad mounted transformer. In step1115, the installer determines the location of the internal switch within the housing. In step1120, the installer determines the location of the exterior access point from which a user will be able to physically access the switch extension without opening the housing. In step1125, based on the location of the internal switch and the exterior access point, the installer determines a path for the switch extension device. In step1130, the installer prepares and opening in the housing, such as a through hole cut in the transformer housing at the desired location for the exterior access point. If the switch extension device being used includes multiple arrangements of components or adjustable length members, the installer configures the device in step1135. If a fixed switch extension, straight or angled, is being used, the location of the external access point will be defined by the location of the internal oil switch and the geometry of the switch extension device and step1135is unnecessary. If an adjustable switch extension is being used, then the length of the primary extension member, any secondary extension member, and angular junction (if adjustable) are set to match the desired path from the internal switch to the external access point. In step1140, the switch extension is mated to the internal switch to enable mechanical manipulation of the switch by the switch extension. In some embodiments, the installer will fasten the switch extension to the switch. In step1145, the switch extension device is extended through the prepared opening such that a portion of its end, generally a handle, is accessible from the exterior of the housing. Depending on the configuration of the switch extension, the geometry of the housing, and the preferences of the installer, steps1140and1145may be reversed as needed. If the switch extension device requires additional support, one or more stabilizing extensions securing the switch extension device to the housing may be installed in step1150. In most installation, the installer will attach an external switch box to the housing to cover the opening at the external access point and the external portion of the switch extension device in step1155. When the switch extension device is in place and the installer has confirmed that physical manipulation of the external portion of the extension member of the device is mechanically translated to the switch coupling member of the device for mechanically manipulating the switch between at least the first switch position and the second switch position, correlating to on and off, the housing is closed (and preferably locked) in step1160. Once installed, a service technician may access and operate the external switch to turn the internal switch on and off (between a first switch position and a second switch position) without opening the housing of the electrical equipment.