Electrical switchgear must be de-energized before maintenance personnel can work on the equipment. De-energizing the switchgear typically involves opening a circuit breaker, either remotely or at the switchgear, to de-energize the equipment. The maintenance personnel may also take electrical measurements to ensure that the circuit(s)/equipment has been properly de-energized before working on the equipment.
The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. Also, the following detailed description does not limit the invention.
Embodiments described herein provide switchgear with viewing windows to aid personnel in determining whether a circuit is energized. For example, in one embodiment, a viewing window is provided in each phase of switchgear to allow personnel to see a break in an electrical circuit when a circuit breaker or switch has been opened. In addition, in some implementations, a second viewing window is provided in each phase of the switchgear to allow personnel to see whether a ground connection has been made. The switchgear may also include interlocks, such as mechanical interlocks, to ensure that the equipment is de-energized and/or grounded in a particular sequence.
Cabinet 110 includes interlocking control mechanisms that prevent operating handles 112 and 114 from being operated (e.g., opened and closed) out of sequence. For example, in one implementation, operating handle 112 may be connected via a mechanical interlock/link that prevents ground operating handle 114 from being closed while visible break operating handle 112 is in the closed position. In addition, the mechanical interlock between visible break operating handle 112 and ground operating handle 114 may prevent visible break operating handle 112 from being closed while ground operating handle 114 is in the closed position.
Each of tubes 120, 122 and 124 may include an outer shell made of an insulating material, such as ethylene propylene diene monomer (EPDM) or some other type of rubber. Each of tubes 120, 122 and 124 is illustrated as containing two individual members/tubes. Each of the individual members/tubes in tubes 120, 122 and 124 is electrically isolated from the other tube and may include a separate circuit breaker or switch to open and close an electrical connection or a ground connection. For example, the left tube of the two tubes included in tube 124 (labeled 124A) may include a ground connection switch used to open/close a ground connection to ground switchgear 100 to, for example, ground stud 160, which may be connected to an external ground. In some implementations, each tube 120, 122 and 124 may include a ground stud connected to an external ground, similar to ground stud 160. The right tube labeled 124B may include a circuit breaker or switch to open/close an electrical connection supplying power to a load via a conductor coupled to bushing 134, as described in detail below.
Each of tubes 120, 122 and 124 also includes two viewing windows. For example, tube 120 includes viewing windows 140 and 150, tube 122 includes viewing windows 142 and 152 and tube 124 includes viewing windows 144 and 154. Each of windows 140-154 may be circular or oval shaped and be made of a transparent plastic, glass or other transparent material that allows personnel to see inside the corresponding tube. In one implementation, viewing windows 140, 142 and 144 are associated with ground contacts and viewing windows 150, 152 and 154 are associated with electrical contacts to a line/load. When visible break operating handle 112 is moved from the closed position illustrated in
As described above, each of insulating tubes 120, 122 and 124 includes an electrical connection and a ground connection. For example,
As illustrated, viewing window 144 allows personnel to see whether a ground connection is made and viewing window 154 allows personnel to see whether an electrical connection or a visible open is present in the electrical circuit. For example, the ground circuit in tube 124A is shown in the open position in which the electrical ground contact/pin 182 is not mated/connected to female contact 184, thereby showing an open area in the ground circuit that is viewable through viewing window 144. The electrical circuit in tube 124B is also shown in the open position, in which the electrical contact/pin 192 is not mated/connected to female contact 194. When the switch in tube 124A (or 124B) closes, the contacts for that switch close.
In some implementations, the area on the back side of tube 124B may be green in color to provide a further visual indication that the electrical circuit is open, as described in more detail below. In addition, tubes 124A and 124B may be filled with an insulating fluid. For example, in one implementation, the chambers labeled 129A and 129B are filled with silicone fluid or some other type of fluid or gel that acts as an insulator.
As discussed above, switchgear 100 may be connected to additional switchgear that provides power to switchgear 100. For example,
Switchgear 205 also includes interlocking mechanisms with switchgear 100 to ensure that the circuits connected to swithgear assembly 200 are not opened/closed out of sequence. For example, MVI operating handle 212 includes a mechanical interlock with visible open operating handle 112 to ensure that visible open operating handle 112 cannot open unless MVI operating handle 212 is in the open position.
In one implementation, the interlocking mechanism includes interlocking metal portions that extend from MVI operating handle 212 and visible open operating handle 112. For example, referring to
For example, visible open operating handle 112 includes a metal plate 216 (referred to as interlock 216) that is welded/connected to a lower portion of visible break operating handle 112. Interlock 216 includes a planar portion that extends from visible break operating handle 112 and a portion labeled 216A that extends perpendicularly in an outward direction from the planar portion. Portion 214A of interlock 214 overlaps or interlocks with portion 216A of interlock 216. As a result, visible open operating handle 112 cannot be pulled forward to move to the open position unless MVI operating handle 212 is in the open position. That is, interlocks 214 and 216 prevent visible open operating handle 112 from moving when MVI operating handle 212 is in the closed position illustrated in
Next, personnel may open visible break operating handle 112, as illustrated in
For example,
Next, personnel may close ground operating handle 114 by moving ground operating handle 114 in the upward direction, as illustrated in
Referring to
In this manner, interlocks between switchgear 100 and switchgear 205 ensure that various breakers and/or switches cannot be operated out of sequence. In addition, viewing windows allow personnel to determine whether the circuits are de-energized before working on the equipment. To re-energize switchgear 200, personnel may perform the sequence of operations described above in reverse order.
For example, ground switch 114 may be moved from the closed position to the open position. Next, visible break operating handle 112 may be moved from the open position to the closed position. Lastly, MVI operating handle 212 may be moved from the open position to the closed position. Similar to the discussion above regarding de-energizing switchgear assembly 200, the mechanical interlocks between MVI operating handle 212 and visible open operating handle 112, and the mechanical interlocks between visible open operating handle 112 and ground operating handle 114 prevent personnel from performing the re-energizing process out of the proper sequence. For example, the mechanical interlock between ground operating handle 114 and visible break operating handle 112 prevents visible break operating handle 112 from being moved to the closed position when ground operating handle 114 is in the closed position. Similarly, interlocks 214 and 216 prevent MVI operating handle 212 from being moved to the closed position when visible open operating handle 112 is in the open position.
As described above, the visible break and visible ground circuit breakers/switches may be implemented in a 3-phase assembly, as illustrated in
In addition, in some implementations, switchgear 100 may include a visible break assembly, without including a visible ground assembly (or vice versa). In this implementation, each of tubes 120, 122 and 124 may include only a single tube that houses an electrical switch, as opposed to two individual tubes housing both an electrical switch and a ground switch. For example, in such an implementation, tube 124 will include only tube 124B which will allow personnel to view the state of the electrical switch (e.g., opened or closed). In addition, in this implementation, visible open operating handle 112 interlocks with MVI operating handle 212, but may not interlock with a ground operating handle, such as ground operating handle 114. For example, in some implementations, switchgear 100 may not include a ground operating handle.
Tube 910 may be made of overmolded insulating rubber and a conductive outer jacket. Tube 910 may also be surrounded by an insulating rubber (not shown), such as EPDM, that protects the components of visible open switch 900. Contact 920 may include a conductive contact or pin that moves within chamber 926 to make contact with female electrical contact 924 when switch 900 is closed.
Contact 920 may be coupled to actuator rod 940 via insulator or linking rod 930. Actuator rod 940 and switch 900 are shown in
The upper portion of visible open switch 900 includes closed cell foam volume compensator 970 and static seal 972. The lower portion of closed cell foam volume compensator 970 abuts a metallic perforated plate 956. The upper portion of switch 900 also includes fluid passage 954 and the lower portion of switch 900 includes fluid passage 955 that allow fluid to be displaced when actuating rod 940 moves linking rod/insulator 930 and electrical contact 920 to close switch 900. For example, since switch 900 is housed in an enclosed cell/chamber, movement of electrical contact 920 causes displacement of the silicone fluid. Closed cell foam volume compensator 970 may be made of a compressible foam or other material that compresses when the silicon fluid is displaced by the closing of switch 900, thereby ensuring that the silicone fluid does not escape via the various seals and fill ports (e.g., seals 944 and 946 and ports 942). In other implementations, a diaphragm may be used in place of closed cell foam volume compensator 970 that functions to compress or move when fluid is displaced by the closing of switch 900.
Viewing window 980 may correspond to one of viewing windows 150, 152 or 154 (or viewing windows 140, 142 or 144) in
In addition, in this implementation, a portion of contact 920 may include a band of reflective tape or a collar that is red in color at the area labeled 984 in
In some implementations in which a ground switch is used, no color indicators may be used for the ground switch. That is, personnel may simply look in the appropriate viewing window to determine whether the ground connection is open or closed. Alternatively, in some implementations, color indicators may be used for the ground switch. In such implementations, the colors may be reversed. For example, when the ground switch is closed, a portion of the ground contact may be green in color to indicate that the ground switch is closed/grounded. When the ground switch is open, the back portion of the switch may be red in color to indicate that the ground switch is open/ungrounded.
As described above, in some implementations, switchgear similar to switchgear 100 may include a visible break assembly, without including a visible ground assembly (or vice versa). For example,
Each of tubes 1120, 1122 and 1124 may be similar to tubes 120, 122 and 124 illustrated in
Each of tubes 1120, 1122 and 1124 includes one viewing window associated with its corresponding electrical switch. For example, tube 1120 includes viewing window 1140, tube 1122 includes viewing window 1142 and tube 1124 includes viewing window 1144. Each of windows 1140, 1142 and 1144 may be circular or oval shaped and be made of a transparent plastic, glass or other transparent material that allows personnel to see inside the corresponding tube. When visible break operating handle 112 is moved from the closed position illustrated in
Viewing windows 1142 and 1144 are illustrated in
Each of tubes 1120, 1122 and 1124 may also include voltage detection points 1160, 1162 and 1164, as illustrated in
The foregoing description of exemplary implementations provides illustration and description, but is not intended to be exhaustive or to limit the embodiments described herein to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the embodiments.
For example, implementations described herein have been described with respect to use of switchgear in either a three phase or single phase implementation. In either case, implementations described herein may be used with low, medium or high voltage equipment, such as switchgear that is used with 15 kilovolt (kV), 25 kV, 35 kV or higher (or lower) voltages.
In addition, embodiments described above refer to using various operating handles (e.g., MVI operating handle 212, visible break operating handle 112 and ground operating handle 114) to control various operations. In other implementations, other types of mechanical mechanisms may be used to ensure that various breakers and/or switches cannot be operated out of sequence. For example, the mechanical interlocks may not be included on or attached to the operating handles themselves. As one example, switchgear 205 (or switchgear 100) may include a pin that can only be pulled when MVI operating handle 212 is in the open position. The pin may also be coupled to visible break operating handle 112 to prevent visible break operating handle 112 from being moved to the open position when the pin has not been pulled. Similar pin interlock(s) may be used between visible break operating handle 112 and ground operating handle 114 to prevent operation of various switches and/or ground connections that is not in accordance with the desired sequence of operations. It should be understood that other types of mechanical interlocks and/or controls may be used to prevent out of sequence operation. In each case, personnel may also view the status of the various switches and connections via one or more viewing windows.
Further, embodiments described above refer to using mechanical type interlocks to control various operations. In other implementations, the various switches/breakers may be motor operated and may be opened and closed via control buttons located on switchgear assembly 200 or located remotely from switchgear assembly 200. For example, instead of manually moving MVI operating handle 212 from the closed position to the open position, personnel may press a button on switchgear 205. Similarly, personnel may press a button on switchgear 100 to open and close visible break switches and ground switches. In this case, the mechanical interlocks described above for MVI operating handle 212, visible break operating handle 112 and ground operating handle 114 may be replaced with electrical interlocks and/or controls that prevent operations that do not correspond to the proper operating sequence. In each case, personnel may verify the state of the switches via the viewing windows.
In addition, switchgear 100 is illustrated as including switches 900 or 1000 (
Further, implementations described herein refer to use of switchgear assembly 100 connecting/interface with switchgear assembly 205. In some implementations, switchgear 100 may be used in situations in which switchgear 205 is already installed. In such situations, switchgear 100 may be provided without requiring any or significant changes to existing switchgear 205.
Still further, implementations described above include use of visible open switches, such as switches 900 or 1000 that include a male contact that moves in a longitudinal direction within a chamber to make contact with a female contact. In other implementations, a “flag” type contact may be used to close, open and/or ground a circuit. For example, a rotating flag/electrical contact may be coupled to a rotating shaft. In one implementation, one side of the rotating flag is red in color, an edge portion of the flag is green in color, and the other side of the rotating flag is yellow in color. When a visible break operating handle is moved to a closed position, the rotating shaft may rotate the flag/electrical contact to close the switch/circuit breaker. In this case, the red side of the rotating flag may be visible through the viewing window, indicating that the circuit is closed. When the visible break operating handle is moved to the open position to open the switch, the rotating shaft rotates the flag approximately 90 degrees so that the edge portion of the flag is visible. In this case, the green edge of the rotating flag will be visible through the viewing window, indicating that the circuit is open. When the ground handle is moved to the grounded/closed position, the rotating shaft rotates the flag another 90 degrees to ground the circuit. In this case, the yellow side of the rotating flag may be visible through the viewing window, indicating that the circuit is grounded. In this manner, three switch positions (i.e., closed, open and grounded) may be visible to personnel via a rotating flag type contact.
Although the invention has been described in detail above, it is expressly understood that it will be apparent to persons skilled in the relevant art that the invention may be modified without departing from the spirit of the invention. Various changes of form, design, or arrangement may be made to the invention without departing from the spirit and scope of the invention. Therefore, the above mentioned description is to be considered exemplary, rather than limiting, and the true scope of the invention is that defined in the following claims.
No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.
This application claims priority under 35 U.S.C. §119 based on U.S. Provisional Patent Application No. 61/950,996 filed Mar. 11, 2014, the disclosure of which is hereby incorporated herein by reference.
Number | Date | Country | |
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61950996 | Mar 2014 | US |