GB2138635A

GB2138635A - Metal Enclosed Switchgear

Info

Publication number: GB2138635A
Application number: GB08410084A
Authority: GB
Inventors: Toshitaro Yamamoto
Original assignee: Meidensha Corp; Meidensha Electric Manufacturing Co Ltd
Current assignee: Meidensha Corp; Meidensha Electric Manufacturing Co Ltd
Priority date: 1983-04-19
Filing date: 1984-04-18
Publication date: 1984-10-24
Also published as: GB2138635B; JPS59164412U; IN162148B; SG2888G; JPS6341769Y2; MY100373A; GB8410084D0

Abstract

Metal enclosed switchgear includes a box (2) with a bottom (2a), a circuit breaker assembly (8) being freely carried into or out of the box (2) on rollers (9) rolling on the bottom (2a), an earthing switch (18), a rod (23) for operating the switch (18) and a mechanical interlock (A) between the breaker (8) and the switch (18). The interlock (A) includes a roller stopper operating rod (29) rigidly secured to the earth switch operating rod (23), a movable roller stopper (35) operated by the roller stopper operating rod (29) to be rotated extending into a path on the bottom (2a) of a roller (9) and a stationary roller stopper (36) rigidly secured to the bottom (2a) to contact against the movable roller stopper (35). Thus, an impact which is effected by an inertia in carrying-in of the breaker (8) can barely destroy the interlock (A). Additionally, since the interlock (A) consists of mechanical elements alone, a part of the interlock (A) which is disordered or destroyed is apparent and ready to repair. <IMAGE>

Description

SPECIFICATION Metal Enclosed Switchgear The present invention relates to a metal enclosed switchgear comprising a circuit breaker of a pullout type (hereinafter, referred to as a circuit breaker), an earthing switch which earths a load circuit when necessary, and an interlock between the circuit breaker and the earthing switch.

An earthing switch of a metal enclosed switchgear serves to earth for safety such electric devices as belong to a load circuit connected to a circuit breaker, prior to a maintenance and/or an inspection of the electric devices. It is an interlocking condition between the earthing switch and the circuit breaker that the latter will not be carried to an electrically connected position thereof during the former is closed.

Conventionaily, various interlocks of a mechanical or electrical system have been presented. However, on one hand the interlocks of the conventional electrical system possess a drawback that they necessitate a long time for an inspection or a repair when an electric part thereof expires or is caused to be broken. On the other hand, the interlocks of the conventional mechanical system possess a drawback that they are easily destroyed if the circuit breaker has a large interruption capacity and a weight, because the force of the carrying-in inertia of the circuit breaker is large in carrying-in thereof. Indeed, the interlocks of both the conventional systems have insured a poor reliability of the interlock between the earthing switch and the circuit breaker.

A primary object of the present invention is to provide a metal enclosed switchgear including a mechanical interlock, which possesses a mechanical strength sufficient to be barely destroyed by the force of the carrying-in inertia of a circuit breaker not only where the circuit breaker has a large interruption capacity and weight but also where it has a small interruption capacity and weight, between the circuit breaker and an earthing switch.

Another object of the present invention is to provide a metal enclosed switchgear including a mechanical interlock, a part of which is easy to find out and ready to repair- if it is disordered and/or destroyed, between a circuit breaker and an earthing switch.

To accomplish the above objects, the metal enclosed switchgear includes a box with a bottom which has a perpendicular partition and a circuit breaker accommodating chamber defined in front of the partition, a pair of disconnectors fixed to and through the partition; one disconnector of the pair being connected to a power supply bus and the other disconnector of the pair to a load bus, an earthing switch connected to the load bus, an earthing switch operating rod, a circuit breaker, which has a pair of connecting rods electrically connected to and disconnected from the disconnectors and a plurality of rollers rolling on the bottom of the box, being capable for carrying in or out of the circuit breaker accommodating chamber, and an interlock between the earthing switch and the circuit breaker, the interlock including a roller stopper operating rod rigidly secured to the earthing switch operating rod, an intermediate lever partially rotated by the roller stopper operating rod, a rotating shaft rigidly secured to the intermediate lever, a movable roller stopper rigidly secured to the rotating shaft and operated to be extended into a path on the bottom of the box of the rollers of the circuit breaker, and a stationary roller stopper rigidly secured to the bottom of the box so as to contact the movable roller stopper in its extended position.

Metal-clad switchgear constructed in accordance with the invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 shows basically a side view of the interiors of a metal enclosed switchgear of the present invention; Fig. 2 shows a plan view of the interlock of Fig.

1; Fig. 3 shows a detailed plan view illustrative of the operation of the interlock of Fig. 1; Fig. 4 shows a detailed side view corresponding to Fig. 3 illustrative of the operation of the interlock of Fig. 1.

Referring to the attached Figs. 1 to 4, a preferred embodiment of the present invention will be hereinafter described in detail.

For better understanding of the present embodiment a basic arrangement of a metal enclosed switchgear 1 containing gn interlock A will be first described in conjunction with Fig. 1.

The metal enclosed switchgear 1 includes a box 2, the inside of which is divided into a chamber 3 for accommodating a circuit breaker at its front, a chamber 4 for accommodating a power supply bus at its rear and above, and a chamber 5 for accommodating a load bus at its rear and below.

A perpendicular partition 6 is provided between the circuit breaker accommodating chamber 3 and the power supply bus accommodating chamber 4 and load bus accommodating chamber 5. A horizontal partition 7 is provided between the power supply and load bus accommodating chambers 4 and 5.

A withdrawable circuit breaker 8 is placed within the circuit breaker accommodating chamber 3. The circuit breaker 8 is provided with a plurality of rollers 9 rolling on a bottom 2a of the box 2.

A pair of disconnectors 12 and 13 is fixed to and through the perpendicular partition 6 behind the circuit breaker 8. One disconnector 12 extends into both the circuit breaker and power supply bus accommodating chambers 3 and 4.

The other disconnector 1 3 extends into both the circuit breaker and load bus accommodating chambers 3 and 5. A terminal (not shown) of the power supply bus 14 is held within the one disconnector 12. On the other hand, a terminal (not shown) of the load bus 1 5 is held within the other disconnector 13.

A pair of connecting rods 16 and 17, each having an electrical plug (not shown) which is pullable from the terminal of the power supply bus 14 or load bus 15, is provided extending toward the disconnectors 12 and 13. The electrical plugs are connected to a pair of electrodes (not shown) of the circuit breaker 8.

An earthing switch 18 is mounted to a part facing the load bus accommodating chamber 5 of the perpendicular partition 6. The earthing switch 18 includes at its rear end a stationary blade 19 extending downward. The stationary blade 19 is connected to the load bus 1 5 via a connecting bus 10. The earthing switch 1 8 also includes a movable blade 20 which is to be thrown in or out of the stationary blade 19. The movable blade 20 is rigidly attached to a fulcrum end of an operating end lever 21.A distal end of the operating end lever 21 is pivotably attached to the rear end of the earthing switch operating rod 23 which extends to a front of the box 2, by means of a stationary pivot 22 being immovable relative to the earthing switch 1 8. As apparent from Fig. 2, the earthing switch operating rod 23 is situated apart from a side of the circuit breaker 8.

The movable blade 20 is perpendicularly downwardly extended in an opened position of the earthing switch 1 8 and is rotated through about 900 counterclockwise in Fig. 1 during the earthing switch 1 8 shifts from the opened position thereof to a closed position thereof. The earthing switch operating rod 23 is longitudinally movable. The front end thereof is connected to one end of an L-shaped handling end lever 24 by means of a movable pivot 25. A corner of the handling end lever 24 is supported by a stationary pivot 26 immovable relative to the box 2. The handling end lever 24 is rotated by an operator via an operating handle 24a. The handling end lever 24 is placed at a broken-lined position in Fig.

1 when the earthing switch 1 8 is opened. On the other hand, the handling end lever 24 is placed at a phantom-lined position when the earthing switch 1 8 is closed.

In the arrangement of the metal enclosed switchgear 1, an interlock A which is installed within the circuit breaker accommodating chamber 3 is mechanically interlocked with the earthing switch operating rod 23.

An arrangement of the interlock A will be hereinafter detailed. A mount 28 is rigidly secured at a substantially mid-portion of the earthing switch operating rod 23 thereto by means of a pair of V-bolt and nut assemblies 27. A roller stopper operating rod 29 is attached extending downwardly by welding to the mid-axial portion of the mount 28.

As shown in Fig. 3, an intermediate lever 30 which includes an elongated opening 31 at its one end is associated with the roller stopper operating rod 29 passing through the elongated opening 31. The upper end of a rotating shaft 32 is inserted into a sleeve 30a fixedly attached to the other end of the intermediate lever 30 and is rigidly secured to the same by means of a knock pin 34.

As shown in Figs. 1 and 4, the lower end of the rotating shaft 32 is held by a bearing 33 fixed to the bottom 2a of the box 2. A roller stopping lever 35 in a square pillar form is rigidly attached to the lower end of the rotating shaft 32.

A stationary roller stopper 36 in a square pillar form is fixed by bolts 37 or welding to the bottom 2a near the bearing 33. The stationary roller stopper 36 serves to apply such a reaction to the roller stopping lever 35 against a force applied thereto by the circuit breaker 8 as to position the roller stopping lever 35 at its roller stopped position as shown by a solid-lined roller stopping lever 35 in Fig. 3, if one of the rollers 9 of the circuit breaker 8 which is moving to its electrically connected pdsition contacts the roller stopping lever 35, which is fully extended to the roller stopped position.

Now, the operation of the interlock A will be described hereinafter.

In Fig. 1 , the earthing switch 18, when the operating handle 24a is placed at its lower position and the earthing switch operating rod 23 is placed at the most backward position as shown in a solid line, is opened because the movable blade 20 is separated from the stationary blade 1 9. In this state, the roller stopping lever 35 is located at the phantom-lined position in Fig. 3.

Thus, the circuit breaker 8 will be freely carried into or out of the circuit breaker accommodating chamber 3. In this state, the circuit breaker 8 will be freely carried out toward the phantom-lined electrically disconnected position in Fig. 1, on the other hand into the solid-lined electrically connected position in Fig. 1.

On the other hand, in Fig. 1, the earthing switch 18, when the operating handle 24a is placed at its upper position and the earthing switch operating rod 23 is placed at the most forward position as shown in the phantom line, is closed because the movable blade 20 contacts the stationary blade 1 9 as shown in the phantom line. In this state, the roller stopping lever 35 is located at the solid-lined position in Fig. 3. Thus, the circuit breaker 8, once pulled out of the circuit breaker accommodating chamber 3, will not be carried into the electrically connected position because the one of the rollers 9 is stopped to roll by the roller stopping lever 35 contacting the stationary roller stopper 36. In conclusion, the above-mentioned condition of interlock is satisfied between the circuit breaker 8 and the earthing switch 18.

Claims

1. A metal enclosed switchgear comprising: a box with a bottom which has a perpendicular partition and a circuit breaker accommodating chamber defined in front of the perpendicular partition; a pair of disconnectors fixed to and through the perpendicular partition, one disconnector of said pair being connected to a power supply bus and the other disconnector of said pair to a load bus; an earthing switch being connected to the load bus; an earthing switch operating rod for said earthing switch; a circuit breaker, which has a pair of connecting rods electrically connected to and disconnected from said disconnectors and a roller rolling on the bottom of said box, being capable for carrying into or out of the circuit breaker accommodating chamber; and an interlock between said earthing switch and said circuit breaker, characterized in that said interlock includes a roller stopper operating rod for the roller rigidly secured to said earthing switch operating rod, a movable roller stopper being operated by said roller stopper operating rod to be rotated extending into a path on the bottom ofsaid box of the roller and a stationary roller stopper rigidly secured to the bottom of said box so as to contact said movable roller stopper in the position extended into the path of the roller.

2. A metal enclosed switchgear as defined in ciaim 1, characterized in that an intermediate lever is pivotably connected to said roller stopper operating rod and that a rotating shaft which is rigidly secured to the fulcrum end of said intermediate lever has said movable roller stopper rigidly secured thereto.

3. Metal-clad switchgear substantially as herein described with reference to, and as illustrated by, the accompanying drawings.