GB2126011A

GB2126011A - Drawout electric switchgear

Info

Publication number: GB2126011A
Application number: GB08322622A
Authority: GB
Inventors: Sueichi Kida; Toshitaro Yamamoto; Toshifumi Takahashi
Original assignee: Meidensha Corp; Meidensha Electric Manufacturing Co Ltd
Current assignee: Meidensha Corp; Meidensha Electric Manufacturing Co Ltd
Priority date: 1982-08-30
Filing date: 1983-08-23
Publication date: 1984-03-14
Also published as: SG56687G; IN159357B; GB2126011B; MY8700692A; GB8322622D0; JPS5937807U

Abstract

A shuttering apparatus for preventing access to live conductors in an enclosed switchboard housing a truck-mounted circuit breaker (1) includes a pair of upper and lower shutter plates (24A, 24B), the upper shutter plate (24A) covering a surface (2A') on the circuit breaker side of upper bushings (2A) located at an upper portion of a grounded partition wall (3) and connected to a power supply bus (4) and the lower shutter plate (24B) covering a surface (2B') on the circuit breaker side of lower bushings (2B) located at a lower portion the partition wall (3) and connected to a load cable (6). The upper shutter plate (24A) is pivoted upward and, on the other hand, the lower shutter plate is pivoted simultaneously downward when the circuit breaker is withdrawn from the enclosed switchboard. <IMAGE>

Description

SPECIFICATION Shuttering apparatus in an enclosed switchboard The present invention relates generally to a shuttering apparatus in an enclosed switchboard in which a truck-mounted circuit breaker is housed and particularly to the shuttering apparatus provided within the enclosed switchboard for quickly shuttering a pair of bushings, located longitudinally on a grounded partition wall, the pair of bushings providing intermediate means for connecting stationary and movable electrode conductive connectors extended from the truck-mounted circuit breaker with a high-voltage power supply bus and load cable bus, when the truck-mounted circuit breaker is carried out of the enclosed switchboard so as to prevent an operator or any other person from directly contacting such pair of bushings.

In general, it is necessary to provide a safety means within such an enclosed switchboard which can house a truck-mounted circuit breaker, in order to prevent an operator or any other person from erroneously contacting or approaching a power supply bus bars, a bushing connected to the power supply bus, and a portion of a load bus which receives a high voltage, after the operator has carried the above-described truck-mounted circuit breaker out of the enclosed switchboard for maintenance or inspection work.

A shuttering apparatus has been proposed as the safety means described above. The enclosed switchboard incorporating such a shuttering apparatus will be described hereinbelow with reference to Fig. 1 prior to the detailed description of a previously proposed shuttering appartus.

Fig. 1 is an overall view of the enclosed switchboard.

The enclosed switchboard ES in which the truck-mounted circuit breaker 1 is housed is usually partitioned into three housings; i.e., a circuit breaker housing A, a power supply bus housing B, and a load cable housing C. In the power supply bus housing B, a power supply bus 4 and branch bus 5 for connecting the power supply bus 4 to upper bushings 2A aligned laterally are disposed. In the load cable housing C, load cable bus 6 for connecting to a load is disposed.

The above-described upper and lower bushings 2A and 2B are a pair of upper and lower bushings 2A and 2B, the upper bushings 2A being connected to the power supply bus 4 in the power supply bus housing B via the branch bus 5 and the lower bushings 2B being connected to the load via the load cable bus 6 in the load cable housing C. (This is the case of poly-phase power supply).

In the above-described circuit breaker housing A, the previously proposed shuttering apparatus denoted by 7 in Fig. 1 is disposed so as to cover surfaces of truck-mounted circuit breaker sides of the pair of upper and lower bushings 2A and 2B when the truck-mounted circuit breaker 1 is carried out of the enclosed switchboard ES with stationary and movable electrode conductive connectors 1A and 1 B horizontally extended from the truck-mounted circuit breaker 1 disconnected from the pair of upper and lower bushings 2A and 2B and so as to uncover the surfaces of the truckmounted circuit breaker side of the pair of upper and lower bushings 2A and 2B when the truckmounted circuit breaker 1 is carried into the enclosed switchboard ES before the stationary and movable electrode conductive connectors 1A and 1 B thereof are connected respectively to the pair of upper and lower bushings 2A and 2B.

In other words, simultaneously when the truckmounted circuit breaker 1 is carried out of the circuit breaker housing A of the enclosed switchboard ES and accordingly the stationary and movable electrode conductive connectors 1A and 1 B of the truck-mounted circuit breaker 1 are disconnected from the pair of upper and lower bushings 2A and 2B, the shuttering apparatus 7 automatically actuates a pair of upper and lower shutter plates to place on the corresponding front surfaces of the pair of upper and lower bushings 2A and 2B which fit the tips of the stationary and movable electrode conductive connectors 1 A and 1 B of the truck-mounted circuit breaker 1 thereinto, thus the front surfaces of the pair of upper and lower bushings 2A and 2B being not exposed to allow the operator or any other person to come in easy touch therewith.

Next, the previously proposed shuttering apparatus will be described with reference to Fig.

1 through Fig. 3(B) in detail hereinbelow.

Figs. 2 through 3(B) show the previously proposed shuttering apparatus which was filed in Japan dated August 12, 1981.

An actuation lever 8 comprising two substantially inversed-triangular shaped plate members is provided at a lower portion of the shuttering apparatus 7. A roller 10 rotatably supported by a horizontally extended axle 9 located at a lower apex portion of each plate member constituting the actuation lever 8 is projected from the lower apex portion thereof.

Each plate member of the actuation lever 8 has one upper apex portion 11 thereof as shown in Fig. 2, the upper apex portion 11 thereof being pivotally supported by another axle 0,. The axle 0, is attached to both side walls of the enclosed switchboard ES in the circuit breaker housing A.

The roller 10 is projected in the course of movement of the truck-mounted circuit breaker 1 and is stationed below an upper surface 1 a of a truck 1 c shown in Fig. 1 fixedly mounting the circuit breaker 1 so that the roller 10 can always rotate and slide about the axle 9 on the upper surface 1 a of the truck 1 C from an oblique edge 1 b at the trailing end of the truck 1 C when the truck-mounted circuit breaker 1 is carried into or out of the circuit breaker housing A of the enclosed switchboard ES. The actuation lever 8, therefore, pivots upward and downward with one of two upper apex portion thereof, i.e., the upper apex portion 11 as a fulcrum Oi since the upper apex portion 11 is provided with the other horizontal axle 0, whose ends are fixed to both side walls in the circuit breaker housing A of the enclosed switchboard ES.Furthermore, a lower end of each of a pair of rods 12 is pivotally attached to the other upper apex portion 11' of the actuation level 8. The pair of rods 12 moves simultaneously upward and downward according to the pivotal movement of the actuation lever 8.

Each of the pair of rods 12 is movably inserted into two spaced-apart holes 1 3A, 1 3B provided at upper and lower ends of corresponding one of a pair of guide frames 1 3. The pair of guide frames 13 are disposed in parallel with each other along the respective side ends of the grounded partition wall 3 so as to place the above-described pair of upper and lower bushings 2A and 2B therebetween as shown in Figs. 2 and 3(A).In addition, the shuttering apparatus 7 includes a pair of upper and lower supporting arms 14A and 1 4B at each side of the pair of guide frames 13, one end of each pair of upper and lower supporting arms 1 4A and 1 4B being pivotally fixed to the corresponding guide frame 1 3 and the other end thereof being fixed to one end of the corresponding shutter plate 1 5A and 1 5B. Therefore, each of the shutter plates 1 SA and 1 SB can pivot upward or downward on each end OA2 and OB2 as a fulcrum of the corresponding supporting arm 1 4A and 1 4B which is located at the guide frame side so as to cover or uncover the front surface 2A' and 2B' of the corresponding upper and lower bushing 2A and 2B which faces the truck-mounted circuit breaker 1.A pair of upper and lower stopper members 1 6A and 1 6B are, furthermore, provided on each of the pair of guide frames 13 for stopping the corresponding supporting arms 1 4A and 1 4B and shutter plate 1 SA and 1 SB fixed thereto at the covering position of each of the front surfaces 2A' and 2B' of the corresponding bushings 2A and 2B as shown in Fig. 3(A). Each pair of upper and lower stopper members 1 6A and 1 6B is, therefore, located somewhat below the lower side of the corresponding bushings 2A and 2B as shown in Fig. 3(A). On the one hand a pair of upper pins 1 7A are extended from substantially central positions of the pair of the upper supporting arms 1 4A. Similarly, a pair of lower pins 1 7B are extended from substantially central portions of the pair of the lower supporting arms 1 4B.On the other hand, a pair of inversed C-shaped upper guide arms 1 8A are extended toward the grounded partition wall 3 from the pair of rods 12, with both ends of each thereof fixed to the corresponding rod 12, for guidably actuating the upper pins 1 6A projected from the pair of upper supporting arms 1 4A.

Similarly, a pair of inversed C-shaped lower guide arms 1 8B are extended toward the grounded partition wall 3 from the pair or rods 12, with both ends of each thereof fixed to the corresponding rod 12, for guidably actuating the lower pins 1 6B projected from the pair of lower supporting arms 1 4B. Therefore, the upper and lower supporting arms 1 4A and 1 4B and associated shutter plates 1 SA and 1 SB are pivoted upward and downward when the pair or rods 12 move upward and downward so that the inversed C-shaped guide arms 1 8A and 1 8B actuate the engaged upper and lower pins 1 7A and 1 7B extended from the respective supporting arms 1 4A and 1 4B to come into contact with both upper and lower edges of the respective inversed C-shaped 'guide arms 1 8A and 1 8B as appreciated from Fig. 3(A).

Furthermore, a pair of upper and lower metal fixtures 1 9A and 1 9B are pivotally attached to one of the guide frames 13 so as to operatively engage with each of the corresponding supporting arms 1 4A and 1 4B at respective predetermined points between the upper and lower limits of the stroke of the corresponding supporting arm 1 4A and 148. Each of the upper and lower metal fixtures 1 9A and 1 9B is of a substantially rectangular shape partially cut away.

Each of the upper and lower metal fixtures 1 9A and 1 9B has a fulcrum OA3 and OB3 deviated from a center of gravity toward the side of the corresponding supporting arm 1 4A and 14B, a bent portion 1 9Ab and 1 9Bb at one side end thereof with the fulcrum OA3 and OB3 as a center for serving as a knob, and a cut-out portion 1 9Aa and 1 9Ba at the other side end thereof for receiving the side edge of the corresponding supporting arm 1 4A and 1 4B. Each of a pair of stopper pins 20A and 20B is extended adjacent to the corresponding metal fixture 1 9A and 1 9B from one of the pair of the guide frames 13 for stopping the pivotal movement of the corresponding metal fixture 1 9A and 1 9B due to the weight difference between both ends with each fulcrum OA3 and OB3 as a center.Each of the upper and lower metal fixtures 1 9A and 1 9B is, therefore, suspended substantially vertically on the guide frame 13 by means of the corresponding stopper pin 20A and 20B and fulcrum OA3a and OB3 thereof so as not to engage with the side edge of the corresponding supporting arm 1 4A and 1 4B. At this time, both of the shutter plates 1 5A and 1 SB can cover or uncover the front surfaces 2A' and 2B' of the pair of upper and lower bushings 2A and 2B regardless of the metal fixtures 1 9A and 1 9B.

On the other hand, when an operator carries the truck-mounted circuit breaker 1 out of the circuit breaker housing A of the enclosed switchboard ES for, e.g., maintenance and both of the upper and lower shutter plates 1 SA and 1 SB are operated to cover the front surfaces 2A' and 2B' of the pair of upper and lower bushings 2A and 2B, the operator can forcefully open both of the upper and lower shutter plates 1 5A and 1 SB so as to move upward to check any of the upper and lower bushings 2A and 2B. At this time, if the operator moves the bent portions 1 9Ab and 1 9Bb of the metal fixtures 1 9A and 1 9B to pivot the metal fixtures 1 9A and 19B to engage with the respective side edges of the corresponding supporting arms 1 4A and 14B, each of the upper and lower shutter plates 1 SA and 1 SB can be held in a substantially open state somewhat below a fully opened position. This will be appreciated from Fig. 3(B) in which the lower supporting arm 1 4B depicted in the solid line is held in the substantially open state by means of the lower metal fixture 1 9B.This substantially open position of the respective shutter plates 1 4A and 1 4B is determined by the abovedescribed respective stopper pins 20A and 20B shown in Fig. 2 provided adjacent to the corresponding metal fixtures 1 9A and 1 9B. Thus, each of the stopper pins 20A and 20B also serves to limit the further pivotal movement of the corresponding metal fixture 1 9A and 1 9B when the supporting arms 1 4A and 1 4B engaged with the corresponding metal fixtures 1 9A and 1 9B are pivoted downward in each direction which the corresponding shutter plate 1 4A and 1 4B covers the front surfaces 2A' and 2B' of the bushings 2A and 2B due to the weight of the engaged supporting arm 1 4A and 1 4B and shutter plate 1 5A and 1 SB theirselves.

Next, in the above-described previously proposed shuttering apparatus, the pair of rods 12 are lifted and stopped at a predetermined height while the truck-mounted circuit breaker 1 is housed in the circuit breaker housing A of the enclosed switchboard ES and is in operation. At this time, each of the upper and lower shutter plates 1 SA and 1 SB is pivoted upward through each of the guide arms 1 8A and 1 8B and held at the fully opened position above the corresponding bushings as shown by phantom lines in Fig. 3(B).

On the other hand, the pair of rods 12 are moved downward in response to the downward pivotal movement of the actuating lever 8 when the truck-mounted circuit breaker 1 is carried out of the circuit breaker housing A of the enclosed switchboard ES. At this time, each of the pair of upper and lower supporting arms 1 4A and 1 4B is pivoted downward so that each of the shutter plates 1 5A and 1 5B simultaneously cover the 1 5A and 1 5B front surfaces 2A' and 2B' of the corresponding upper and lower bushings 2A and 2B.

In addition, in a case when the operator wants to check for any of the upper and lower bushings 2A and 2B with the truck-mounted circuit breaker 1 carried out of the circuit breaker housing A of the enclosed switchboard ES, the operator can forcefully lift either or both of the upper and lower shutter plates 1 SA and 1 SB to pivot upward and turns both of the upper and lower metal fixtures 1 9A and 1 9B to place the cut-out portions 1 9Aa and 1 9Ba thereof below the respective side edges of the corresponding supporting arms 1 4A and 1 4B.In this state, the upper and lower shutter plates 1 SA and 1 SB are pivoted downward by the operator to settle the respective side edges of the upper and lower supporting arms 1 4A and 1 4B on the cut-out portions 1 9Aa and 1 9Ba of the corresponding metal fixtures 1 9A and 1 9B.

Consequently, the metal fixtures 1 9A and 1 9B can be engaged with the respective supporting arms 1 4A and 1 4B, the upper and lower shutter plates 1 SA and 1 SB being held in the substantially open state as described hereinabove. It should be noted that as appreciated from Fig. 2 and Fig. 3(B) the lower supporting arm 1 4B is held at the substantially open state by means of the lower metal fixture 1 9B, each of the rods 1 2 is accordingly moved upward to lift the lower pins 1 7B to place it also in the substantially open position and also to lift the upper pins 1 7A so that the upper shutter plate 1 SA (not shown in Fig. 3(B)) is also placed in the substantially open position.When the truckmounted circuit breaker 1 is carried into the circuit breaker housing A of the enclosed switchboard ES after the end of the checking, both of the pair of upper and lower supporting arms 1 4A and 1 4B engaged with the corresponding metal fixtures 1 9A and 1 9B are further pivoted upward by a short distance from the substantially open position as appreciated from Fig. 3(B) by indicating in the solid lines to the fully opened position as appreciated from Fig.

3(B) by indicating in the phantom lines. Therefore, the upper and lower shutter plates 1 SA and 1 SB are operated to cover the respective surfaces 2A' and 2B' of the upper and lower bushings 2A and 2B as is in the same manner of the normal case next when the truck-mounted circuit breaker 1 is carried out of the circuit breaker housing A of the enclosed switchboard ES. Accordingly, one of the upper and lower supporting arms 1 4A and 1 4B is disengaged from the corresponding metal fixture 1 9A and 1 9B so that the metal fixture 1 9A and 1 9B spontaneously returns to the original vertically suspended position.

However, there are drawbacks in the abovedescribed previously proposed shuttering apparatus. That is to say, one of the shutter plates 1 SA and 1 SB, i.e., the lower shutter plate 1 SB shown in Fig. 2 through Fig. 3(B) is pivoted upward and held at an intermediate position as typically shown in Fig. 3(A) and Fig. 3(B) between the pair of upper and lower bushings 2A and 2B, the pair of upper and lower bushings 2A and 2B being disposed at the upper and lower portions of the grounded partition wall 3, when the truckmounted circuit breaker 1 is carried into the circuit breaker housing A of the enclosed switchboard ES.Therefore, a distance between the above-described lower shutter plate 1 SB and upper bushings 2A connected to the power supply bus 4 becomes considerably shorter so that an insulating distance between the upper bushings 2A and lower shutter plate 1 SB becomes accordingly shorter and, therefore, an accident of sparkover between one of the upper bushings 2A and grounded lower shutter plate 1 SB will easily occur. Furthermore, the speed of covering and uncovering operations of the respective shutter plates 1 SA and 1 SB is relatively slow as compared with an average speed at which the truck-mounted circuit breaker 1 is carried into and out of the circuit breaker housing A of the enclosed switchboard ES since these shutter plates 1 SA and 1 SB are pivoted upward and downward on the ends OA2 and OB2 of the supporting arms 1 4A and 1 4B as each fulcrum through the inversed C-shaped guide arms 1 8A and 18B.

Consequently, the stationary or movable electrode conductive connector 1 A or 1 B may accidentally collide with the upper or lower shutter plate 1 SA or 1 SB.

The present invention seeks therefore to provide an improved shuttering apparatus in an enclosed switchboard which can place the shutter plates particularly the lower shutter plate far away from the upper bushings which are connected to the power supply bus via the branch bus while the shuttering plates are fully opened to uncover the respective front surfaces of the pair of upper and lower bushings and can respond quickly when the truck-mounted circuit breaker is carried into and out of the circuit breaker housing of the enclosed switchboard.

According to the present invention, a shuttering apparatus comprises: (a) an actuation lever (8), disposed within the circuit breaker housing and one end thereof being axially secured to both side walls of the enclosed frame of the enclosed switchboard, which, responsive to the movement of the truckmounted circuit breaker, on the axially secured end thereof as a fulcrum pivots upward when the truck-mounted circuit breaker is carried into the circuit breaker housing and pivots downward when the truck-mounted circuit breaker is carried out of the circuit breaker housing; (b) at least one rod (12'), spaced spars from the grounded partition wall, extended vertically in the vicinity of a side of the upper and lower bushings, and a lower end thereof being pivotally attached to the other end of said actuation lever, which, responsive to the pivotal movement of said actuation lever, moves upward as said actuation lever pivots upward and moves downward as said actuation lever pivots downward; (c) upper and lower guide plates (21 A, 21 B), said upper guide plate being located above the upper bushing and said lower guide plate being located below the lower bushing, each of which guidably inserts said rod therethrough; (d) a pair of upper and lower shutter plates (24A, 24B) for covering respective front surfaces of the upper and lower bushings with which are to be connected the stationary and movable electrode conductive connectors extended from the truck-mounted circuit breaker; (e) an upper shutter plate supporting arm (22A) one end thereof being fixed to a side end of said upper shutter plate and the other end thereof being pivotally supported by said upper guide plate (f) a lower shutter plate supporting arm (22by one end thereof being fixed to a side end cf said lower shutter plate and a substantially central portion thereof being axially supported by said lower guide plate; (g) an upper cam plate (27A), one end thereof fixed to said rod and the other end thereof extended toward the truck mounted circuit breaker, which slidably supports said upper shutter plate supporting arm; and (h) a lower cam plate (27B), one end thereof fixed to said rod and the other end thereof extended toward the grounded partition wall opposite to said upper cam plate, which slidably supports said lower shutter plate supporting arm, whereby when the truck-mounted circuit breaker is carried into the circuit breaker housing of the enclosed switchboard, said rod moves upward simultaneously when said actuation lever is pivoted upward and accordingly said upper shutter plate supporting arm is pivoted upward via said upper cam plate so that said upper shutter plate is spaced apart from the upper bushing and, on the other hand, said lower shutter plate supporting arm is pivoted downward via said lower cam plate so that said lower shutter plate is spaced apart from said upper and lower bushings.

One previously proposed shuttering apparatus has been described hereinabove with reference to Figs. 1 through Fig. 3(B) of the accompanying drawings and one specific form of a shuttering apparatus constructed in accordance with the present invention will be described hereinbelow by way of example with reference to Figs. 4 through 7 of the accompanying drawings, in which:: Fig. 1 is an arrangement side view of an enclosed switchboard in which one previously proposed shuttering apparatus is incorporated; Fig. 2 is a partially cut away front view of the previously proposed shuttering apparatus shown in Fig. 1; Fig. 3(A) is a partially cut away side view of the shuttering apparatus shown in Fig. 2 for explaining the operation of the previously proposed shuttering apparatus; Fig. 3(B) is a partially cut away side view of the shuttering apparatus shown in Fig. 2 for particularly explaining the operation of a lower support arm between a substantially open state and fully open state shown in Fig. 3(A); Fig. 4 is an arrangement side view of the enclosed switchboard in which a shuttering apparatus showing one specific embodiment of the present invention is incorporated;; Fig. 5 is a side view of the shuttering apparatus shown in Fig. 4 in which the enclosed switchboard is partially cut away; Fig. 6 is a plane sectional view around an upper shutter plate supporting arm shown in Fig. 5 taken away along the line XX in Fig. 5; and Fig. 7 is a traverse sectional view around a lower shutter plate supporting arm shown in Fig.

5 taken away along the line Y-Y in Fig. 5; Reference will be made hereinafter with reference to Fig. 4 through 7 in order to facilitate understanding of the present invention.

Figs. 4 through 7 show one specific embodiment of the shuttering apparatus incorporated in the enclosed switchboard according to the present invention.

First, as shown in Fig. 4 and Fig. 5, upper and lower guide plates 21 A and 21 B are extended vertically from the grounded partition wall 3. As appreciated from Fig. 5, the upper guide plate 21 A is disposed slightly above the upper bushings 2A aligned horizontally while the lower guide plate 21 B is disposed slightly below the lower bushings 2B also aligned horizontally. Such upper and lower guide plates 21 A and 21 B may preferably be attached adjacent to both left and right sides of the pair of upper and lower bushings 2A and 2B as viewed from the circuit breaker housing A.In the case of a three-phase power supply bus 4 as indicated by Fig. 4, such upper and lower guide plates 21 A and 21 B are attached adjacent to both left side of each of the leftmost upper and lower bushings 2A and 2B and right side of each of the rightmost upper and lower bushings 2A and 2B as viewed from the circuit breaker housing A. A substantially hornshaped upper shutter plate supporting arm 22A is pivotally supported by an upper axle 23A fixed to the upper guide plate 21 A as typically shown in Fig. 6. The upper shutter plate supporting arm 22A is fixed to a side end of an upper shutter plate 24A at one end thereof. An upper pin 25A is projected from a substantially central portion of the upper shutter plate supporting arm 22A.

Another substantially horn-shaped lower shutter plate supporting arm 22B which is somewhat longer than the upper shutter plate supporting arm 22A has a lower pin 25B at one end thereof.

The other end of the lower shutter plate supporting arm 22B is fixed to a side end of a lower shutter plate 24B. It should be noted that a lower axle 23B is projected from a substantially central position between both ends of the lower shutter plate supporting arm 22B. It should also be noted that as appreciated from Fig. 5 a distance between each end of the upper or lower shutter plate supporting arm 22A or 22B which is fixed to the corresponding shutter plate 24A or 24B and corresponding upper or lower axle 23A or 23B is longer than that between each of the upper and lower shafts 23A and 23B and corresponding upper or lower pin 25A or 25B.

On the other hand, two guide pieces 26A and 26B each having a hole 26A' and 26B' as shown in Fig. 6 and Fig. 7 are extended vertically from the left top ends of the upper and lower guide plates 21 A and 21 B. One of two rods 12' is passed through each hole 26A', 26B' of the guide pieces 26A and 26B in the case when each of the upper and lower guide plates 21 A and 21 B constitutes a pair.As appreciated from Figs. 5 through 7, upper and lower cam plates 27A, 278 are fixed to the rod 12', respectively, in the vicinity of the upper and lower shutter plate supporting arms 22A, 22B. The upper cam plate 27A is extended toward the track-mounted circuit breaker 1 (not shown in detail in Fig. 5) with the rod 12' as a centre whereas the lower cam plate 27B is projected toward the grounded partition wall 3 with the rod 12' as a center. A lower end of the rod 12' is pivotally attached to one upper apex 11' of the actuation lever 8.Since the construction of the actuation lever 8 is the same in the previously proposed shuttering apparatus described hereinbefore with reference to Figs. 1 through 3(8), the explanation of the actuation lever 8 is omitted here.

It should be noted that since the lower shutter plate supporting arm 218 has the lower pin 25B at the end thereof opposite to the end fixed to the lower shutter plate 24B, the lower pin 258 being slidably engaged with the lower cam plate 27B, and the part of the lower shutter plate supporting arm 22B which is at the side of the lower shutter plate 24B with the lower axle 23B as a center is unbalanced in weight due to a short distance between the lower pin 25B and lower axle 23B, the lower shutter plate 24B cannot cover the front surfaces 2B' of the lower bushings 2B quickly under such conditions. Therefore, as seen in Fig.

7, a spring 28 is wound on the lower axle 238 intervened between the lower guide plate 218 and lower shutter plate supporting arm 22B. One end of the spring 28 is fixed to the lower guide plate 21 B and the other end thereof is fixed to the lower shutter plate supporting arm 22B so that the lower shutter plate supporting arm 228 is always biased to pivot upward quickly against the weights thereof and the lower shutter plate 24B itself in response to the upward movement of the rod 12' so as to cover the front surfaces 2B' of the lower bushings 2B.

Next, the operation of the shuttering apparatus 7 of the specific embodiment according to the present invention will be described hereinafter.

As shown in solid lines of Fig. 5, when the truck-mounted circuit breaker 1 is carried out of the circuit breaker housing A of the enclosed switchboard ES, the actuation lever 8 is pivoted downward on the second axle 0, due to the weights of the upper and lower shutter plate supporting arms 22A and 228, upper and lower shutter plates 24A and 248, and two rods 12' with the roller 10 thereof being in a floating state.

At this time, the upper and lower shutter plates 24A and 24B are fully closed to cover the upper and lower bushings 2A and 2B, respectively, so as to prevent an operator or any other person entering the circuit breaker housing A from contacting accidentally either of the front surfaces 2A' and 2B' of the upper and lower bushings 2A and 2B.

On the other hand, when the truck-mounted vircuit breaker 1 is carried into the circuit breaker housing A of the enclosed switchboard ES, the roller 10 which has been projected so as to interrupt the movement of the truck 1 C is brought in contact with the oblique edge 1 b of the truck 1 C, rolls onto the oblique edge 1 b and the upper surface 1a of the truck 1 C as the truck 1C enters the circuit breaker housing A. In this way, the change in height of the roller 10 causes the actuation lever8 to pivot upward on the second axle 0, so as to move the rod 12' upward. As the rod 12' shown in Fig. 5 is moved upward, the upper and lower cam plates 27A, 27B fixed to the rod 12' move upward the upper and lower pins 25A and 25B slidably engaged therewith along their respective elongated holes 29 with their corresponding upper and lower axles 23A and 23B as their respective centers. Therefore, the upper shutter plate supporting arm 22A pivots upward on the upper axle 23A so that the upper shutter plate 24A is separated far away from the upper bushings 2A and simultaneously the lower shutter plate supporting arm 228 pivots downward on the lower axle 23B so that the lower shutter plate 24B is separated far away from the upper and lower bushings 2A and 2B (as shown in phantom lines of Fig. 5).After the upper and lower shutter plates 24A, 24B have been pivoted completely upward and downward, respectively, the stationary and movable electrode conductive connectors 1 A and 1 B extended from the truck-mounted circuit breaker 1 are connected completely to the power supply bus 4. As shown in Fig. 4, when the truckmounted circuit breaker 1 is housed in the circuit breaker housing A of the enclosed switchboard ES, the roller 10 of the actuation lever 8 is positioned stably on the upper surface of the truck 1 C. Therefore, the actuation lever 8 does not move, with the upper and lower shutter plates 24A and 24B being held at the upward and downward extremes, i.e., their respective fully opened positions.

Next, when the truck-mounted vacuum circuit breaker 1 is carried out of the circuit breaker housing A of the enclosed switchboard ES, the actuation lever 8 is pivoted downward on the second axle O since the roller 10 of the actuation lever 8 rolls on the upper surface 1 a of the truck 1 C and thereafter drops off the oblique edge 1 b of the truck 1. When the actuation lever 8 is pivoted downward on the second axle 01, the rod 12' pivotally attached to the other apex 11' is moved downward. Accordingly, the upper shutter plate supporting arm 22A is pivoted counterclockwise so that the upper shutter plate 24A is fully closed to cover the front surfaces 2A' of the upper bushings 2A.At this time, the counterclockwise pivotal movement of the upper shutter plate supporting arm 22A is quicker than the previously proposed supporting arm 1 4A shown in Fig. 3(A) because of the addition of weights of both upper shutter plate 24A and shutter plate supporting arm 22A. Therefore, the front surfaces 2A' of the upper bushings 2A are quickly covered. On the other hand, the lower shutter plate supporting arm 23A is pivoted clockwise so that the lower shutter plate 24B is fully closed to cover the front surfaces 2B' of the lower bushings 28.At this time, although the clockwise pivotal movement of the lower shutter pla.te supporting arm 22B needs to overcome the weights of the lower shutter plate 24B and lower shutter plate supporting arm 22B, the biasing force of the above-described spring 28 permits the lower shutter plate 24B to quickly cover the front surfaces 2B' of the lower bushings 2B similarly in the case of the upper shutter plate 24A.

As described hereinabove, small strokes of at least one rod 12' permit large radial and quick pivotal movements of the upper and lower shutter plate supporting arms 22A and 22B due to the principle of lever in cooperation with the carriage operation of the truck-mounted circuit breaker 1 into or out of the circuit breaker housing A of the enclosed switchboard ES. Therefore, since according to the present invention the lower and upper shutter plates 24A and 248 are actuated to separate far away from the corresponding upper and lower bushings 2A, 28 toward opposing directions with each other in such a way that one of the grounded shutter plates, i.e., the lower shutter plate 24B is not placed at the intermediate position between the upper and lower bushings 2A and 2B.Consequently, the shuttering apparatus 7 according to the present invention can assure more safe maintenance operation and checking within the enclosed switchboard ES.

On the other hand, an electric insulation can be improved since the grounded upper and lower shutter plates 24A and 248 move toward opposite directions to each other and take longer spatial distance between the upper bushings 2A and the lower shutter plate.

Furthermore, since physical moments can be increased due to longer distances between the upper and lower axles 23A and 238 and upper and lower pins 25A and 25B at the upper and lower shutter plate supporting arms 22A and 22B, respectively, the upper and lower shutter plates 24A and 24B upward and downward more easily and more quickly even though the upper and lower shutter plates 24A and 24B have large dimensions.

Claims

1. A shuttering apparatus in an enclosed switchboard, the enclosed switchboard having a grounded partition wall within an enclosed frame of the enclosed switchboard which partitions a circuit breaker housing in which a truck-mounted circuit breaker is housed and a bus housing in which a power supply bus and load cable bus are housed and at least one pair of upper and lower bushings disposed with space apart from each other at the upper and lower portions of the grounded partition wall, the upper bushing being provided for connecting a stationary electrode conductive connector extended from the truckmounted circuit breaker with the power supply bus and the lower bushing being provided for connecting a movable electrode conductive connector extended therefrom with the load cable bus, said shuttering apparatus comprising:: (a) an actuation lever (8), disposed within the circuit breaker housing and one end thereof being axially secured to both side walls of the enclosed frame of the enclosed switchboard, which, responsive to the movement of the truckmounted circuit breaker. on the axially secured end thereof as a fulcrum pivots upward when the truck-mounted circuit breaker is carried into the circuit breaker housing and pivots downward when the truck-mounted circuit breaker is carried out of the circuit breaker housing;; (b) at least one rod (12'), spaced apart from the grounded partition wall, extended vertically in the vicinity of a side of the upper and lower bushings, and a lower end thereof being pivotally attached to the other end of said actuation lever, which, responsive to the pivotal movement of said actuation lever, moves upward as said actuation lever pivots upward and moves downward as said actuation lever pivots downward; (c) upper and lower guide plates (21 A, 21 8), said upper guide plate being located above the upper bushing and said lower guide plate being located below the lower bushing, each of which guidably inserts said rod therethrough;; (d) A pair of upper and lower shutter plates (24A, 248) for covering front surfaces of the upper and lower bushings with which are to be connected the stationary and movable electrode conductive connectors extended from the truckmounted circuit breaker; (e) an upper shutter plate supporting arm (22A) one end thereof being fixed to a side end of said upper shutter plate and the other end thereof being pivotally supported by said upper guide plate; (f) a lower shutter plate supporting arm (22B) one end thereof being fixed to a side end of said lower shutter plate and a substantially central portion thereof being axially supported by said lower guide plate; (g) an upper cam plate (27A), one end thereof fixed to said rod and the other end thereof extended toward the truck-mounted circuit breaker, which slidably supports said upper shutter plate supporting arm; and (h) a lower cam plate (27B), one end thereof fixed to said rod and the other end thereof extended toward the grounded partition wall opposite to said upper cam plate, which slidably supports said lower shutter plate supporting arm whereby when the truck-mounted circuit breaker is carried into the circuit breaker housing of the enclosed switchboard, said rod moves upward simultaneously when said actuation lever is pivoted upward and accordingly said upper shutter plate supporting arm is pivoted upward via said upper cam plate so that said upper shutter plate is spaced apart from the upper bushing and, on the other hand, said lower shutter plate supporting arm is pivoted downward via said lower cam plate so that said lower shutter plate is spaced apart from said upper and lower bushings.

2. The shuttering apparatus as set forth in claim 1, the shuttering apparatus further comprising a pin (23B) extended from a substantially central portion of said lower shutter plate supporting arm which is pivotally supported by said lower guide plate and elastic means (28) wound on said pin which biases so that said lower shutter plate supporting arm is pivoted upward on said pin to cover the front surface of the lower bushing in response to the downward movement of said rod against the weights of said lower shutter plate and lower shutter plate supporting arm.

3. A shuttering apparatus in an enclosed switchboard in which a truck-mounted circuit breaker is housed, substantially as described hereinbefore with reference to and as illustrated in Figures 4 to 7 of the accompanying drawings.

4. Any other novel feature or combination disclosed hereinbefore or shown in the accompariying drawings.