JPH1146411A - Interlock device for metal enclosed switchboard - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an inspection cover attached to a transmission conductor arranging chamber mechanically lockable and unlockable in accordance with the earthing state of a transmission conductor. SOLUTION: A locking bar 80 is arranged in a state where the bar 80 is swung in the forward-backward direction between a back lid 12 which is attached to a transmission chamber 3 as an inspection cover and an earthing switch 6. The base end of the bar 80 is coupled with an oscillating lever 65 through a coupling link 81 so that the bar 8 may be pushed and pulled through the link 81 in accordance with the oscillation of the lever 65. When the switch 6 is in a non-earthing state, the front end of the bar 80 pushed by the link 81 comes into contact with part of the lid 12, and restricts the lid 12 in a closed state by inhibiting the upward movement of the lid 12 which is required prior to the opening of the lid 12. When the switch 6 is set to an earthing state, on the other hand, the bar 80 is pulled backward by the oscillation of the lever 65 and separated from the lid 12. Therefore, the bar 80 does not inhibit the upward movement of the lid 12 and the lid 12 becomes openable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an inspection cover for covering a cable room provided with a load-side conductor in a closed switchboard.
The present invention relates to an interlock device that locks a load-side conductor depending on whether or not a load-side conductor is grounded by a grounding switch.

[0002]

2. Description of the Related Art In a closed switchboard, a plurality of compartments are formed by partitioning the inside of an outer box constituted as a box made of a grounded metal from each other by a partition made of a grounded metal or an insulating material, and forming a plurality of compartments. , A bus-side branch conductor connected to a common bus, a load-side conductor connected to a power transmission cable for transmitting power to loads such as other electric rooms and load equipment, a switchgear that connects and separates both conductors, and monitoring control. The configuration accommodates internal devices such as necessary control devices.

In such a closed switchboard, each of the compartments is covered with an inspection cover so as to be openable and closable from the outside, and the inspection cover is opened so that the internal equipment of each compartment can be individually inspected.
At the time of this inspection, the target equipment is grounded before opening the inspection cover in order to prevent an electric shock accident of the inspection worker due to the residual voltage of the internal equipment.
In a compartment (cable room) provided with a load-side conductor in which a high voltage may remain, an interlock device that prohibits opening of an inspection cover until grounding is often provided.

[0004] As this kind of interlock device, a device disclosed in Japanese Patent Application Laid-Open No. 55-18805 is conventionally known. This means that the output rod of the electromagnetic cylinder fixed to the outer box is engaged with a part of the inspection cover to perform a locking action that prohibits the inspection cover from being opened, and on the other hand, on condition that an operation for grounding is performed. In this configuration, the cylinder is excited to release the engagement with the inspection cover, and the inspection cover can be opened.

[0005]

However, in the above-mentioned conventional interlock device, in order to excite and demagnetize the electromagnetic cylinder, a detecting means for detecting the presence or absence of a grounding operation, and a detection of the open / closed state of the inspection cover. Means and a control circuit for performing the excitation and demagnetization in accordance with the results of these detections are required, resulting in a problem that the configuration becomes complicated.

Further, if an abnormality occurs in the detection means or the control circuit, locking or unlocking may not be possible. In particular, when the locked state cannot be obtained, the inspection is performed without grounding. The cover was accidentally opened,
There is a possibility that the above-mentioned electric shock accident may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and enables an inspection cover for opening and closing a cable room provided with a load-side conductor to be mechanically locked and unlocked according to the presence or absence of grounding. It is an object of the present invention to provide an interlock device capable of reliably preventing the inspection cover from being opened in a state where the grounding is not performed.

[0008]

An interlock device for a closed switchboard according to the present invention is mechanically linked to a movable portion of a grounding switch provided for grounding a load-side conductor.
A lock means is provided to allow the inspection cover of the cable room to be opened during grounding, and to lock the inspection cover in a closed state when the grounding is released.

In the present invention, when the load-side conductor is grounded by the operation of the grounding switch, the operation of the locking means mechanically connected to the movable portion of the grounding switch causes
When the inspection cover of the cable chamber can be opened and the ground release operation is performed, the inspection cover is restrained in the closed state by the operation of the locking means.

According to a second aspect of the present invention, there is provided an interlock device for a closed switchboard, wherein an inspection cover which can be opened by releasing the engagement with an outer box by moving in one direction in a mounting surface, and a grounding switch. And a lock bar which is pushed and pulled through the connecting link to abut a part of the inspection cover by the operation of the movable portion, and restrains the movement of the inspection cover.

According to the present invention, the contact portion for bringing the tip of the lock rod into contact with the inspection cover which can be opened by moving in one direction in the mounting surface to disengage the engagement portion is provided. When the lock rod is pushed through the connecting link in accordance with the operation of the movable part of the grounding switch, the tip of the lock rod comes into contact with the contact part, and the inspection cover for releasing the engagement is provided. When the lock rod is pulled, the contact of the tip of the lock rod with the contact part is released, allowing the inspection cover to move and opening the inspection cover. .

An interlock device for a closed switchboard according to a third aspect of the present invention utilizes a reinforcing rib provided on an inner surface of an inspection cover as a member for abutting on a lock rod.

According to the present invention, a reinforcing rib provided on the inner surface of the inspection cover is used without providing a dedicated part as a contact portion for contacting the lock rod.

According to a fourth aspect of the present invention, there is provided an interlock device for a closed switchboard, wherein a connecting link of a lock rod is connected to a connecting portion of an operating link of a grounding switch.

According to the present invention, in order to connect the connecting link for transmitting the operation of the movable portion of the grounding switch to the lock rod, the operation link of the operation link originally required for the grounding operation and the grounding release operation of the grounding switch is provided. The use of a connecting part eliminates the need to add a dedicated part.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a side sectional view showing a schematic configuration of a closed switchboard provided with an interlock device according to the present invention, FIG. 2 is a front view thereof, and FIG. 3 is a rear view thereof.

In this closed switchboard, the inside of an outer box 1 made of a grounded metal having a rectangular box shape is partitioned by a partition made of a grounded metal or an insulating material, and a busbar chamber 2 in which a busbar side branch conductor 20 is disposed.
And a cable room 3 in which the load-side conductor 30 is disposed, a circuit breaker room 4 in which a circuit breaker 40 as a switchgear is stored, and a control device room 5 in which a control device (not shown) is stored. It has a configuration.

A circuit breaker room 4 is formed in the lower part of the front half of the outer box 1 (the left part of FIG. 1), and a control equipment room 5 is formed in the upper part thereof. As shown in 2,
Each of the outer boxes is openably and closably covered by another front door 10, 11 whose one edge is hinged to a side edge of the outer box. The front door 10 covering the front of the circuit breaker room 4 is screwed on the side edge opposite to the hinged side with a plurality of fixing bolts 10a, 10a,. It is designed not to open due to an increase in internal pressure.

The rear half of the circuit breaker room 4 is extended in the height direction along the rear side of the control device room 5, and the upper part thereof is connected to the top plate of the outer box 1. , Breaker room 4
When an internal accident occurs, it is used as an air path for releasing the rise in internal pressure caused by the internal accident, and as a radiating air path for the circuit breaker 40 during normal use. The circuit breaker 40 is mounted on a trolley 41 that can move back and forth along the floor of the circuit breaker room 4 and can be pulled out together with the trolley 41 in front of the outer box 1 with the front door 10 opened. ing. On the rear wall of the circuit breaker room 4, disconnecting portions 42 and 43 of the main circuit are fixed at predetermined intervals in the vertical direction with a connection opening facing forward.
Is connected to the circuit breaker chamber 4 together with the truck 41, and connects the connection terminals 44, 44 (only one of which is shown) projecting from the rear surface to the disconnecting portion.
The disconnection portions 42 and 43 are electrically connected or cut off by opening and closing a contact (not shown) incorporated in the mounted state.

The busbar chamber 2 is formed on the rear side of the circuit breaker chamber 4 and includes a projecting position of the disconnecting portion 42 at a lower portion thereof.
In the upper part of the bus chamber 2, three bus-side branch conductors 20, 20, 20 connected to three-phase buses (not shown) are respectively provided with insulators 21, 20.
The lower portions of the bus-bar-side branch conductors 20, 20, 20 are connected to the disconnecting section 42. FIG. 1 shows single disconnecting portions 42 and 43, respectively, which are juxtaposed in the thickness direction of the drawing so as to correspond to each of the three phases. 20,
Reference numerals 20, 20 are connected to corresponding disconnecting portions 42, 42, 42, respectively.

The cable room 3 is formed at the rear side of the bus room 2 over substantially the entire height of the outer box 1, and its lower portion is extended forward by being separated by the lower wall of the bus room 2. The disconnecting portion 43 faces a rearward position of the container room 4. A power transmission cable C is drawn into the cable chamber 3 from the bottom surface of the outer box 1. The power transmission cable C is a load-side conductor 30 insulated and supported by insulators 31 and 32.
It is connected to the.

The load-side conductor 30 is connected to disconnecting portions 42 and 43.
Similarly to the above, the three phases are arranged side by side in the thickness direction of the paper surface, and these are connected to the disconnecting portions 43 corresponding to the three phases. In the middle of the load-side conductor 30, insulators 31, 32
The breaker is inserted through a transformer 33 disposed therebetween.
The current transmitted to the load-side conductor 30 is transformed by the transformer 33 in response to the input of the switch 40, and is transmitted to the control equipment inside the control equipment room 5.

Now, the disconnecting portion into the cable room 3
A ground conductor 34 is connected to the projecting portion 43 in such a manner as to project rearward and downward together with the load-side conductor 30, and a lower portion of the cable chamber 3 faces the lower end of the rear end of the ground conductor 34. A grounding switch 6 is attached. The grounding switch 6 is, as shown in the figure, on a base 60 fixed to the bottom surface of the outer box 1 in a grounded state, a conductor 62 insulated and supported by an insulator 61, and elastically contacts the grounding conductor 34 from below. A contact 63 swinging around a support shaft erected in the left-right direction, and by operating an operation link mechanism described below from a front position of the circuit breaker chamber 4,
The contact 63 is erected as shown by a broken line in the figure,
By contacting the tip with the conductor 62, the ground conductor 34 and the load-side conductor 30 are grounded.

As described above, the rear side of the cable chamber 3 in which the load-side conductor 30 is disposed is covered by a pair of upper and lower back lids 12 and 13 which are detachably mounted on the back of the outer box 1. Inspection of the internal equipment of the cable room 3 including the side conductor 30 is performed by removing the back lids 12 and 13 as an inspection cover.
The opening of the rear side is made possible.

FIG. 4 is an enlarged sectional view of a main part showing a mounting structure of the back lids 12, 13. As shown in FIG. In the figure, reference numeral 14 denotes a support frame erected along the rear edge of the bottom plate 1a of the outer box 1;
The supporting frame is suspended between the side walls of the outer box 1 at a position corresponding to the interface between the upper edge of the upper case and the lower edge of the upper back cover 13. On the upper surface of the support frame 14, an engagement pin 16 is provided to stand substantially vertically with the tip facing upward, and on the rear surface of the support frame 15, an engagement pin 17 having a large-diameter head 17a is provided. It projects substantially horizontally with 17a facing backward.

On the other hand, reinforcing ribs 12a, 13a having an L-shaped cross section are provided on the inner surfaces of the back lids 12, 13 over substantially the entire width along the vicinity of the lower edges thereof. An engagement hole through which the engagement pin 16 can be inserted is formed in the reinforcing rib 12a of the lower back cover 12.
As shown in the figure, the lower portion of the back cover 12 is inserted through the engagement hole 12b into the engagement pin 16 to engage therewith, and the reinforcing rib 12a is placed on the upper surface of the support frame 14. Supported in state. Thus, such an engagement state of the lower portion of the back cover 12 is released by lifting the back cover 12 and extracting the engagement hole 12b above the engagement pin 16.

In the vicinity of the upper edge of the back cover 12, the engaging pin
An engaging hole 18 through which the 17 can be inserted is formed, and the upper portion of the back cover 12 is supported by being prevented from falling off by inserting the engaging hole 18 into the engaging pin 17. FIG. 5 is a view taken along the line V-V in FIG. 4. As shown in FIG. 5, the engagement hole 18 is located above the circular hole 18 a having a diameter through which the head 17 a of the engagement pin 17 can be inserted. A so-called Dharma hole, which is formed by continuously connecting small holes 18b through which the head 17a cannot be inserted, is a so-called Dharma hole.
After the circular hole 18a is inserted through the engaging pin 17, the back cover 12 is shifted downward, and the elongated hole 18b is inserted into the engaging pin 17 as shown in the figure.
Is engaged by passing through the base. And the back cover
Such an engagement state at the upper part of the upper part 12 is released by lifting the back cover 12 and pulling out the rear part with the corresponding position of the circular hole 18a aligned with the axis of the engagement pin 17. In order to remove the back cover 12 in this manner, it is necessary to lift the back cover 12 to move it, to release the engagement between the upper and lower portions, and then to pull out the back.

On the other hand, the lower portion of the upper back cover 13 is supported with the reinforcing ribs 13a mounted on the upper surface of the support frame 15. The lower edge of the back cover 13 extending downward from this support portion overlaps the inside of the upper edge of the lower back cover 12 on the rear surface of the support frame 15, and further, as in the back cover 12, An engagement hole 18 for inserting the engagement pin 17 is formed. As a result, the back cover 13 is restrained so that it cannot be pulled out rearward and lifted upward when the lower back cover 12 is attached. The upper portion of the back cover 13 is supported by the upper edge of the outer box 1 as shown in FIG. 1 by engaging with an engagement pin 17 similar to the upper portion of the lower back cover 12. The cover 13 can be removed by removing the back cover 12 by lifting it upward and pulling it back.

As shown in FIG. 3, the back lids 12, 13 attached in this manner have a plurality of fixing bolts 12c, 12c. And 13
c, 13c... are screwed to the side edges of the outer box 1 to prevent opening when the internal pressure rises due to an internal accident. Also back cover
A pair of handles 12d, 12d on both sides in the width direction
And 13d, 13d are provided, and the back cover 1 is operated as described above.
The removal of 2, 13 and the attachment performed in the reverse procedure can be performed by grasping the handles 12d, 12d and 13d, 13d.

The reinforcing ribs 12a on the inner surface of the back cover 12 are shown in FIG.
As shown in FIG. 6, which is a cross-sectional view taken along the line VI-VI in FIG. 4, each of the bridges is spanned over substantially the entire width thereof. Section frame 1b,
1b, and the back cover 12
Can be used as positioning means in the width direction. Similar reinforcing ribs 12a are provided at a plurality of positions in the height direction of the back cover 12, and the reinforcing ribs 13a on the inner surface of the back cover 13 are also used.

A back cover 12 as an inspection cover for the cable room 3
The back cover 13 is locked or unlocked by an interlock device 8 configured as described below in accordance with the operation of the grounding switch 6 inside the cable room 3. FIGS. 7 and 8 are side views showing the configuration of the interlock device 8 according to the present invention together with the operation mechanism of the ground switch 6. The operation mechanism of the grounding switch 6 and the main part of the interlock device 8 are also shown by a line drawing in FIG.

As described above, the earthing switch 6 swings the contact 63 on the base 60, and the conductor 62 having its tip disposed upward.
, The ground conductor 34 and the load-side conductor 30
The operation of grounding is performed. The base end of the contact 63 is pivotally supported by a substantially horizontal support shaft 64 extending in the width direction of the outer box 1 so as to be swingable with respect to the base 60.
A base end of a swing lever 65 is fixed to the end of the support shaft 64 protruding laterally at a substantially same inclination angle as the contact 63. One end of an operation link 66 is pivotally supported at the tip of the swing lever 65, and the other end of the operation link 66 extending forward is connected to the support shaft at the front position of the outer box 1. 64
And an operation lever 68 pivotally supported by a substantially horizontal support shaft 67.

The operating lever 68 is formed with a recess 68a having an opening at the end thereof. The operating lever 68 is opened by the front side of the outer box 1, more specifically, by the front door 10. As shown by a two-dot chain line in FIG. 7, an operating rod 69 for shutoff operation is inserted into the recess 68a from the front position of the circuit breaker chamber 4 and the swing operation can be performed via the operating rod 69. It has been done.

FIG. 7 shows a state before the operation. At this time, the operation lever 68 is inclined so that the formation side end of the recess 68a faces obliquely forward so that the operation rod 69 can be easily inserted. In the state, the swing lever 65 and the contact 63 connected to the operation lever 68 via the operation link 66 are
The tip of the contact 63 is in a state of being inclined with the tip facing obliquely rearward, the tip of the contact 63 is located at a position away from the upper conductor 62, and the ground switch 6 is in a non-ground state.

In this state, when the operating rod 69 is inserted into the recess 68a and its tip is operated downward, the operating lever 68 swings counterclockwise as shown by the arrow in the figure. The swing is transmitted to the swing lever 65 via the operation link 66, and the swing lever 65 swings counterclockwise together with the support shaft 64, and the swing causes the contact 63 to move as shown in FIG. The contact 63 comes upright on the base 60,
Is pressed against the upper conductor 62, and the ground conductor 34 and the load-side conductor 30 are grounded via the conductor 62. The operation of the earthing switch 6 as described above is effective only when the circuit breaker 40 is pulled out from the inside of the circuit breaker room 4.

In the interlock device 8 according to the present invention, when the grounding switch 6 is in the non-grounding state, the back lids 12 and 13 as the inspection cover of the cable room 3 are restrained in the closed state, and the operation described above is performed. Only when the grounding switch 6 is in the grounding state, the restraint is released, and the operation of allowing the opening of the cable chamber 3 by removing the back covers 12 and 13 is performed. On the side, a lock rod 80 and a connection link 81 are arranged.

The lock rod 80 is slidably supported in the front-rear direction in a plane substantially parallel to the bottom plate 1a of the outer box 1 by a support bracket 82 fixed to a part of the outer box 1. The rear end (the right end in the figure) is extended to a position slightly above a reinforcing rib 12a fixed to the inner surface of the back cover 12. The front end (the left end in the figure) of the lock rod 80 extends to the vicinity of the grounding switch 6. On the other hand, one end of the connecting link 81 is pivotally supported by the tip of the swing lever 65 of the ground switch 6 together with the operation link 66, and the other end is also pivotally supported by the front end of the lock rod 80.

In the interlock device 8 configured as described above, the lock rod 80 is a swing lever of the ground switch 6.
In response to the swing of 65, it is pushed and pulled via the connecting link 81, and accordingly, it slides in the front-rear direction. As shown in FIG. 7, when the grounding switch 6 is in a non-grounding state, the swing lever 65 is in a state where the tip is inclined rearward and upward, and at this time, the lock rod 80 is connected via the connection link 81. It is pushed backward, and its rear end is located slightly above the reinforcing rib 12a on the inner surface of the back cover 12, as described above.

As described above, when the back cover 12 is opened, it is necessary to lift the back cover 12 once and release the engagement with the engagement pins 16 and 17. When in the position shown, the reinforcing ribs 1
As a result of the upper surface of 2a abutting on the lock rod 80 to prevent further lifting, the engagement is not released, and the back cover 12 is restrained in the closed state. Also, as described above, the removal of the upper back cover 13 requires the removal of the lower back cover 12, and the back cover 13 is also restrained in a closed state. In this way, when the ground switch 6 is in the non-ground state, the back lids 12, 13 are securely locked in the closed state.

On the other hand, when the grounding switch 6 is brought into the grounding state as shown in FIG.
65 swings to a position where the tip is tilted forward and upward, and this swing causes the lock rod 80 to be pulled forward through the connecting link 81, and the rear end thereof is a reinforcing rib on the inner surface of the back cover 12. 1
Detach from the upper surface of 2a.

In such a state, the back cover 12 can be pulled upward without being blocked by the lock rod 80, and by this pulling, the engagement with the engaging pins 16 and 17 is released. After that, it can be removed from the outer box 1 by pulling it backward. Further, by this removal, the upper back cover 13 can also be removed, and the cable room 3 can be opened to inspect the inside.
At this time, since the grounding switch 6 is in the grounding state, the internal equipment of the cable room 3 including the load-side conductor 30 is in a state of no voltage, and the inspection work can be performed safely.

As described above, in the present invention, the lock rod 80
With the interlock device 8 having a simple structure including the link member 81 and the connecting member 81, the back lids 12 and 13 as the inspection cover of the cable chamber 3 can be reliably interlocked. The operation of the interlock device 8 is performed by mechanical connection with the movable portion of the grounding switch 6, so that the locking and unlocking based on the detection result of the internal state of the cable chamber 3 is erroneously performed as in the conventional configuration. Back cover 1
Opening of 2, 13 can be reliably prevented.

The configuration of the interlock device 8 is not limited to the configuration described in the above embodiment, and any other configuration may be employed as long as it is mechanically linked to the movable portion of the grounding switch 6. can do.

For example, instead of the lock rod 8, a latch that swings around a horizontal axis is provided near the inner surface of the back cover 12, and the latch and the swing lever 65 of the grounding switch 6 are connected by a link 81.
The latch is rocked according to the rocking of the rocking lever 65, and is engaged with an engaging portion provided on the back surface of the back cover 12, thereby preventing the back cover 12 from being opened. May be. In the above embodiment, the connection link
Although the swing lever 65 as a connecting portion of the operation link 66 is commonly used as a connecting portion between the 81 and the grounding switch 6, a dedicated connecting portion may be provided in addition.

In the above embodiment, when the back cover 12 as the inspection cover is removed, the engagement is released by lifting, that is, moving upward.
It is also possible to adopt a configuration in which the engagement is released by moving in the width direction. In this case, it is apparent that the locking and unlocking by the lock rod 8 can be performed.

[0046]

As described above in detail, in the interlock device for the closed switchboard according to the first aspect of the present invention, the locking means of the inspection cover of the cable room provided with the load-side conductor is used for grounding the load-side conductor. Since the locking or unlocking operation is performed in mechanical linkage with the movable part of the provided grounding switch, opening of the inspection cover when grounding is not performed can be reliably prevented, and safe inspection work can be performed. .

In the interlock device for a closed switchboard according to the second aspect of the present invention, the inspection cover is disengaged from the outer case by being moved in one direction within the mounting surface so that the inspection cover can be opened. A lock rod which is pushed and pulled through a connecting link by a movement of a movable portion of the grounding switch to contact a part of the inspection cover, and restricts the movement of the inspection cover to restrict the inspection cover to a closed state. Therefore, a secure lock state can be obtained with a simple configuration.

In the interlock device for a closed switchboard according to the third aspect of the present invention, a reinforcing rib provided on the inner surface of the inspection cover is used as a contact member with the lock rod. It is not necessary to provide the components described above, and the configuration can be further simplified.

Further, in the interlock device for a closed switchboard according to the fourth aspect of the present invention, the connecting portion of the operating link of the grounding switch is shared as the connecting portion of the connecting link of the lock rod. The present invention has an excellent effect, for example, there is no need to add a dedicated component for connection to the device, and the configuration can be further simplified.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a schematic configuration of a closed switchboard provided with an interlock device according to the present invention.

FIG. 2 is a front view of the closed switchboard shown in FIG.

FIG. 3 is a rear view of the closed switchboard shown in FIG. 1;

FIG. 4 is an enlarged sectional view of a main part showing a mounting structure of a back cover of a closed switchboard as an inspection cover.

FIG. 5 is a view taken along line VV of FIG. 4;

6 is a sectional view taken along line VI-VI in FIG.

FIG. 7 is a side view showing a configuration of an interlock device according to the present invention together with an operation mechanism of a grounding switch.

FIG. 8 is a side view showing the configuration of the interlock device according to the present invention together with the operation mechanism of the grounding switch.

[Explanation of symbols]

1 outer box, 3 cable room, 6 grounding switch, 12, 13
Back cover, 12a Reinforcement rib, 17 engagement pin, 18 engagement hole, 30
Load side conductor, 40 breaker, 80 lock rod, 81 connecting link.

Claims (4)

[Claims] 1. A bus-side branch conductor connected to a common bus, a load-side conductor connected to a power transmission cable to a load,
A drawer-type switchgear that connects and separates both conductors, a grounding switchgear that grounds a part of the load-side conductor by a predetermined operation during drawing of the switchgear, and is formed inside an outer box that houses these. An inspection cover that is openably and closably mounted in a cable room in which the load-side conductor is disposed, and mechanically interlocks with a movable part of the grounding switch, allowing the inspection cover to be opened during grounding, and A lock means for restraining the inspection cover in a closed state during release. 2. The inspection cover is configured to be disengageable from the outer case by being moved in one direction within the mounting surface and openable, and the locking means is provided with a tip of the inspection cover at a part of the inspection cover. A lock rod that contacts and restrains the movement, connects the lock rod and a movable part of the grounding switch, and pushes and pulls the lock rod in the axial direction to change the contact position and the non-contact position. 2. The interlock device for a closed switchboard according to claim 1, further comprising: a connecting link moved between the closed switchboards. 3. The interlock device for a closed switchboard according to claim 2, wherein a tip end of the lock rod is configured to abut against a reinforcing rib provided on an inner surface of the inspection cover. 4. A connecting portion between the connecting link and the grounding switch,
The interlock device for a closed switchboard according to claim 2 or 3, wherein the interlock device is shared with a connecting portion of an operation link of the grounding switch.