JP4661432B2 - Pull-out type circuit breaker - Google Patents

Description

  The present invention relates to a draw-out type circuit breaker housed in a closed switchgear panel, and more specifically, a through-type current transformer that is arranged on the back of a cradle on which a breaker body is mounted and is connected to a main circuit conductor on the panel side. The present invention relates to an assembly structure of a bushing with a vessel.

As is well known, various types of equipment such as circuit breakers and current transformers for main circuit current measurement are stored in closed switchgear, and in particular, circuit breakers should be maintained and inspected relatively frequently. In many cases, a lead-out type circuit breaker is used (see, for example, Patent Document 1).
In addition, this lead-out type circuit breaker has a structure in which a through-type current transformer is adopted as an instrument current transformer for detecting overcurrent, and is provided on the back of the cradle and attached to a bushing connected to the main circuit conductor on the panel side. Has already been commercialized.
Next, FIG. 4 shows a conventional structure of the above-described drawer type circuit breaker. In the figure, 1 is a circuit breaker body (for example, a vacuum circuit breaker), 2 is a cradle mounted with a circuit breaker body 1 to guide and support it from the operating position to the test position and forward / backward movement (arrow direction). Contacts (terminals) corresponding to each phase breaker (vacuum valve) drawn from the breaker body 1 to the back side, 4 is a conductor bar of the main circuit laid on the panel side, and 5 is placed on the back side of the cradle 2 A bushing that insulates and supports the conductor bar 4 inserted into the bushing, and 6 is a through-type current transformer that is fitted and arranged on the outer peripheral side of the bushing 5.

When the circuit breaker body 1 mounted on the cradle 2 is pushed into the operating position in the above-described drawer type circuit breaker, the contact 3 is connected to the conductor bar 4, and when the circuit breaker body 1 is pulled out to the disconnect position, the contact 4 and the conductor bar 4 is disconnected.
5, the contact 3 is a horizontal flat conductor, the board-side conductor bar 4 is a vertical flat conductor, and a concave groove 3 a is formed at the tip of the contact 3. When the circuit breaker body 1 is pushed into the operating position, the conductor bar 4 is fitted into the concave groove 3a and the contact / conductor bar is connected.
As is well known, the through-type current transformer 6 measures the main circuit current using the conductor bar 4 as a primary conductor, and the outer shape of the main body is a ring shape, and is fitted on the outer periphery of the bushing 5 as shown in FIG. It is fixed and held in this position.
JP 2000-295724 A

  By the way, the drawer-type circuit breaker having the conventional structure shown in FIG. 4 has the following problems particularly in maintainability of the through-type current transformer. That is, the circuit breaker body 1 mounted on the cradle 2 and housed in the switchgear panel can be accessed from the front side of the switchgear and pulled out from the operating position forward during maintenance and inspection. On the other hand, since the through-type current transformer 6 attached to the circuit breaker is fitted and arranged on the outer peripheral side of the bushing 5 fixed to the back of the cradle 2, the breaker body 1 is mounted on the board. Even when pulled out, the current transformer 6 cannot be accessed from the front. For this reason, when the maintenance and inspection of the current transformer 6 and the replacement of parts are performed at the installation site of the switchgear, the conductor bar 4 of the main circuit is removed after accessing the inside of the panel from the backside of the switchgear. The current transformer 6 must be removed and reattached after it has been extracted from 5, and the maintenance work takes time. Moreover, there is a problem that the bus bar, cable, etc. are complicated and complicated on the rear side of the panel.

  The present invention has been made in view of the above points, and the object thereof is to solve the above-mentioned problems, and access from the front side of the cradle equipped with the circuit breaker body allows maintenance inspection and replacement work of the through-type current transformer. An object of the present invention is to provide a drawer type circuit breaker having an improved assembly structure of a bushing with a current transformer so that it can be easily and safely performed.

In order to achieve the above object, according to the present invention, a bushing with a current transformer on the back of a cradle in which a breaker body is movably mounted in a drawer type circuit breaker housed in a closed switchgear panel. Insulating and supporting each phase conductor bar on the panel side, and connecting the contact drawn out from the breaker body to the conductor bar at the circuit breaker operating position,
The bushing is an integrally formed product of a conductor bar insertion support corresponding to each phase, and a front open case that surrounds the periphery of the conductor bar insertion support and accommodates a through-type current transformer. Construct and accommodate a through-type current transformer inside the case, and then cover the open end surface of the case with a detachable insulating current transformer presser plate accessible from the front of the cradle. The container is held in a predetermined position (claim 1).
Further, as a specific mode, the bushing and the current transformer presser plate are configured as follows.
(1) A holding guide member for inserting a through-type current transformer from the front and supporting it in a fixed position is provided in the case portion of the bushing.
(2) The current transformer retainer plate has contact insertion holes drawn out from the circuit breaker main body on the plate surface, and contacts of each phase and insertion-type deformation on both the front and back surfaces of the plate. The insulation barrier between the phases with respect to the flow device is integrally formed, and is screwed to a mounting seat provided on the inner peripheral side of the case portion of the bushing so as to be fixedly attached to the open end surface.

According to the above configuration, the through-type current transformer is housed inside the case portion of the front opening type of the bushing disposed on the back surface of the cradle, and the current transformer is attached to the open end surface of the case portion from the front at this housing position. The holding plate is clamped and fixed at a predetermined position from the front and rear. As a result, during maintenance inspection of the through-type current transformer, the circuit breaker body is pulled out of the cradle and taken out of the switchgear panel, and then accessed from the front side of the cradle and attached to the case end of the bushing. By removing the current plate, the through-type current transformer can be easily pulled out from the bushing box to the outside with the board-side conductor bar fitted and supported in the bushing. Maintenance workability of maintenance inspection is improved.
The bushing case part and the current transformer retainer plate are structured as in claims 2 and 3, so that the through-type current transformer can be held in place without using a metal fastening member such as a screw. The current transformer retainer plate serves as an insulating partition for the charging part on the panel side and an insulating barrier between the phases to prevent electric shock and ensure insulation between the phases.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on the examples shown in FIGS. In addition, in the figure of an Example, the same code | symbol is attached | subjected to the member corresponding to FIG. 4, and the description is abbreviate | omitted.
That is, the drawer type circuit breaker of the embodiment shown in FIG. 1 is basically the same as the conventional structure shown in FIG. 4, but it is arranged on the back of the cradle 2 and the main circuit conductor bar 3 on the panel side is inserted. The supporting bushing 5 (resin-molded product) is integrally formed with an open front case portion 5a for housing the through-type current transformer 6 as will be described in detail later. After the current transformer 6 is housed, the through-type current transformer 6 is moved back and forth by the case part 5a and the current transformer holding plate 7 made of an insulator, which is attached from the front so as to cover the open end face side of the case part. And are fixed in place by a screwless method. In the figure, reference numeral 4a denotes a fastening screw for fixing the conductor bar 4 inserted into the bushing 5 from the back side to the bushing 5. Reference numeral 8 denotes an electric shock prevention shutter disposed in the cradle 2 so as to face the front of the bushing 5. The shutter is opened and closed in conjunction with the advance / retreat operation of the circuit breaker body 1, and the circuit breaker body 1 is pulled out. In the state, the shutter 8 moves to the closed position and serves to prevent an operator from touching the conductor bar 4 (charging part) behind the shutter 8.

Next, the detailed structure of the bushing 5 and the current transformer retainer plate 7 will be described with reference to FIGS. 2 is an exploded perspective view of the assembly of the bushing 5, the through-type current transformer 6 and the current transformer retainer plate 7. FIGS. 3A and 3B are views from the front and rear surfaces of the current transformer retainer plate. FIG.
Here, the bushing 5 has a total of six conductors corresponding to each phase (U, V, W, X, Y, Z phase) of the main circuit connected to the contact 3 on the power source side and the load side of the circuit breaker body 1. It becomes a resin-molded product of a box structure configured to interpose and hold the bars 4 (see FIG. 1) in a lump, and in the lower half of the bar 4 (see FIG. 1), it swells on the rear side so as to accommodate the through-type current transformer 6 The front open case part 5a is formed into a structure. In the upper half of the bushing 5, as shown in the figure, conductor insertion holes 5b corresponding to the U, V, and W phases of the main circuit are opened in a line in a row, and between them is forward. An interphase insulating barrier 5c projecting toward the end is formed.

In addition, the case portion 5a formed integrally with the lower half portion of the bushing 5 includes the conductor insertion hole 5b opened in the upper half portion and the X, Y, and Z phases that are inserted in the bushing while being aligned vertically. A conductor cover 5d that surrounds the tip of the corresponding conductor bar 4, and a through-type current transformer 6 that is inserted into the X and Z phase conductor bars at both ends excluding the center Y phase among the X, Y, and Z phases. The current guide 5e is formed by surrounding the conductor cover 5d so as to be fitted from the front and positioned and held at a predetermined position, and is distributed to the surrounding four locations, and arranged at the four corners on the inner peripheral side of the case portion 5a. A screw seat 5f to which the presser plate 7 is attached is formed, and the outer peripheral flange portion of the bushing 5 is overlapped on the back surface of the cradle 2 shown in FIG. Reference numeral 5g denotes guide rails of the shutter 8 formed at the left and right ends of the upper half of the bushing.
On the other hand, the current transformer retainer plate 7 that adheres to the opening end surface of the case portion 5a of the bushing 5 is set to be slightly smaller in outer size than the opening end surface of the case portion 5a. As shown in FIGS. 3 (a) and 3 (b), the insertion holes 7a for inserting the contacts 3 (see FIG. 1) of the circuit breaker body 1 corresponding to the X, Y, and Z phases are arranged in a horizontal row. It is open at. Further, an interphase insulating barrier 7b (see FIG. 3A) is provided on the front surface side, and an arc-shaped insulating barrier that surrounds the peripheral surfaces of the two through-type current transformers 6 from the left and right sides on the back surface side. 7c, and a convex portion 7d that is positioned inside the current transformer retainer plate 7 and presses against the end face of the current transformer (see FIG. 3 (b)), and further, screws are fastened to the four corners of the plate. The mounting seat 7e is formed, and the mounting seat 7e is overlaid on screw seats 5f (see FIG. 2) formed at the four corners of the case portion 5a of the bushing 5 and fastened with screws 9. Reference numeral 7f denotes a guide rail for the shutter (see FIG. 1).

  In order to incorporate the through-type current transformer 6 into the inside of the case part of the bushing 5 with the above configuration, the through-type current transformer 6 is inserted into the inside of the case part 5a from the front of the bushing 5 as shown in FIG. Then, the peripheral surface is fitted inside the holding guide portion 5e projecting from the inside of the case portion 5a and positioned and held at a predetermined position. Reference numeral 6 a denotes a secondary terminal portion of the current transformer 6. Next, the current transformer retainer plate 7 is attached to the opening end face of the case portion 5a of the bushing 5 and screwed, and in this assembled state, the through-type current transformer 6 housed in the case portion 5a of the bushing 5 is transformed. It is held at a predetermined position so as not to be pressed down by the presser plate 7 and fall off. 1, the bushing 5 is fixed to the back surface of the cradle 2, and the tip of the main circuit conductor bar 3 of each phase attached to the panel side at the position where the cradle 2 is stored in the switchgear panel is bushed. 5 is inserted into the conductor insertion hole 5 from behind and is fastened and fixed with screws 4a.

When the circuit breaker body 1 loaded into the switchgear panel and loaded in the cradle 2 is pushed into the operating position in this bushing assembled state, the contact 3 pulled out from the circuit breaker body 1 to the back as shown in FIG. The main circuit current is secondary output from the feedthrough current transformer 6 when energized.
When the through-type current transformer 6 is to be inspected or replaced after the switchgear is installed locally, the circuit breaker body 1 is pulled out of the cradle 2 and taken out of the switchgear panel, and then the cradle is emptied. 2 is accessed and the current transformer retainer plate 7 is removed, so that the operator does not need to access the panel from behind the switchgear as in the conventional structure (see FIG. 4). The current transformer 6 can be easily extracted forward from the case portion 5 a of the bushing 5. Moreover, even when the current transformer 6 is incorporated after maintenance inspection, the work can be performed by accessing from the front side of the cradle 2, thereby greatly improving the maintenance workability for the through-type current transformer 6 compared to the conventional structure. To be improved.

FIG. 3 is a configuration diagram of a drawer type circuit breaker according to an embodiment of the present invention, in which a circuit breaker body mounted on a cradle is pushed into an operating position and a contact is connected to a main circuit conductor bar on the panel side. Figure 1 is an exploded perspective view showing the assembly structure of the bushing, the through-type current transformer, and the current transformer retainer plate in FIG. FIG. 3 is a detailed structural diagram of the current transformer retainer plate in FIG. 2, wherein (a) and (b) are external perspective views as seen from the front surface and the back surface, respectively. Side view of the main part cross section showing the state where the circuit breaker body mounted on the cradle is pushed into the operating position and its contacts are connected to the main circuit conductor bar on the panel side in the configuration diagram of a conventional draw-type circuit breaker Schematic diagram showing connection structure between contact and conductor bar in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Circuit breaker body 2 Cradle 3 Contact 4 Main circuit conductor bar 5 Bushing 5a Case part 5e Current transformer holding guide part 5f Screw mount for current transformer retainer plate 6 Through-type current transformer 7 Current transformer retainer plate 7a Contact insertion hole 7b, 7c Insulation barrier 7e Mounting seat

Claims (3)

A drawer type circuit breaker housed in a closed switchgear panel. A bushing with a current transformer is installed on the back of the cradle where the breaker body can be moved forwards and backwards to provide insulation support for each phase conductor bar on the panel side. In the case where the contact drawn out from the circuit breaker main body is connected to the conductor bar at the operation position of the circuit breaker,
The bushing is an integrally formed product of a conductor bar insertion support corresponding to each phase, and a front open case that surrounds the periphery of the conductor bar insertion support and accommodates a through-type current transformer. Construct and accommodate a through-type current transformer inside the case, and then cover the open end surface of the case with a detachable insulating current transformer presser plate accessible from the front of the cradle. A drawer-type circuit breaker characterized in that the device is held in place. 2. A drawer-type circuit breaker according to claim 1, wherein a holding guide member is provided in the case portion of the bushing so as to insert the through-type current transformer from the front and support it in a fixed position. The drawer type circuit breaker according to claim 1 or 2, wherein the current transformer retainer plate has an opening for insertion of a contact drawn backward from the breaker body on the plate surface, and on both sides of the plate. Each phase contact and interphase insulation barrier for the insertion type current transformer are integrally molded, and are screwed to the mounting seat provided on the inner peripheral side of the bushing case and fixed to the open end face. Drawer type circuit breaker.

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