Central switchgear

1.1 High and low structure and constant height structure

The standard middle cabinet is of high and low structure, with a front height of 2300mm and a rear height of 2000mm. The height of the isometric structure is the same, as shown in Figure 1. The bus bar of the high and low cabinet is arranged in the shape of the product, and the instrument room is an independent structure and can be disassembled. The busbar of the contour cabinet is arranged in a vertical shape, and the instrument room and the cabinet body are an integral structure. The equal height structure has larger installation space than the high and low structure, and is also easy to make, operate and maintain.

Figure 1 Central switchgear

Figure 1 Central switchgear

1.2 Rear Grounding switch and Middle Grounding switch of the middle cabinet can be installed in two ways: rear grounding switch and middle grounding switch, as shown in Figure 1. When the ground switch is rear, you must enter the lower front cabinet door of the middle cabinet for cable construction or maintenance, which is inconvenient for construction. The front and back doors of the cabinet should be interlocked with the ground switch. When the ground switch is set in the middle, the cable can be accessed through the lower cabinet door at the rear for construction or maintenance. Usually THE BOTTOM OF THE CABINET before AND after BOTH sides are separated with iron plate, the front side DOES not have LIVE conductor, THE back door and THE GROUND switch UNDERTAKE "5 PREVENT" interLOCK. In the cabinet basically uses the ground switch in the height structure.

Improve the safety distance

There are two kinds of standard central cabinet cabinets: 1500mm deep cable outlet cabinet and 1660mm deep overhead outlet cabinet. When the overhead wire outlet cabinet is used for the wire intake of the busbar bridge of the main transformer cabinet, the effective distance between the live part and the rear board of the busbar chamber is less than 125mm, which cannot meet the safety distance requirements.

The site improvement measure is to add epoxy resin insulation board on the back plate of the bus room. Now manufacturers usually increase the depth of overhead outlet cabinet to 1700mm, basically solving the problem of safe distance, or design the depth of cable outlet cabinet and overhead outlet cabinet to 1600mm and 1800mm.

3. Improve the function of "five defenses"

The central cabinet is coordinated with the chassis of the circuit breaker handcar through the transmission mechanism of the cabinet body to realize the "five prevention" function of electrical operation. Under some new electrical conditions and operation modes, part of the "five prevention" function of the central cabinet can not meet the requirements, so it is necessary to improve the "five prevention" function.

3. Improve the function of "five defenses"

The central cabinet is coordinated with the chassis of the circuit breaker handcar through the transmission mechanism of the cabinet body to realize the "five prevention" function of electrical operation. Under some new electrical conditions and operation modes, part of the "five prevention" function of the central cabinet can not meet the requirements, so it is necessary to improve the "five prevention" function.

3.1 Ground switch latching

When the power line uses the "hand-in-hand" power supply mode and the circuit breaker in the central cabinet is located in the test position, the outgoing side may still be supplied from other substations. Before closing the grounding switch, ensure that there is no power at the outlet side. There are three main locking operations.

First, the use of the inspection trolley. Before closing the grounding switch, pull the circuit breaker trolley out of the cabinet, then push it into the test trolley, and close the line grounding switch after the test confirms that there is no voltage.

Second, open the door. When the circuit breaker is in the test position and the live display device detects that there is no voltage in the line, open the cabinet door and confirm that there is no voltage. Then close the ground switch.

Third, rely on the line side live display locking device. As long as the line side is live and the latching device indicates that there is no power and the latching is opened, the grounding switch can be operated.

Method 1 has a large amount of operation, which is equivalent to two times of power failure operation without electric trolley inspection. Now there are only bus electric inspection and grounding operation, and special electric trolley inspection and grounding are used. Method 2 is adopted by some power departments, and the operation procedure is more complicated.

Method three is to adopt a more way. When the circuit breaker is in the test position, the ground switch can be used only when there is no power on the line side, and the live display device is electric and normal, and the locking electromagnet is electric and normal. If either the live display device or the locking electromagnet fails or loses power, the closing operation will not be possible. There has been no live grounding switch accident due to live display device locking fault. When the live display sensor is faulty or disconnected, it will be reflected by the indicator light on the live display. Please visit:

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