Medium Voltage Metal Enclosed Switchgear

The body and the interval boards of the cabinet are bolt by aluminum zinc alloy board after the process of CNC machine tool and multi bending technology, so that the cabinets assembled can guarantee the unity of the structure and the dimension. The aluminum zinc alloy board has the functions of corrosion resistance and oxidation resistance, and has the higher mechanical robustness than the ordinary steel board. The cabinet is divided to drawer room, bus bar room, cable room and relay instrument room by the interval boards with each unit grounding separately. The doors of the cabinet are all handled with the technology process of electrostatic gunning to make the surfaces have the advantages of anti-impaction, corrosion resistance, and beauty and so on.

The drawers can be classed to circuit breaker drawer, voltage transformer drawer, metering drawer, separation drawer and station used variety drawer according to different usage. The drawers with the same usage can exchange each other. The drawers have test/separating and working positions inside the cabinet, each position with an interlock unit to ensure the drawers can't move freely in the above two positions.

A special channel has been installed in the isolation room to provide the drawer to move. When the circuit breaker is moving between the test position and the working position, the separating valve automatically opens or closes to ensure that the operating staff can't get in touch with the charged body. The drawers can be operated in the condition that the cabinet door is closed. The position where the drawer is inside the cabinet can be seen through the monitoring window, and any of the labels on the drawer can also be seen. All these guarantee the safety of the operating and the maintenance staff.

The main bus bar is lead from one cabinet to another cabinet and it is firmed by branch little bus bar and electrostatic contact box. It is fixed by bus bar bushing when it goes through the side wall of the neighbor cabinet.

Adequate cable room not only can connect many cables, but also can install current transformer, grounding switch and lightning arrester and so no.

The internal plate and the panel of the relay room can install control and protection elements, the meter, the displaying instrument and the monitoring indicator and so on secondary elements.

The cabinet has a reliable interlock unit in accordance with the "five-prevention" requirement, which actually guarantee the safety of the operating staff and the device:

a. An attention button and an alternation switch KK are installed on the room door to avoid the error switch on/off of the circuit breaker;

b. The circuit breaker can not move after switching on in working position to avoid the error pull or close of the separating contact;

c. The grounding switch can switch on only the drawer of the circuit breaker exits the cabinet and the drawer can not enter the cabinet at the same time (the grounding switch can match a voltage monitoring unit). The grounding switch can not switch on when the drawer is in the cabinet, thus fulfill the preventions of closing the grounding switch with power and closing the circuit breaker before the grounding switch is open;

d. The bottom door and the back door can not open after the circuit breaker entering the cabinet to avoid the error entry with power interval;

e. The drawer of the circuit breaker can switch off manually only without switching on when it actually is in test or working position and has no control voltage;

f. The secondary plug is locked and can not be pulled out when the drawer is in working position.

In the cable room, TMY40*4 grounding bus bar has been set independently. This bus bar can go through every neighbor cabinet and can get a good connection with the cabinet body to ensure the safety of the operating staff and the cabinet body.

Pressure releasing units have been set at the upside of the drawer room, bus bar room and the cable room. When the circuit breaker or the bus bar arises inner electric arc, with the appearance of the electric arc, the air pressure in the cabinet grows and the pressure releasing unit will automatically open to release the pressure and air when the pressure reaches up to a certain value to ensure the safety of the operation staff and the cabinet body.