Precautions for operation and maintenance of high-voltage switchgear

Precautions for operation and maintenance of high-voltage switchgear

1. The power distribution room should be moisture-proof, dust-proof, and prevent small animals from penetrating.

2. All metal parts should be rust-proof (painted with varnish or colored paint), moving parts should be lubricated, check whether the screws are loose, and the dust should be removed in time.

3. Observe the state of each component, whether there is overheating, discoloration, sound, poor contact, etc.

4. For vacuum circuit breakers:

a. When conditions permit, the power frequency withstand voltage should be carried out, and the vacuum degree can be checked indirectly.

b. For the glass bubble arc extinguishing chamber, it should be observed whether there is blackening on the internal metal surface and whether there is glow discharge and other phenomena.

c. When replacing the arc extinguishing chamber, the conductive rod should be stuck, and the bellows should not be subjected to torsional moment, and the conductive clip and the conductive rod should be clamped.

d. The specification of the closing circuit fuse should not be too large, and the melting characteristics of the fuse must be reliable.

e. When the closing fails, the fault must be checked: in the electrical aspect, the power supply voltage may be too low (the voltage drop is too large or the power supply capacity is not enough), the closing coil is damp and the inter-turn short circuit is caused, and the fuse is broken. In terms of mechanism, it may be that the amount of the closing lock is too small, the angle of the auxiliary switch is not adjusted well, and the power is cut off too early.

f. When the opening fails, the fault must be checked: in the electrical aspect, the power supply voltage may be too low, the transfer switch is in poor contact, and the opening circuit is disconnected. In terms of mechanics, it may be that the trip of the opening coil is not adjusted properly, the iron core is stuck, the latch is too large, and the screw is loose.

g. The switching time of the auxiliary switch contacts must be carefully adjusted. If the switching is too early, it may not be completed. If the switching is too slow, the deadlock coil will be charged for a long time and burn out. The correct position is to close at low voltage, just to close.

5. For isolating switch:

a. Pay attention to whether the blade and contact are twisted, and whether the closing is in place and the contact is good when closing.

b. Whether the fracture distance is greater than or equal to 150mm when opening.

c. Whether the support and push rod porcelain bottles are cracked or the plastic parts are loose.

d. Whether the interlocking device between its operating mechanism and the circuit breaker is normal and reliable.

6. For handcart isolation

a. The occlusal surface of the plug should be coated with a protective agent (conductive paste, Vaseline, etc.),

b. Pay attention to whether the plug has obvious deflection deformation.

c. During maintenance, pay attention to whether there is fusion welding on the occlusal surface of the plug.

7. For current transformers:

a. Pay attention to whether the connector is overheated, whether there is noise or odor.

b. Whether the insulation part is cracked or discharged.

c. Whether the lead screw is loose or not, it must not be opened, so as to avoid induced high voltage and cause damage to the safety of operators and equipment.

8. When the switchgear has not been put into operation for a long time, the main primary element intervals (such as handcart room and cable room) should be heated and dehumidified before putting into operation to prevent condensation from affecting the external insulation of the equipment.