Common Fault of Transformer and Treatment 

I. Voltage Transformer

1. If a voltage transformer has one of the following faults, it shall be stopped at once:

(1) HV fuse is fused twice continuously (10kV voltage transformer);

(2) Internal heat and too high temperature;

(3) “Crackling” of discharge or other noises inside;

(4) Empyreumatic taste, smoke or fire inside;

(5) Serious fracture discharge of sleeves, spark discharge between sleeves, lead and shell;

(6) GIS transformer has air leakage or SF6 gas pressure is lower than the minimum operating pressure;

2. When serious fault is found in voltage transformer, treatment procedures and general method are:

(1) Quit protective and automatic device which may have mal-operation, and disconnect secondary switch of fault voltage transformer (or pull secondary fuse).

(2)

(3) Disconnect the isolation switch to isolate fault if HV fuse is fused but insulation on HV side is not broken.

(4) When HV fuse is not fused, but the voltage transformer has serious fault and HV insulation side is broken, it is prohibited to use isolation switch or take down the fuse to judge voltage transformer with fault. The only method is to switch fault through fuse, and disconnect the isolation switch in electrically neutral condition to restore power supply.

(5) Fault isolation. After paralleling of primary bus, connect second contact of the voltage transformer to put into the protection and automatic device again.

(6) Fire extinguishment through 1211 fire extinguisher

3. Treatment of fusing of primary fuse wire of 10kV voltage transformer:

(1) Phenomenon: voltage of fusing phase decreases or approaches zero, voltage of phase in good condition remains or slightly decreases, and indication of active and inactive power meters decreases.

(2) Treatment: disconnect the isolation switch of the voltage transformer, take down LV fuse wire, take safety measures, inspect whether there is external fault, and change primary fuse wire with the same specification. If continuous fusing occurs in power transmission, the transformer many have internal fault. Therefore, the voltage transformer shall be stopped.

4. Treatment of fusing of secondary fuse wire 10kV voltage transformer:

(1) Phenomenon:

1) Voltage circuit disconnection signal of voltage transformer shows, and alarm bell rings.

2) Fault phase voltage is zero or low, indication of active and inactive power meters is zero or low.

(2) Treatment method:

1) Check whether the protector of secondary voltage circuit is fused or has poor contact.

2) If the protector has fault, report it to the dispatcher on duty instantly.

3) Check whether the voltage loop has loose connection or disconnection.

4) If the reason cannot be found and the fault cannot be eliminated, conduct power cut for inspection at once.

5. Treatment of accident of 110kV voltage transformer:

The primary side of 110kV voltage transformer and above has no fuse for protection and a LV automatic switch is used on the secondary side to disconnect short-circuit current of secondary loop.