Common Fault of Transformer and Treatment 

I. Voltage Transformer

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

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

(2) Internal heat and temperature is too high;

(3) There is a discharge "crackling" sound or other noise inside;

(4) Empyreumatic odor, smoke or fire inside;

(5) The casing is severely ruptured and discharged, and there is spark discharge among the casing, the lead and the shell;

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

2. When serious errors above are found in voltage transformer, treatment procedures and general troubleshooting solutions are:

(1) Exit the protective and automatic devices which may have mal-operation, and disconnect secondary switch of the faulty voltage transformer (or pull secondary fuse).

(2) Disconnect the isolation switch to isolate error if HV fuse is not fused and insulation on HV side is not broken.

(3) When HV fuse is not fused, but the voltage transformer has serious error and HV insulation side is broken, it is prohibited to use the isolation switch or take down the fuse to disconnect the faulty voltage transformer. The error can only be removed with a circuit breaker,, and disconnect the isolation switch without power, and then restore power supply.

(4) After the isolating of errors and paralleling of primary bus, connect secondary switch of the voltage transformer and put into the protection and automatic devices again.

(5) Extinguish fire via 1211 fire extinguisher

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

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

(2) Treatment: disconnect the isolation switch of the voltage transformer, remove the LV fuse , take safety measures, and inspect and make sure there is no external error, then change primary fuse of the same specification. If continuous fusing occurs during power transmission, the transformer many have internal fault. Therefore, the voltage transformer shall be stopped.

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

(1) Symptoms:

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

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

(2) Treatment:

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

2) If it is not the problem of the protector, report it to the dispatcher on duty instantly.

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

4) If the cause cannot be found and the error cannot be eliminated, conduct power outage check immediately.

5. Accident handling of the 110kV voltage transformer:

The 110kV and above voltage transformers have no fuse protection on the primary side, and the secondary side uses the LV automatic switch to disconnect the short circuit current of the secondary circuit.