1. Parallel operation of transformers:

Voltage ratio (allowable phase difference ±0.5%), impedance voltage (allowable phase difference ±10%), transformers of the same wiring group can be operated in parallel, if the voltage ratio and impedance voltage are different, they must be calculated , When running in parallel, any one of them is not overloaded. (The capacity is 3:1)

Before paralleling and de-arranging the transformers, check the load distribution and write the check statement into the switching operation ticket.

Before the transformers that are newly put into operation or have undergone major repairs, they should be verified and verified before they can be paralleled.

2. Transformer's power failure

Before the transformer is shut down and transmitted, the neutral point switching problem should be considered to ensure that the number of directly grounded neutral points remains unchanged after the power is cut off. For the directly grounded neutral point of 110kV and above, the neutral point grounding switch of another transformer should be closed first, and then the original neutral point grounding switch should be opened; if it is a 35kV arc suppression coil for switching, you should Open the neutral grounding switch of the transformer that has been closed, and then close the neutral grounding switch of another transformer.

When the transformer is out of power, stop the low-voltage side first, then stop the medium-voltage side, and stop the high-voltage side. When operating, disconnect the circuit breakers on each side first, and then open the isolation switches on each side in order from low to high. For the main transformer isolation switch, the transformer side should be pulled first, and then the bus side. The sequence is reversed when power is sent.

The strong oil-air-cooled transformer should be put into the cooler before putting it into operation.

3. Transformer on-load tap changer operation

For parallel operation of transformers, the voltage regulation operation should be carried out step by step in turn, and two or more tap changes shall not be performed continuously on one transformer.

When the main transformer is overloaded, no on-load tap change operation is allowed.

After the on-load tap-changer has been operated for 6-12 months or 2000-4000 times of switching, oil samples should be taken for testing. After 1-2 years of operation or 5000 times of switching, the on-load tap-changer box should be replaced After switching 5000-10000 times, the tap changer should be checked for lifting core.

4. Bus operation

When the busbar is powered off, the secondary switching of the voltage transformer should be done to prevent the secondary side of the voltage transformer from charging the busbar.

When the bus tie breaker is used to charge the bus, the bus tie breaker charging protection should be turned on, and the charging protection will exit when the charging is normal.

For inverted busbar operation, the relevant line protection and bus differential protection should be switched on and off according to regulations. The bus tie breaker should be set as a dead switch before bus inverted.

For bus charging operation, in general, the charging operation should be carried out directly with a voltage transformer.

5. Isolation switch operation

⑴It is forbidden to use the isolating switch to pull the load equipment or load line.

⑵It is forbidden to open and close the no-load transformer with an isolating switch.

⑶Operation permitted with isolation switch:

a. Open and close the trouble-free voltage transformer and arrester.

b. When there is no fault in the system, open and close the neutral grounding switch of the transformer.

c. Open and close the loop current without impedance.

d. The outdoor triple disconnect switch can be used to open and close the load current with a voltage of 10kV and below, and a current of below 9A; when it exceeds the above range, calculations, tests, and approval by the chief engineer of the competent unit are required.

⑸When the voltage transformer is powered off, first disconnect the secondary air switch (or remove the secondary fuse), and then open the primary isolating switch. The operation sequence is the opposite when power is supplied. Two sets of voltages on the primary side that are not running in parallel Transformers are prohibited from paralleling the secondary side.