Common fault handling of high voltage voltage transformer

1. The treatment of 220kV voltage transformer secondary small switch trip or secondary fuse blown

1. Abnormal phenomena

(1) Busbar voltmeter, the active meter dynamometer is reduced to zero.

(2) 220kV outlet or main transformer "AC voltage disappears" signal appears, the distance protection device is faulty, 220kV busbar "low voltage" is dropped.

(3) The fault recorder may be in motion.

2, exception handling

(1) Reporting and dispatching.

(2) Disabling the line distance protection (interphase and grounding) and high frequency blocking protection on the bus.

(3) Deactivate the fault recorder.

(4) Test the secondary switch. If it is unsuccessful, it should report to the section (zone) for processing.

(5) It is not allowed to use the 220kV bus voltage transformer secondary parallel switch to parallel the secondary and secondary voltage secondary circuits to prevent accidents from expanding.

220kV I, II female PT secondary parallel switch, normal operation should be disconnected, such as in the double busbar wiring, only when the 220kV hot reverse bus, that is, the bus coupler switch is closed and changed to non-automatic, to prevent voltage switching The intermediate relay is subjected to an excessive unbalanced load, and the PT secondary parallel switch is thrown, and the parallel switch is terminated, and the parallel switch is separated before the bus switch is changed to automatic.

220kV, 110KV bus PT switching device When the DC fuse is blown, the AC voltage of the line reclosing switch disappears, the oscillation blocking action or the distance protection device fails, and the AC voltage disappears. The distance and zero sequence protection are blocked. The dispatch should be reported immediately, and the DC fuse should be replaced after the distance protection is deactivated. The 220kV voltage transformer has two fast air switches. If one of the air switches is out of phase or tripped, it is reflected in the obvious change of the voltmeter, and should be checked immediately.

Second, the 500kV voltage transformer's secondary small switch trip or fuse blown

1. Abnormal phenomena

(1) The voltage circuit corresponding to the voltage transformer is disconnected, and the voltage loss signal is protected.

(2) The voltmeter corresponding to the voltage transformer indicates low or no indication, and the indicator of the reactive or reactive meter is reduced or zero.

2, exception handling

(1) Report the dispatch to the application and apply for the suspension of the relevant protection.

(2) Replace the fuse or close the secondary small switch.

(3) If the secondary small switch still trips to indicate that the secondary circuit is short-circuited, it should be notified to the relevant department for handling.

Third, the treatment of the failure of the ontology

1. Abnormal phenomena

(1) The body has overheating.

(2) There are discharge sounds and abnormal noise inside.

(3) The oil level rises and carbonaceous, 220kV voltage transformer equipped with metal expander, the red line position in the monitoring window is too high.

(4) There is leakage oil phenomenon.

2, exception handling

(1) Immediately report the relevant situation to the dispatcher and relevant leaders, and apply for power outage.

(2) 220kV voltage transformers have general faults, which can be isolated by knife gate. When the fault is serious, it is strictly forbidden to use knife gate isolation. The power can only be cut off by the bus coupler switch.

(3) When the 500kV voltage transformer fault is to be deactivated, the corresponding bus or line must be deactivated.

Fourth, the voltage transformer body is on fire

When the transformer is on fire, immediately disconnect the relevant power supply, isolate the fault voltage transformer, report to the dispatch, and use dry fire extinguisher or sand to extinguish the fire.

5. Abnormality and fault handling of 35kV voltage transformer

The voltage transformer itself is faulty and should be applied for deactivation if one of the following conditions occurs.

(1) The high-voltage fuse is blown two or three times in succession.

(2) The temperature of the transformer is too high (when the system is grounded, the neutral grounding isolating switch should be opened for 2h, and the PT should be disabled when there is no grounding isolating switch).

(3) There is a click or other noise inside the transformer.

(4) There is a phenomenon of oil leakage or glue flow in the TV or at the exit of the lead (a large amount of oil leakage or PT flow glue).

(5) A odor or smoke is emitted from the transformer.

(6) There is a spark discharge between the winding and the casing or between the casing and the ground.

A fault occurs inside the voltage transformer, which often causes a fire or explosion. If it is found that the high voltage side insulation of the voltage transformer is damaged (such as smoke or severe internal discharge), the power circuit breaker should be used to cut off the fault voltage transformer. At this time, it is strictly forbidden to disconnect the faulty voltage transformer with the isolating switch. Because the isolating switch has no arc extinguishing capability, if the fault is cut off by the isolating switch, the busbar may be short-circuited, causing damage to the equipment or personal accident.

No switches are installed on the voltage transformer circuit. If the fault is directly removed by the power circuit breaker, it will directly affect the user's power supply, so it should be processed according to the actual situation on site. If the time allows the necessary reverse bus operation, the power supply to the user will not be affected when the faulty voltage transformer device is opened. If the voltage transformer smokes or catches fire, and it is too late to carry out the reverse bus, the bus power line breaker should be pulled open immediately, then the fault voltage transformer isolation switch is opened to isolate the fault, and then the bus operation is resumed.

(1) 35kV bus voltage transformer secondary fuse blown (or fast small switch jump one phase)

1. The fault phenomenon is as follows.

(1) The fusing phase voltage and line voltage are seriously degraded, the active and reactive meter indications are lowered, and the electric energy meter is slow.

(2) The main transformer 35kV circuit disconnection blocking device will be activated, and the voltage circuit of the capacitor will be blocked.

2. The processing method is as follows.

(1) Report to the dispatcher. Use the voltmeter switch to switch the phase voltage or line voltage to distinguish which phase fuse is blown.

(2) Disable the connection piece of the busbar that may be protected by false tripping (such as 35kV distance protection, low frequency).

(3) Check whether the relay protection personnel work in the secondary circuit of the 35kV bus voltage transformer, and the accidental contact causes the open circuit or short circuit.

(4) Replace the fuse test. If it is not successful, remove the 35kV feeder and the main transformer voltage loop fuse (central signal, low frequency disk).

(5) Try again to the small bus. After the success, the feeders are tested one by one. If it is blown again, it indicates that there is a short circuit in the voltage circuit of the line, and the fuse should be removed. After the low-voltage side of the voltage transformer is restored, the dispatch is reported, so that the relay protection personnel can be dispatched to the substation for processing.

It must be noted that after the secondary fuse of the voltage transformer is blown, the secondary circuit of the voltage transformer must not be operated in parallel or in contact.

(2) 35kV bus voltage transformer high-voltage fuse blown

1. The fault phenomenon is as follows

(1) The phase voltage of the fusing phase is reduced or close to 0, the phase voltage of the intact phase is constant or slightly decreased, and the line voltage may drop when the circuit phase is switched to the good phase (the actual operation is like breaking and non-breaking), and the voltage transformer is active. The reactive power meter indicates a decrease and the energy meter is slow.

(2) Main transformer 35kV "voltage loop disconnection". Capacitor "voltage loop disconnection" (protected bus voltage transformer), "busbar grounding" and 35kV "broken without return" alarm.

(3) When checking the high-voltage fuse, there may be a click.

2, the processing method is as follows

(1) Report to the dispatcher. The phase switch or line voltage can be switched with a voltage switch to determine which phase is faulty.

(2) Deactivate the tripping plate on the busbar that may malfunction (distance, low frequency).

(3) Pull open the voltage transformer isolation switch, and after replacing the safety measures, replace the high-voltage fuse of the same specification. If the trial run is unsuccessful and the fuse is continuously blown, it may be an internal fault of the transformer. The schedule should be reported and the cause identified.

(4) If the internal fault of the voltage transformer is checked, the insulator part of the high-voltage fuse casing can be touched by hand to find out whether it is internal overheating. It can also be judged by shaking the insulation resistance of the table. When the internal fault of the transformer is confirmed, the work area and dispatch should be reported.