Treatment of transformer accident
Writer： Hengfeng you electric Time：2023-04-10 views：times
According to article 6.1.2 of DL / t572-95 operation specification for power transformers, the transformer shall be shut down immediately under one of the following conditions. If there is a standby transformer in operation, it shall be put into operation as far as possible:
a. The sound of the transformer increases obviously, which is very abnormal, and there is a burst sound inside;
b. Serious oil leakage or fuel injection, so that the oil level drops below the indication limit of the oil level gauge;
c. The casing is seriously damaged and discharged;
d. The transformer is smoking and on fire.
1、 After automatic tripping of transformer, the following inspection and treatment shall be conducted:
① After the transformer trips automatically, the operator shall carry out systematic treatment, that is, put the standby transformer into operation, adjust the operation mode and load distribution, and maintain the operation system and its equipment under normal conditions.
② Check what kind of protection action and whether the action is correct.
③ Understand whether the system has faults and the nature of faults.
④ One trial power transmission can be conducted without external inspection under the following conditions: personnel mistouch, misoperation and protection misoperation; Only the low-voltage overcurrent or time limited overcurrent protection acts, and the next level equipment of the tripping transformer fails, but its protection does not act, and the fault point has been isolated.
⑤ In case of differential protection, gas protection or quick break overcurrent protection and impact in case of fault, it is necessary to conduct detailed inspection on the transformer and its system, cut off the power and measure the insulation. It is forbidden to put the transformer into operation until the cause is found out or handled.
2、 Gas protection action (tripping) when the gas protection action of transformer trips, the following inspection and treatment shall be carried out:
a) Collect the gas of the gas relay for chromatographic analysis. If there is no gas, check whether the secondary circuit and the terminal and lead of the gas relay are well insulated.
b) Check whether the oil level, oil temperature and oil color change;
c) Check whether the explosion-proof pipe is broken or not;
d) Check whether the transformer shell is deformed and whether the weld is listed.
e) If no abnormality is found after inspection and it is confirmed that the malfunction is caused by the fault of the secondary circuit, the gas protection can be connected to the signal or exited when the differential protection and overcurrent protection are put into operation, the power supply can be tested once, and the monitoring can be strengthened.
f) If there is gas in the gas relay or there are problems in items a, B, C and D above, power off inspection and corresponding treatment shall be carried out, and put into operation after passing the inspection and test.
3、 When the over-current protection action of transformer trips, the following inspection and treatment shall be carried out:
a) Check whether the bus and the equipment on the bus have short circuit and sundries;
b) Check whether several measuring equipment of transformer are short circuited;
c) Check whether the low-voltage side protection acts and whether the protection of each line acts.
d) When it is confirmed that the bus has no power, the line carried by the bus shall be opened.
e) In case of bus failure, bus switching or load transfer shall be considered.
f) After inspection, if it is confirmed that it is a step-by-step trip, try to power on once.
g) When the trial power transmission is good, find out the fault line one by one.
h) If it is caused by the circuit, the power can be transmitted only after the fault factor is eliminated.
4、 After the transformer differential protection action trips, the following inspection and treatment shall be carried out“
a) Check whether the transformer is abnormal, whether the insulator within the scope of differential protection is flashover and damaged, and whether the lead is short circuited.
b) If the equipment within the scope of differential protection has no obvious fault, check whether the relay protection and secondary circuit have fault and whether the DC circuit is grounded at two points.
c) There is no fault after the above inspection. After reporting to the chief engineer for approval, the step-up pressurization test shall be carried out when the load is disconnected, and it shall be put into operation after it is in good condition.
d) In case of misoperation caused by relay and secondary circuit, the differential protection can be exited and the transformer can be put into operation.
e) When differential protection and gas protection act at the same time to trip the transformer, the transformer shall not be put into operation without internal inspection and test.
5、 Fire treatment principle of transformer: power failure - oil drainage - fire extinguishing.
① Power failure: if the transformer is on fire and the protection does not trip automatically, first disconnect the circuit breakers and disconnectors connected to it, and exit the cooler to disconnect its power supply. If the operation of adjacent equipment is endangered, it shall also be contacted in time to stop the operation of adjacent equipment.
② Oil drainage: if the oil overflows and catches fire on the top cover of the transformer, open the oil drainage valve at the lower part of the transformer to drain the oil to the accident oil pool so that the oil level of the transformer is lower than the fire level; If the internal fault of the transformer causes fire, the oil cannot be drained to prevent explosion; If the transformer shell is broken and there is oil overflow, close the electric drain valve of the transformer oil pool, open the electric drain valve and drain the oil to the accident oil pool of the main transformer.
③ Start the fire pump, open the fire valve and spray it to the transformer.
④ Report to the superior and start the emergency plan.
⑤ Notify and assist the fire department. Note: it is allowed to participate in fire extinguishing without endangering personal safety. It is best to use carbon dioxide, carbon tetrachloride, dry powder fire extinguisher and dry sand when extinguishing; Firefighters should wear gas masks; Special personnel shall be assigned to command the fire extinguishing to prevent casualties.
