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Abnormal analysis and accident treatment of power capacitor
Addtime:2012-01-11 16:19:47

The power capacitor is a static reactive power compensation device, whose main function is to provide reactive power to the power system. The use of local reactive power compensation can reduce the transmission current of transmission lines, and play an important role in reducing line losses, improving power quality and improving equipment utilization.


1, analysis and treatment of abnormal operation of capacitor


1) abnormity analysis


Overvoltage: the capacitor can be allowed to run over 5% of the rated voltage, and allow short-term operation at 1.1 times the rated voltage. Long over-voltage operation will cause the capacitor to heat and accelerate the insulation aging. Capacitors should be avoided operating at the highest voltage and maximum temperature simultaneously.


Overcurrent: it can be allowed to operate at no more than 1.3 times the rated current, but the overvoltage and higher harmonics in the medium and long term should be eliminated.


Leakage oil: seal is not strict, then air, water and other impurities may enter the interior, resulting in the reduction of internal insulation. During operation, leakage of oil from power capacitor housing and welds should be immediately checked out to ensure the safety of capacitor banks.


Temperature: when the air temperature is 40 degrees, the temperature of the shell of the power capacitor shall not exceed 55 degrees.


2) fault treatment


Common failures: A, capacitor housing expansion drum or oil seepage; B, capacitor casing rupture, flashover with sparks; C, capacitor internal short circuit, sound abnormal or injection fire; D, capacitor shell temperature above 55 degrees centigrade, show temperature wax melted.


Treatment: when a or capacitor is injected or exploded, the power should be disconnected immediately and extinguish with sand or dry extinguisher. Such accidents are mostly caused by internal and external overvoltages and serious internal faults of capacitors. No reclosing should be used for capacitors and no strong delivery after tripping. B, switch trip, and the shunt fuse is not broken. After 3 minutes of discharge, the circuit breaker, CT, cable and capacitor will be checked. If no problems can be found, inspection tests should be carried out. C, when fuse is fused, it should be reported to the dispatcher. After obtaining the agreement, the capacitor switch will be switched on. After cutting off the power supply and discharging it, the external inspection is carried out first, such as whether there is no flashover trace on the outer casing, the shell is deformed, the oil leakage and the grounding device have short circuit, and then the insulation resistance value of the poles and the very opposite ground is measured by the insulation shake table. If the fault traces are not found, the fuse can be put into operation after the fuse is changed. If the power supply is also fused, the fault capacitor should be exited and the other part of the power supply should be restored.


3) handling the safety matters in the case of failure


After opening the switch and the switch, the capacitor should be discharged. After discharge of the capacitor, the capacitor should also undergo a manual discharge. At the time of discharge, the earthing end of the grounding wire is first connected, and the capacitor is discharged many times with the grounding rod until the discharge spark and the sound are released, then the grounding end is fixed. Because the fault capacitor may have bad lead contact, internal breakage or fuse breakage and so on, there may still be part of the charge is not exhausted, so before contact the fault capacitor, the maintenance personnel should also wear insulation gloves, first use short route to disconnect the two poles of the fault capacitor, and then disassemble it.