News
Cause of damage
Datetime: 2017-06-06 Visit: 7889
As power capacitors are put into operation more and more, but poor management and other technical reasons often lead to the destruction of power capacitors, resulting in the following reasons:
Capacitor internal component breakdown: mainly due to poor manufacturing process.
The capacitor is damaged by the insulation of the outer casing: the high-voltage side lead wire of the capacitor is made of thin copper sheet. If the manufacturing process is poor, the edge is uneven and has burrs or severe bending, the tip of the capacitor is prone to corona, and the corona will decompose the oil and expand the casing. The oil level drops and causes breakdown. In addition, when the cover is closed, if the welding time is too long at the corner, the internal insulation is burned and oil and gas are generated, so that the voltage is greatly reduced and the capacitor is damaged.
Poor sealing and oil leakage: due to poor sealing of the assembled casing, moisture enters the interior, which reduces the insulation resistance; or the oil level drops due to oil leakage, resulting in pole-to-shell discharge or component breakdown.
Drum and internal free: due to internal corona, breakdown discharge and internal free, the capacitor under the action of overvoltage, the initial free voltage of the component is reduced below the working electric field strength, thereby causing physical, chemical and electrical effects. The insulation is accelerated and aged, decomposed, and gas is generated to form a vicious cycle, which increases the pressure of the casing and causes the outer drum of the casing to explode.
Charged closing causes the capacitor to explode: the capacitor group of any rated voltage is prohibited from being charged. Each time the capacitor bank is reclosed, the capacitor must be discharged for 3 minutes with the switch open, otherwise the closing moment will cause an explosion due to residual charge on the capacitor. For this purpose, a capacitor bank with a capacity of 160 kvar or more is generally required. An automatic discharge device with no pressure should be installed, and the switch of the capacitor bank is not allowed to be installed with automatic closing.
In addition, capacitors may be damaged due to excessive temperature, poor ventilation, excessive operating voltage, excessive harmonic components, or overvoltage.
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