Requirements Of Safety Capacitors For Electrical Flow Rate And Working Voltage During Operation

Safety capacitors are one of the indispensable capacitors in people's daily lives, and they are used in power circuits. Not long ago, an online editor received a customer's question, "I want to buy an incorrect safety capacitor. The breakdown voltage of the capacitor is different from that of the power circuit. Can it be used?" I think it is not possible, as working voltage and current can cause harm to the capacitor.

Requirements of safety capacitors for electrical flow rate and working voltage during operation

If the working voltage is only slightly higher, it can be applied, but it cannot be too high. Safe capacitors are very flexible in changing the working voltage. Prolonged overvoltage can cause the capacitor to become severely scalded, accelerate the embrittlement of the insulation layer, reduce its service life, and even result in electric or thermal breakdown. The working voltage of the power grid should usually be less than the rated current of the capacitor itself, and the long-term DC steady-state overvoltage should not exceed 1.2 times the rated current. Therefore, parallel capacitor equipment should operate at the rated current, which is usually not suitable for exceeding 1.05 times the rated current. The operating working voltage should not exceed 1.2 times the rated current.

If the current level is only slightly higher, it can be applied, but it cannot be too high. When the safety capacitor operates on the power grid of machine equipment with iron core saturation, high-order harmonics will appear during operation. For n-order harmonics, the reactance of the capacitor will be 1/n of the fundamental wave, so the harmonic current will be more significantly increased. Harmonic current is very harmful to capacitors, and it is most likely to cause thermal breakdown due to overheating. Considering the existence of harmonics, it is required that the electrical flow of the capacitor during operation should not exceed 1.7 times the rated voltage. If necessary, an appropriate reactance (series reactor) should be connected to the capacitor in series to suppress harmonic current.

The current and voltage during the operation of safety capacitors should still comply with their rated voltage and working voltage, so that they can operate smoothly.