Safety capacitors for operating current and voltage requirements

Safety capacitors are also one of the essential capacitors in our lives and are widely used in circuits. Recently, the editor received a customer and asked, "I bought the wrong safety capacitor. The voltage resistance of the capacitor and the withstand voltage of the circuit are different. Can I use it?" I think it is impossible to edit, voltage and current will produce capacitors. Affected.

The voltage can be used if it is only a little higher, but it can't be too high. Safety capacitors are very sensitive to voltage changes. Long-term overvoltages can cause severe heat generation in capacitors. Capacitor insulation can accelerate aging, life is shortened, and even electrical breakdown or thermal breakdown occurs. The grid voltage should generally be lower than the rated voltage of the capacitor itself. The long-term power-frequency steady-state over-voltage should not exceed 1.1 times the rated voltage. Therefore, the shunt capacitor device should operate at the rated voltage. Generally, it should not exceed 1.05 times the rated voltage. The operating voltage should not be Exceeding 1.1 times the rated voltage.

The current can be used if it is only a little higher, but it can't be too high. When the safety capacitor is operated on the grid of the equipment with saturation of the core, high harmonics will appear during operation. For the nth harmonic, the reactance of the capacitor will be 1/n of the fundamental, so the harmonic current Will increase significantly. Harmonic current is very harmful to the capacitor, and it is easy to cause breakdown of the capacitor due to heat generation. Considering the existence of harmonics, the working current of the capacitor must not exceed 1.3 times of the rated current. If necessary, the appropriate reactance should be connected in series with the capacitor (series reactance To suppress harmonic currents.

The current and voltage of the safety capacitor must be in accordance with its rated current and voltage in order to operate stably.