High voltage capacitor voltage distribution

Capacitors are one of the most widely used electronic components in electronic equipment. They are widely used in the circuit of DC-blocking, coupling, bypass, filtering, tuning loop, control and so on. So what is the distribution of high voltage capacitors in the voltage?

If the internal components of the capacitor are in a parallel configuration, there is naturally no problem of a different voltage distribution. However, for capacitors whose internal components are connected in series, if DC and AC voltages are applied, the voltage distributed across the internal components will be different. When an alternating voltage is applied, an alternating current i is generated across the element, and the voltage u on each element is the product of i and its capacitive reactance: U = i * 1 / WC.

When a DC voltage is applied to the high voltage capacitor, a steady state DC leakage current is generated after the charge is saturated. The voltage of each component is the product of the resistance and the leakage current, that is, the voltage is distributed according to the insulation resistance value of the internal component. Generally speaking, in the manufacturing process of high-voltage capacitors, the error of the component value c of the internal series is very small, and the insulation resistance is greatly affected by the environment of the factory, and the individual error is correspondingly large. In other words, the voltage distribution according to the capacitance value c is an ideal test method.

When distributed according to the insulation resistance, the insulation resistance of the good component is relatively large, and the insulation resistance of the component subjected to most of the voltage problems is small, and only a small voltage is tolerated, which cannot guarantee the detection of the internal high-voltage electrical appliance. Therefore, it is generally believed that the DC withstand voltage test may cause an unreasonable voltage distribution of the internal series components relative to the AC withstand voltage test.