Improper temperature and voltage effects on film capacitors (1)

It is believed that a person who frequently touches the capacitor will clearly see that when the capacitor bank is broken, if a circuit breaker breaks down, a circuit will appear in the circuit, and several times overvoltage will appear on the terminals of the capacitor. Under such a high operation overvoltage, a strong partial discharge and dielectric damage occur inside the film capacitor, and even cause the capacitor to break down. The quality of the circuit breaker used to switch the capacitor is therefore closely related to the actual lifetime of the capacitor. In order to prevent excessive inrush current and over-voltage, capacitors should be discharged in time when the capacitor is withdrawn from the network. The residual voltage on the capacitor should not exceed 10% of its rated voltage before putting the capacitor into operation in the grid again.

The service life of a film capacitor is related to the ambient temperature:

Each capacitor's tag is marked with its temperature category, for example: "-40/A", which means that this capacitor can be put into operation at a low ambient temperature of -40 °C. The high ambient temperatures that this capacitor can run continuously are: Ih average high temperature is 40°C, 24h average high temperature is 30°C, and annual average high temperature is 20°C. This is because at low temperatures, the viscosity of the impregnating agent inside the capacitor increases, the internal voltage decreases, and the capacity of the capacitor to withstand electricity decreases.