Voltage is one of the most important indicators in the field of electric energy quality. Once there is voltage deviation, it will not only have a negative impact on related electrical equipment, but also may affect the safety and stability of the entire system equipment when serious.

Therefore, it is essential to properly select the rated voltage of self-healing parallel capacitors. In today's article, we mainly analyze the consequences of capacitor voltage deviation, come and have a look!

How does voltage deviation affect capacitors?

It is known that the reactive power that self-healing shunt capacitors can provide is equal to the ratio of capacitor voltage to capacitor reactance, so it can be deduced that:

1. The reactive power of the capacitor is proportional to its voltage. Once the voltage of the capacitor is too low or in a downward trend, the reactive power provided by the capacitor to the grid will decrease, which will directly affect the overall effect of reactive power compensation.

In addition, if the voltage of the self-healing shunt capacitor is too low, it is easy to cause overvoltage operation of the capacitor, which may cause partial discharge of the capacitor and accelerate insulation aging.

2. If the rated voltage of the self-healing shunt capacitor is selected too high, it will also affect the actual service life of the capacitor, and will also cause a certain amount of waste of resources and investment.

Factors Affecting the Selection of Capacitor

Rated Voltage

The factors affecting the selection of the rated voltage of self-healing shunt capacitors in daily selection are roughly divided into two categories: one is that the voltage at the connection point will increase after the capacitor is connected to the grid; the other is that the capacitor terminal voltage will rise after the capacitor is connected in series. high .

Therefore, for pure capacitance compensation, the rated voltage of the shunt capacitor must be slightly higher than the system voltage. For example, in a 380V power system, the line voltage may be around 400V. In order to ensure the safe and stable operation of the capacitor, Xiaoku does not recommend directly selecting a 400V capacitor. It is recommended to use a self-healing shunt capacitor with a rated voltage of 440V.

If capacitive reactance is used together, it is necessary to properly select the capacitor voltage level according to the situation of the reactor. Common collocations are: 480V capacitor with 7% reactor, 525V capacitor with 14% reactor.