江苏春晨电缆有限公司生产YCB橡套扁电缆 移动扁电缆，
f the average power is zero, it means that the capacitor does not consume active power, and it does not mean that there is no power in the capacitor. There is energy exchange between the capacitor and the power supply, so the instantaneous power is not equal to zero. The product of the maximum value UI of instantaneous power is called reactive power, which is represented by the symbol QC. It reflects the maximum scale of the exchange energy between the capacitor and the power supply.
电容的无功功率计算公式
Calculation formula of reactive power of capacitor
Qc的单位为乏（var）或千乏（kvar）。
The unit of QC is var or kvar.
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题：已知电容器的电容量C=10μF，现分别将它接在⑴直流220V电源上；(2)工频交流电压有效值220V电源上；(3)500Hz、220V交流电源上，求电容的电流I和无功功率Qc。
Title: given that the capacitance of the capacitor is C = 10 μ F, it is connected to (1) DC 220V power supply; (2) power frequency AC voltage effective value 220V power supply; (3) 500Hz, 220V AC power supply, the current I and reactive power QC of the capacitor are calculated.
解：(1)在直流220V电源上因为直流电压的频率f=0，所以容抗：
Solution: (1) on the DC 220V power supply, because the frequency of DC voltage f = 0, the capacitive reactance:
算式
Formula
由计算结果可知，电容对直流相当于开路；对高频电流阻抗小，电流易通过；对低频电流阻抗大，电流难通过。利用电容器的这种特性，可以将电容器制成滤波器YCB橡套扁电缆 移动扁电缆
It can be seen from the calculation results that capacitance is equivalent to open circuit for DC; small impedance for high frequency current, easy to pass current; large impedance for low frequency current, difficult to pass current. Using this characteristic of the capacitor, the capacitor can be made into a filter