江苏春晨电缆有限公司生产JE JEH电机引接线，
功率关系
Power relation
在任一瞬间，电压瞬时值和电流瞬时值的乘积称为瞬时功率，用符号p表示：
At any instant, the product of voltage instantaneous value and current instantaneous value is called instantaneous power, which is represented by symbol P
瞬时功率公式
Instantaneous power formula
由上式可见，电阻的瞬时功率是随时间变化的。它由两部分组成，一部分为恒定量UI；另一部分是幅值为UI，频率为2ω的余弦函数。p的曲线如上图b所示。由于u、i相位相同，所以瞬时功率总是正值，即P≥0，这说明电阻总是消耗功率的，电阻元件总是从交流电源吸收电能转换为其他形式的能量，这种转换过程是不可逆的。
It can be seen from the above formula that the instantaneous power of the resistor changes with time. It consists of two parts, one is constant UI, the other is cosine function with amplitude of UI and frequency of 2 ω. The curve of P is shown in Figure B above. Because the U and I phases are the same, the instantaneous power is always positive, i.e. P ≥ 0, which means that the resistance always consumes power, and the resistance element always absorbs electric energy from the AC power source and converts it into other forms of energy, which is irreversible.
由于瞬时功率随时间不断地进行周期性变化，在工程上应用很不方便。因此，取瞬时功率在一个周期内的平均值来表示交流电功率的大小，即称为平均功率，用P表示。JE JEH电机引接线
Because the instantaneous power changes periodically with time, it is inconvenient to apply in engineering. Therefore, the average value of instantaneous power in a cycle is taken to express the magnitude of AC power, that is, the average power, which is expressed by P.
平均功率公式
Average power formula
由于平均功率是电阻实际消耗的功率，所以又称为有功功率，单位为瓦（W）或千瓦（kW）。如电灯泡的额定功率是100W，说明它工作时消耗的有功功率是100W。
Because the average power is the power actually consumed by the resistor, it is also called the active power, and the unit is watt (W) or kilowatt (kw). If the rated power of the light bulb is 100W, it means that the active power consumed when it works is 100W.