江蘇春晨電纜有限公司生產JE JEH電機引接線，

功率關系

Power relation

在任一瞬間，電壓瞬時值和電流瞬時值的乘積稱為瞬時功率，用符號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

瞬時功率公式

Instantaneous power formula

由上式可見，電阻的瞬時功率是隨時間變化的。它由兩部分組成，一部分為恒定量UI；另一部分是幅值為UI，頻率為2ω的余弦函數。p的曲線如上圖b所示。由于u、i相位相同，所以瞬時功率總是正值，即P≥0，這說明電阻總是消耗功率的，電阻元件總是從交流電源吸收電能轉換為其他形式的能量，這種轉換過程是不可逆的。

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.

由于瞬時功率隨時間不斷地進行周期性變化，在工程上應用很不方便。因此，取瞬時功率在一個周期內的平均值來表示交流電功率的大小，即稱為平均功率，用P表示。JE JEH電機引接線

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

由于平均功率是電阻實際消耗的功率，所以又稱為有功功率，單位為瓦（W）或千瓦（kW）。如電燈泡的額定功率是100W，說明它工作時消耗的有功功率是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.