翻译P.1The voltage across a pure inductor is defined by Faradaylaw,which states that the voltage across the inductor is proportional to the rate of change with time of the current through the inductor.thus we have U=Ldi/dt.纯电感电压由法拉第定律定义，法拉第定律指出：电感两端的电压正比于流过电感的电流随时间的变化率。因此可得到：U=Ldi/dt 式中 di/dt = 电流变化率， 安培/秒； L = 感应系数， 享利。P.3A three-phase electric circuit is energized by three alternating emfs of the same frequency and differing in time phase by 120 electrical degrees .三相电压的产生三相电路可由三个频率
