第一图即为用于交流电源的半波无触点开关,当阳极对阴极为正主时,使 SCR 导通的控制极电流是由主交流电源取得的简单方法。SCR 导通的当时,恰是使它导通时所需阴极电压的电压值,这时控制极电流减少。电阻值限制了控制极电流的峰值。控制极回路的整流二极管的作用是在阳极电压为负时,不使阴极和控制极之间加以反向电压。 The first figure is a half-wave contactless switch for AC power. When the anode-to-cathode is positive, the gate current that turns the SCR on is a simple method taken by the main AC power source. SCR conduction at that time, it is the cathode voltage when it is required to turn on the voltage value, then reduce the control pole current. The resistance limits the peak of the pole current. The function of the rectifier diode of the control loop is to prevent reverse voltage between the cathode and the control electrode when the anode voltage is negative.