In this topic, you study SCR as a Switch.
The power devices can be operated as static switches. If the supply to these switches is DC, the switches are called DC switches and if the supply given is AC, then the switches are termed AC switches. The SCR is particularly suitable for controlling the alternating currents. The following illustration will make this clear in which AC voltage V is applied to the thyristor anode circuit. It varies with time. By closing the switch S in the gate circuit momentarily as shown in Figure 1 (a), gate pulses against equal intervals of time are produced. Figure 1 (b) shows the waveform of the anode current against time. Anode current flows from the instant when the triggering pulse is applied to the zero crossing point of the applied AC voltage.
(a)
(b)
Fig. 1: (a) Circuit Diagram, (b) Waveforms of the anode current of a thyristor circuit
