Figure 1.a shows a single phase a.c. voltage controller with RL load.The waveforms for source voltage $E_{s},$ gate currents $i_{g_{1}}$ and $i_{g_{2}},$ load and source currents $i_{0}$ and $i_{s},$ load voltage $e_{0},$ and thyristor voltages are shown in Fig.1.b.

During the interval zero to $\pi$ , thyristor $T_{1}$ is forward …