A single - phase full-bridge voltage source inverter feeds a purely inductive load, as shown in figure. when $${T_1},{T_2},\,\,\,\,\,{T_3},{T_4}$$ are power transistors and $${D_1},{D_2},\,{D_3},{D_4}$$ are feedback diodes. The inverter is operated in square-wave mode with a frequency of $$50$$ $$Hz.$$ If the average load current is zero, what is the time duration of conduction of each feedback diode in a cycle?

A half-wave thyristor converter supplies a purely inductive load, as shown in figure. If the triggering angle of the thyristor is $${120^ \circ }$$, the extinction angle will be

$$AC$$ to $$DC$$ circulating current dual converters are operated with the following relationship between their triggering angles $$\left( {{\alpha _1}} \right.$$ and $$\left. {{\alpha _2}} \right).$$

A $$50$$ Hz alternator is rated $$500$$ $$MVA,$$ $$20$$ $$kV,$$ with $${X_d} = 1.0$$ per unit and $$X'{'_d} = 0.2$$ per unit. It supplies a purely resistive load of $$400$$ $$MW$$ at $$20$$ $$kV.$$ The load is connected directly across the generator terminals when a symmetrical fault occurs at the load terminals. The initial rms current in the generator in per units is