The Voltage Source Inverter $$(VSI)$$ shown in the figure below is switched to provide a $$50$$ $$Hz,$$ square-wave $$ac$$ output voltage ($${V_0}$$) across an $$R$$-$$L$$ load. Reference polarity of $${V_0}$$ and reference direction of the output current $${I_0}$$ are indicated in the figure. It is given that $$R = 3\,\,\Omega ,\,\,L = 9.55\,\,mH.$$

In the interval when $${V_0} < 0$$ and $${i_0} > 0$$ the pair of devices which conducts the load current is

A single load is supplied by a single voltage source. If the current flowing from the load to the source is $$10\angle - {150^0}$$ A and if the voltage at the load terminals is $$100\angle {60^0}$$ $$V,$$ then the

The angle $$\delta $$ in the swing equation of a synchronous generator is the

In the following network, the voltage magnitudes at all buses are equal to $$1$$ p.u., the voltage phase angles are very small, and the line resistance are negligible. All the line reactances are equal to $$j1\Omega .$$

The voltage phase angles in rad at buses $$2$$ and $$3$$ are