The L-C circuit shown in the figure has an inductance $$L=1mH$$ and a capacitance $$C = 10\mu F.$$

The $$L$$-$$C$$ circuit $$Q.13$$ is used to commutate a thyristor, which is initially carrying a current of $$5A$$ as shown in the figure below. The values and initial conditions of $$L$$ and $$C$$ are the same as in $$Q.13.$$ The switch is closed at $$t = 0.$$ If the forward drop is negligible, the time taken for the device to turn off is

Consider a three-phase, $$50Hz,$$ $$11$$ $$kV$$ distribution system. Each of the conductors is suspended by an insulator string having two identical porcelain insulators. The self capacitance of the insulator is $$5$$ times the shunt capacitance between the link an the ground, as shown in the figure. The voltage across the two insulators are

The zero-sequence circuit of the three phase transformer shown in the figure is

A three-phase, $$33$$ kV oil circuit breaker is rated $$1200$$ A, $$2000$$ MVA, $$3$$s. The symmetrical breaking current is