A step down chopper is operated in the continuous conduction mode in steady state with a constant duty ratio $$D.$$ If $${V_0}$$ is the magnitude of the $$dc$$ output voltage and if $${V_s}$$ is the magnitude of the $$dc$$ input voltage, the ratio $${{{V_0}} \over {{V_s}}}$$ is given by

A six pulse thyristor rectifier bridge is connected to a balanced $$50Hz$$ three phase $$ac$$ source. Assuming that the $$dc$$ output current of the rectifier is constant, the lowest frequency harmonic component in the $$ac$$ source line current is

In the single phase diode bridge rectifier shown in fig, the load resistor is
$$R = 50\Omega .$$ The source voltage is
$$V = 200sin\omega t,$$
Where $$\omega = 2\pi \times 50$$ radians per second. The power dissipated in the load resistor $$R$$ is

A three phase thyristor bridge rectifier is used in a $$HVDC$$ link. The firing angle $$\alpha $$ (as measured from the point of natural commutation) is constrained to lie between $${5^ \circ }$$ and $${30^ \circ }$$. If the $$dc$$ side current and $$ac$$ side voltage magnitude are constant, which of the following statements is true (neglect harmonics in the $$ac$$ side current and commutation overlap in your analysis)