176. In a thyristors are i = kva. The value of a is
177. In an ordinary thyristor
178. Thyristors connected in series need :
179. If 4 quadrant operation is required we need
180. A single phase half wave converter is feeding a resistive load. Output dc power is Pdc and total power delivered to load is Pac then
181. Which of the following devices exhibit negative resistance characteristics?
182. In integral cycle control of ac regulators, the period of integral cycle control, i.e., (m + n) T should be
183. All other parameters remaining the same, a 3 phase bridge inverter with 180° mode of operation
184. As compared to BJT, MOSFET has
185. If a step down chopper is fed by a dc voltage V with Ton and Toff are on and off periods then is
186. A voltage VBB is applied across the terminals of a UJT. The emitter voltage at peak point is
187. A single phase bridge type cycloconverter uses eight thyristors.
188. In the circuit of figure, the waveshape of load current when thyristor conducting is
189. In the basic series inverter circuit, the source supplies load
190. A current source inverter has simple commutation circuit.
191. In load commutated chopper, the commutating element
192. In a half bridge inverter each thyristor is gated at a frequency f. The output frequency is
193. Assertion (A): A transistor has lower voltage drop during conduction as compared to thyristorReason (R): Transistors are manufactured in very high voltage and current ratings.
194. Assertion (A): Typical value of thermal resistance from source to sink of an SCR is about 0.3° C/WReason (R): Heat sinks of thyristors are generally made of aluminium.
195. Multiphase choppers are used in
196. In a single phase converter using a centre tapped transformer and with a highly inductive load, the firing angles is a . Each thyristor conducts for a period
197. A step up chopper can give an output voltage
198. The specified maximum junction temperature of thyristors is about
199. A bridge type single phase cycloconverter changes the frequency f to f/3. Then one half wave of output contains