Q10. A. Write shorts notes on various types of DC Motors.
B. A 440V shunt motor takes an armature current of 30A at 700 rev/min. The armature resistance is 0.7ohm. If the flux is suddenly reduced by 20 per cent, to what value will the armature current rise momentarily? Assuming unchanged resisting torque to motion, what will be the new steady values of speed and armature current? Sketch graphs showing armature current and speed as functions of time during the transition from initial to final, steady-state conditions.
Q1. With reference to the provision of a shore electrical supply to a ship:
A. Sketch an arrangement for taking A.C. shore supply and checks to be carried out prior taking shore connection?
B. Describe the method of safely connecting the arrangement sketched in (A) to the shore Supply?
Q9. A. Explain the potential hazards if liquid-cooled transformers are used.
B. What are the losses in transformers? Mention the various factors which affect these losses. In a 25 KVA, 3300/233 V, single phase transformer, the iron and full-load Cu. Losses are respectively 350 and 400 watts. Calculate the efficiency at half-full load, 0.8 power factor
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