Q5. With Reference to different types of transformers used onboard.
a) Discuss the basic principle of operation of a transformer (5)
b) Enumerate the different types of transformers used onboard also state their functions for which they are used. (5)
c) A 440/110 V single phase transformer supplies a load of 5kW at 0.8 power factor load. Calculate the primary and secondary currents. (Ignoring transformer power losses)? (6)
Q3. a) Write a short note on the principle of operation of induction motors (8)
b) What is slip for an induction motor? (4)
c) If a 4-pole motor is supplied at 60Hz and runs with a slip of 5%. What is the actual rotor speed? (4)
Q2. With Respect to Insulated and Earthed Neutral Systems used on board:
a) Discuss the Advantages and Disadvantages of both Insulated and Earthed Systems used on board. (8)
b) Discuss the consequences of earth fault in an earthed distribution system. (4)
c) What would be the Ohmic value of the NER to limit the earth fault to the full load rating of a 2 MW, 0.8 pf, 3.3KV, 3Phase A.C. generator? (4)
Q5. Explain with the help of a neat diagram the operation of a brushless alternator. What would likely happen if one of the rotating Diode fails and becomes: (16)
a) An open circuit?
b) A short circuit?
Q1. With respect to generators and main circuit breakers and their protection devices:
a) What are safeties incorporated in Air circuit breaker (ACB) of ship’s generator and prime mover? (10)
b) Write Short Note on Negative phase Sequence Relay. (6)
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