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)
Q1.a) Explain three methods of overcurrent protection for electrical circuit. (8)
b) Explain with aid of diagram, the meaning of the term inverse current time characteristic (8)
Q1. What are semiconductor devices? What are its advantages over thermionic devices? With respect to semiconductor devices describe working principle and application of the following: (16)
(a) Zener Diode
(b) Transistor
(c) Photocell
(d) Thyristor
Q5. a) Describe the different type of losses occurring in the Power Transformers. (4)
b) A single-phase power transformer supplied a load of 20 KVA at a P.F of 0.81 (lagging). The iron loss of the transformer is 200 W and the copper loss at this load is 180 W. Calculate
(i) The efficiency
(ii) If the load is now changed to 30 KVA at a p.f of 0.91 (lagging). Calculate the new efficiency
Q9. Briefly discuss the following with respect to safety of navigation:
a) Bridge Navigation Watchkeeping Alarm System (BNWAS) (6)
b) Long Range Identification and Tracking of ships (LRIT). (5)
c) Voyage Simplified Voyage Recorder (VDR/S-VDR) (5)
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