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)
Q6. With reference to Diesel engine driven alternator:
a) Explain the significance of the term “speed droop” during the parallel operation of alternators. Assuming two alternators are running in parallel, outline the frequency vs load characteristics of the alternators while load sharing. (8)
b) Two 3Ø alternators operate in parallel, the rating of A is 1000 kW and B is 800 kW. The droop setting of each generator is 4%, If the load to be shared by both the generators is 1000 kw, calculate the load sharing by generators A and B, if the original frequency at no-load is 62Hz. (8)
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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