DieselShip's Online Content Library

Q1. a) What precautions must be taken when testing the insulation of generator cables and wiring connected to an AVR unit? (6)

b) How could you monitor the correct instant for synchronising, if synchroscope and synchronising lamps are not working? (6)

c) How the air gap of an alternator is measured and why the air gap of an alternator to be checked periodically? (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)

Q3. a) Explain with the aid of a diagram, a controller utilizing proportional plus integral action. (6)

b) List out the Advantages and Disadvantages of electric propulsion system (5)

c) Explain briefly what you know about “Pulse Width Modulation” and how it can be applied for propulsion control. (5)

Q4.a) Explain the construction and principle of operation of permanent magnet moving coil instrument. (8)

b) A permanent magnet moving coil instrument has a coil of dimension 15 mm × 12mm. The flux density in the air gap is 1.8 × 10-3 wb/m2 and the spring constant is 0.4 × 10-6 Nm / rad. Determine the number of turns required to produce an angular deflection of 900 when a current of 5 mA is flowing through the coil. (8)

Q5. A 400V, 4-pole, 50 Hz, 3-phase, 10 hp, star connected induction motor has a no load slip of 1% and full load slip of 4%, find the following:

(i) Syn speed

(ii) No -load speed

(iii) Full load speed

(iv) Frequency of rotor current at full load

(v) Full – load torque (16)

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)

Q7. a) Describe the routine tests required for self-contained breathing apparatus sets (8)

b) Describe the procedure to be adopted to find missing personnel in a smoke-filled accommodation area. (8)

Q9. With reference to an automatic water sprinkler, fire detecting alarm and extinguishing system for accommodation spaces:

a) Sketch a typical system. (4)

b) Describe the operation of this system. (4)

c) State the sources of water available. (2)

d) Describe the sprinkler head and its operation. (3)

e) State how the temperature rating of the sprinkler head is determined. (3)

Q9. With Respect to MARPOL, Annex V:

a) Explain the regulations stipulated for disposal of garbage under annex V of MARPOL 73/78. (8)

b) State the special areas notified under annex V of Marpol 73/78 (4)

c) State what precautions you will take during disposal of waste from Electrical workshop (4)