DieselShip's Online Content Library

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. 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 6-pole motor is supplied at 60Hz and runs with a slip of 5%. What is the actual rotor speed? (4)

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)

Q5. a) Which has the greater equivalent resistance; two equal capacitors in series or in parallel? Explain with reasons? (6)

b) A circuit has a resistance of 3Ω inductance of 0.01H. The voltage across its end is 60V and the frequency is 50Hz. Calculate

a) the impedance

b) the power factor

c) the power absorbed. (10)

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?

Q6. A 100 KVA, 2400/240 V, 50 Hz, 1-phase transformer has no- load current of 0.64 A and a core loss of 700 W, when its high voltage side is energized at rated voltage and frequency . calculate the two components of no-load current. If this transformer supplies a load current of 40 amp at 0.8 lagging power factor at its low voltage side, determine the primary current and its power factor. Ignore leakage impedance drop. (16)

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)

Q7. With reference to entry into enclosed spaces onboard:
a) Define “Enclosed space” and give example of enclosed spaces onboard (6)
b) Describe the checks done for testing the atmosphere inside such enclosed spaces. (5)

c) Explain safety precautions taken prior to entry into enclosed spaces onboard vessel. (5)

Q9. With respect to the hazardous areas of tankers.
(a) Explain the term flameproof (Ex d) for electrical equipment. (6)
(b) State the type of electrical equipment that would be protected in this way. (5)
(c) List likely defects of flameproof equipment. (5)