DieselShip's Online Content Library

Q1. Explain the principle of operation of synchronous Motors with a simple sketch. Where are synchronous motor used onboard? (16)

Q2.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)

Q3. With reference to batteries onboard:

a) Distinguish between ‘Lead acid cell’ and ‘Alkaline cell’ (6)

b) Describe how a battery of alkaline cells may be tested for its usefulness, after a long storage and if found deficient, how it can be remedied? (6)

c) Explain how the ambient temperature is taken into account when determining the condition of the battery (4)

Q4. With reference to a three-phase shipboard electrical distribution system:

a) Enumerate the advantages of an insulted neutral system. (4)

b) Enumerate the disadvantages of an insulted neutral system. (4)

c) Describe how the Earthed neutral system is earthed. (4)

d) Compare the use of an insulated neutral system as opposed to the use of an Earthed neutral system with regard to the risk of electric shock from either system. (4)

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)

Q6. (a) The capacitor-start induction run motor has a much higher starting torque than the resistance split-phase motor. Explain (6)

(b) 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. (10)

Q7. A. Discuss the rights and expectations of seafarers in relation to occupational safety as per maritime labour conventions. (8)

B. What are the steps taken to reduce discrimination among seafarers due to differences in age, gender, language, nationality, and culture. (8)

Q8. With reference to a lifeboat gravity davit arrangement:

A. Sketch the arrangement showing the lifeboat both in the housed position and at its maximum point of outboard travel. (8)

B. Describe the lowering and raising of life boat stating the safety features and the requirement as per SOLAS 74, with respect to time for hoisting. (8)

Q9. a) Explain the factors that are considered in the development of critical equipment and systems onboard ship as per ISM code. (8)

b) Give your opinion on the importance of identifying critical equipment and systems onboard ship. (8)