DieselShip's Online Content Library

Q1. a) What are safety incorporated in ACB of ship’s generator and prime mover? (10)

b) Explain the procedure to test reverse power relay (6)

Q2. a) What are the advantages and disadvantages of Neutral insulated system. (6)

b) An Alternator does not build up any voltage after start. Describe step by step procedure to solve the problem for all reasons. (10)

Q3. (a) Draw circuit diagram and explain working of Star – Delta starter. (8)

(b) Explain with diagram how direction of single phase induction motor is reversed. (8)

Q4. a) Why is it important to maintain high efficiency of operation? And low values of voltages regulation for power transformers? (6)

b) A shunt motor supplied at 230 V runs at 900 rpm. When the armature current is 30 A, the resistance of the armature circuit is 0.4 Ω. Calculate the resistance required in series with the armature circuit to reduce the speed to 500 rpm. Assume that the armature current is 25 Amps. (10)

Q5. a) What is back emf? Derive the relation for the back emf and the supplied voltage in terms of armature resistance (6)

b) The earth-lamps on a main switchboard comprise two 240V 60W lamps connected in the usual manner. The potential difference at the busbars is 220V. Damage by sea water occurs to a distribution cable so that the insulation resistance to the earth is reduced to 16 ohms and 6 ohms for +ve and -ve cables respectively. Find by calculation:

a) Which of the two lamps burns the brighter; and

b) The additional load on the generators occasioned by the fault. The resistance of the cables and the ship’s structure may be neglected, and that of the lamps taken as constant at the value corresponding to the 60W rating. (10)

Q6. A coil of inductance 2 H and unknown resistance is connected to a D.C. supply of 100 volts. After 4 ms the current has risen to 75% of its final steady state value. Calculate EACH of the following:

(a) The resistance by the coil. (6)

(b) The energy stored in the coil when the current has reached its steady state value. (6)

(c) The time taken for the current to fall to 50% of its steady state value when the supply is switched off. (4)

Q7. a) Describe CO2 Fixed fire fighting system for machinery spaces and cargo spaces of a bulk carrier. (8)

b) Explain safety precautions taken prior to release of CO2 to the engine room. (8)

Q8. a) Sketch and describe hydraulic circuit of steering gear incorporating automatic isolation system. (8)

b) Explain ‘Emergency steering’ (4)

c) Describe the routine tests of steering gear as per SOLAS requirement. (4)

Q9. (a) (i) With respect to the hazardous areas of tankers, explain the term flameproof (Exd) for electrical equipment. (6)
(ii) State the type of electrical equipment that would be protected in this way. (4)
(b) List likely defects of flameproof equipment. (6)