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Q2. a) Describe the circuit breaker for an A.C. generator using a sketch to show how arcing is controlled. (8)

b) Explain the sequence of events that might occur if the breaker opens on a short circuit and state the check you would require following such event. (4)

c) Give a safe procedure to follow should a main circuit breaker fail to open under fault Condition. (4)

Q2. In a ship’s power system, the neutral on the low voltage side is not grounded, but it is mandatory to ground the neutral in high voltage systems. Discuss in detail for the above difference and with suitable sketches, explain the different earthing arrangements for HV system (16)

Q2. a) In A.C. generators, voltage dip occurs in two stages.

i) Sketch a voltages-time graph showing the pattern of voltage dip. (4)

ii) Referring to this graph, state the reasons the effect on the electrical system of a small power installation when a large load is suddenly switched on. (4)

b) Explain EACH of the following categories of voltage control:

i) Error operated (4)

ii) Functional (4)

Q4. (a) Why is a synchronous motor not self-starting? What are the various ways in which it can be started?

(b) Differentiate Ge and Si diode characteristics. The reverse bias saturation current for a P-N junction diode is 1.0 µA at 300 K. Determine its AC resistance at 150 mV Forward bias. (10)

Q5. a) Describe the no-load saturation characteristics of a D.C. generator. (6)

b) 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)

Q6. a) What is back emf? Derive the relation for the back emf and the supplied voltage in terms of armature reactance. (6)

b) Two earth lamps at 120 V, 15 W are used on a 110 V distribution circuit. Due to damage to a motor, the resistance of the positive line is reduced to 10 ohm and that of the negative line to 5 ohm. Find the voltage across each lamp and the extra load on the generator due to the fault. (10)

Q7. With reference to Annex V of MARPOL 73/78 that deals with the prevention of pollution of the sea by garbage from ships –

a) Define the following terms.

i) Garbage

ii) Nearest land

iii) Special areas (8)

b) State the regulations governing the disposal of garbage outside special areas. (8)

Q8. With reference to oil monitoring of effluent from oil tanker cargo discharge:
a) Describe with a sketch, the general arrangement of an oil discharge monitoring and control system. (8)
b) State the inputs that are recorded. (4)
c) Explain the difficulties encountered with the efficient operation of the oil monitoring system. (4)
- - - PREVIOUSLY ASKED - - -
With reference to oil monitoring of bilge and tanker ballast discharges:
a) Describe with the aid of a sketch, the general arrangement of an oil monitoring system. (8)
b) State the inputs that are recorded. (4)
c) Explain the difficulties encountered with the efficient operation of the oil monitoring system. (4)

Q9. Explain the principle of port State control and give in detail the verification , the Port State Control Officer may carry out with reference to the following:

a) Emergency generator (4)

b) Auxiliary steering gear (3)

c) Lifeboat engine (3)

d) Bilge pump (3)

e) SOPEP (3)