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Q1. (a) With the aid of a circuit diagram explain the working of Bridge rectifier. (8)

(b) Compare the performance of Bridge rectifier with Full wave and Half wave rectifier. (8)

Q2. (a) Explain, with the aid of a sketch, the principle of operation of an earth leakage detection system. (8)

(b) Explain why an insulated neutral system is used extensively on-board ships. (4)

(c) State, with reasons, why a single earth fault on an insulated neutral system should always be cleared as soon as possible (4)

Q3. (a) State FIVE essential electrical services that should be operable under fire conditions. (8) (b) Explain how electric cables for the essential services in part (a) pass through bulkheads whilst maintaining gas tight and watertight integrity. (4)

(c) State the requirements for the cables which supply electrically driven emergency fire pumps. (4)

Q4. (a) Name at least three types of temperature sensing devices for remote indication. (4)

(b) Explain the working of a Thermocouple type temperature sensor. (8)

(c) What are various materials used in a thermocouple? (4)

Q5. (a) What are the hazards associated with batteries? (4)

(b) What safety precautions are to be taken while operating and maintaining the batteries including in battery room. (6)

(c) What are the safety arrangements seen in the Battery room of a ship? (6)

Q6. (a) How does a moving coil ammeter measure large current (6)

(b) A moving coil instrument with a coil resistance of 1.98Ω, produces full scale deflection from a current of 10mA. Determine the value of shunt required to extend the range up to 10A. (10)

Q7. (a) Explain power factor with A.C. Sine wave and phasor diagram. (6)

(b) A circuit has a resistance value of 25Ω and an inductance value of 0.3H. If it is connected to a 230V, 50Hz supply, find the circuit current, the power factor and the power dissipation. (10)

Q8. (a) Compare Direct current with Alternating current. (6)

(b) A four-pole generator has a flux of 12 mWb/pole. Calculate the value of e.m.f. generated in one of the armature conductors, if the armature is driven at 900 rev/min. (10)

Q9. (a) Shunt generators having drooping characteristics are best suited for parallel operation. Discuss (6)

(b) Two 220 V D.C. generators each having linear external characteristics, operated in parallel. One machine has a terminal voltage of 270 V, on no-load and 220 V at a load current of 35 A, while the other has a voltage of 280 V at no-load and 220 V at 50 A. Calculate the output current of each machine and the bus bar voltage when the total load is 60 A. What is the kW output of each machine under this condition. (10)