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Q1. a) State essential electrical services on board that are able to be operable under fire conditions. (5)

b) Explain how electric cables for the essential services in part (a) pass through bulkheads whilst maintaining gas tight and watertight integrity. (5)

c) State the requirements for the cables which supply electrically driven emergency fire pumps. (6)

Q2. a) Sketch a circuit diagram of a push button direct online contactor starter for a three phase Incorporating overload and short circuit protection. (8)

b) Indicate, on a sketch of the typical characteristic curves of current and torque against Speed, disadvantages of a direct online start squirrel cage induction motor. (8)

Q1. Differentiate between half and full wave rectification. State where half wave rectification may be used and the purpose for which it is not well adapted. Sketch a bridge connection by which full wave rectification may be obtained. (16)

Q4. a) What design factor limits the maximum torque of a d.c. motor? (6)

(b) A shunt motor runs on no load at 700 r/min off a 440 V supply. The resistance of the shunt circuit is 240Ω. The following table gives the relationship between the flux and the shunt current:

Shunt current (A):      0.5   0.75   1.0   1.25   1.5   1.75   2.0

Flux per pole (mWb): 6.0   8.0   9.4   10.2   10.8   11.2   11.5

Calculate the additional resistance required in the shunt circuit to raise the no-load speed to 1000r/min (10)

Q5. (a) On what factors does the capacitance of a parallel-plate capacitor depend? (6)

(b) A tuned circuit consisting of a coil having an inductance of 200µH and a resistance of 20Ω in parallel with a variable capacitor is connected in series with a resistor of 8000Ω across a 60 V supply having a frequency of 1 MHz. Calculate: (10)

(a) The value of C to give resonance.

(b) The dynamic impedance and the Q factor of the tuned circuit.

(c) The current in each branch

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

(b) An eight-pole armature is wound with 480 conductors. The magnetic flux and the speed are such that the average e.m.f. generated in each conductor is 2.2 V, and each conductor is capable of carrying a full load current of 100 A. Calculate the terminal voltage on no load, the output current on full load and the total power generated on full load when the armature is:

(i) Lap connected

(ii) Wave connected (10)

Q7. Explain the cargo hold fire detection system used on ships. Discuss the maintenance procedures for this system and outline the steps taken when a fire is detected in the cargo hold. (16)

Q8. Discuss the following with respect to international safety Management (ISM) Code: (16)

a) Management Review and its agenda

b) Functional requirement and objectives of code.

c) Master responsibility and Authority.

d) Certification and periodical verification.

Q9. Briefly discuss the following with respect to safety of navigation:

a) Bridge Navigation Watchkeeping Alarm System (BNWAS) (6)

b) Long Range Identification and Tracking of ships (LRIT). (5)

c) Voyage Simplified Voyage Recorder (VDR/S-VDR) (5)