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Q1. With reference to the provision of a shore electrical supply to a ship:

A. Sketch an arrangement for taking A.C. shore supply and checks to be carried out prior taking shore connection?

B. Describe the method of safely connecting the arrangement sketched in (A) to the shore Supply?

Q2. With reference to U.M.S. operations:

A. State with reasons the essential requirements for unattended machinery spaces;

B. As second Engineer, describe how you would respond to the irretrievable failure of the Machinery space fire alarm system whilst the ship is on voyage.

Q3. Direct on line starting for large induction motors such as those for bow thrust units, may not   be viable. A. State the reasons for this; B. Sketch a starting system that may be used for such motors; C. Describe the starting method sketched in B.

Q4. A. In a.c. generators, voltage dip occurs in two stages.

I. Sketch a voltage-time graph showing the pattern of voltage dip.

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

B. Explain EACH of the following categories of voltage control:

(i) Error operated; (ii) Functional.

Q5. A. Which of the following devices will prevent a DC generator from becoming motorized? i. Over current relay; ii. Motorization trip; iii. Reverse power relay;  iv. Reverse current relay. B. Give a detailed explanations as to why other options were not considered.

Q5. A. Differentiate between series and parallel resonances. Draw impedance characteristics of these circuits. B. A 2,000-K VA, 3-phase, 8-pole alternator runs at 750 r.p.m in parallel with other machines on 6,000 V bus-bars. Find synchronizing power on full-load 0.8 p.f. lagging per mechanical degree of displacement and the corresponding synchronizing torque. The synchronous reactance is 6 ohms per phase.

Q7. A. Distinguish between power efficiency and all-day efficiency. Why is all-day efficiency considered more reasonable basis for comparison than ordinary efficiency? B. The no-load current of a transformer is 5.0 Amps, power factor 0.25 when supplied at 235 V, 50 Hz. Turns on the primary winding is 200. Calculate A. the maximum value of flux in the core, B. the core loss.

Q8. A. What is a commutator? Discuss its rectifying action in detail.

B. Calculate the e.m.f. generated by a 4-pole, wave wound armature having 40 slots with 18 conductors per slot when driven at 1000 r.p.m. The flux per pole is 0.015 wb.

Q9. A. Discuss different methods of speed control of a d.c. series motor by adjusting field ampere turns.

B. A 230 V, d.c. shunt motor runs at 1000 r.p.m and takes 5 amperes. The armature resistance of the motor is 0.025𝛀 and shunt field resistance is 230𝛀. Calculate the drop in speed when the motor is loaded and takes the line current of 41 amperes. Neglect armature reaction.