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Q4. It is proposed to operate a bow thruster’s unit from a 3.3 KV electrical supply outline suitable option for the design of installation under each of the following heading. Protection of main switch board Overload of a bow thrusters motor Cable protection.

Q2. Sketch a circuit diagram of an emergency generator power supply system suitable for passenger vessel: including in yours diagram the essential services supplied. With reference to an emergency generator stage - Its location; Methods of automatic starting; The time available for starting and connection of power to switchboard; Angles of heel and trim up to which it must be capable of operating; The length of time it must be cable of supplying emergency power

Q4. Explain the effect of reduced voltage on standard squirrel cage motors with respect to EACH of the following:

(i) Burn out; (ii) Starting current; (iii) Starting torque; (iv) Speed.

Q2. A. State the necessary conditions required prior to the synchronizing of electrical alternators.

B. Describe the type of cumulative damage that may be caused when alternators are incorrectly synchronized;

C. Explain how the damage referred to in (b) can be avoided / reduced.

D. For two alternators operating in parallel state the consequences of:

(i) Reduced torque from the prime mover of one machine.

(ii)Reduced excitation on one machine.

Q2. Sketch and describe an arrangement for automatic connection of emergency batteries upon loss of main power. Include in your answer:

A. Means of obtaining D.C. charging supply from a.c. mains;

B. A method of maintaining charge on lead acid batteries;

C. The arrangement to check that a battery operates a loss of main power

D. The length of time for which emergency batteries of passenger and cargo ships must provide power.

Q8. A. What is meant by negative and positive feed backs? Explain the characteristics of negative feedback; B. Compare the series and parallel resonance circuits. Find the frequency at which the following circuit resonates.

Q10.  (a). Describe the no-load saturation characteristic of a d.c. generator.

(b). A 4-pole machine running at 1500 r.p.m. has an armature with 80 slots and 6 conductors per pole. The flux per pole is 6 x 106 lines. Determine the terminal e.m.f. of d.c. generator if the coils are lap connected. If the current per conductor is 100 A, determine the electrical power.

Q8. A. What is slip? What are the factors on which the torque or an induction motor depends?  B) Calculate the pitch factors Kp for a wiping having 24 stator slots, 4 poles, when the coil span is 1 to 6

Q10. A. How does change to frequency affect the operation of the transformer? What makes this ratio different from the ratio of transformer? B. A 550 KVA, 50 Hz single phase transformer has 1875 and 75 turns in the primary and secondary windings respectively. If the secondary voltage is 220 V, calculate (i)Primary voltage; (ii)Primary and secondary currents; iii. Maximum value of flux.

Q7. A. Which of the following three motors has the poorest speed regulation: shunt motor, series Motor or cumulative compound motor? Explain.

B. A 440V shunt motor takes an armature current of 30A at 700 rev/min. The armature resistance is 0.7ohm. If the flux is suddenly reduced by 20 per cent, to what value will the armature current rise momentarily? Assuming unchanged resisting torque to motion, what will be the new steady values of speed and armature current? Sketch graphs showing armature current and speed as functions of time during the transition from initial to final, steady-state conditions.