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Q2. a) Explain why it is necessary to have reverse power protection for alternators intended for operation. (6)

b) (i) Sketch a reverse power trip. (5)

(ii) Briefly explain the principle on which the operation of this power trip is based and how tripping is activated. (5)

Q2. A. Describe a brush less alternator with a.c. exciter static A.V.R. (8)
B. State the output voltage characteristics for this type of machine. (8)

Q3. Which of the following devices will prevent a DC generator from becoming motorized?

a) Over current relay

b) Motorization trip

c) Reverse power relay

d) Reverse current relay.

why the remaining options were not considered. (16)

Q4. a) What is a commutator? Discuss its rectifying action in detail. (6)
(b) Determine the line current taken by a 440 V, three-phase, star-connected motor having an output of 45 Kw at 0.88 (lagging) power factor and an efficiency of 93 per cent. (10)

Q5. a) Describe the effects of changes in speed, rotor current and torque as load is applied to an induction motor. How does the motor adjust its stator current with changes in mechanical load? (6)
b) A 20 KVA, 2000/220V, single-phase transformer has a primary resistance of 2.1 Ω and a secondary resistance of 0.026 Ω. The corresponding leakage reactance’s are 2.5 Ω and 0.03 Ω. Estimate the regulation at full load under power-factor conditions of:
(i) Unity

(ii) 0.5 (lagging)

(iii) 0.5 (Leading) (10)

Q6. a) Which of the following three motors has the poorest speed regulation: shunt motor, series Motor or cumulative compound motor? Explain. (6)
b) An 18.65 KW,4-pole,50HZ, 3 phase induction motor has friction and windage losses of 2.5 percent of the output. The full load slip is 4% compute for full load
(i) the rotor Cu loss
(ii) the rotor input
(iii) the shaft torque
(iv) the gross electromagnetic torque. (10)

Q7. Write reference to gravity lifeboat davits; state the purpose of the following:

a) Centrifugal brake.

b) Dead man’s handle.

c) Davit limit switch. (16)

Q8. In engine rooms that are operated under UMS conditions describe with the aid of sketches how the following are monitored: (8)
a) The perforation of a high-pressure fuel pipe.
b) Periodical maintenance checks and tests require to be done to verify the effectiveness of the above system. (8)

Q9. With reference to MARPOL Annex IV
a) Draw a biological sewage treatment plant and explain the principle of operation. (8)
b) Periodical maintenance and checks and tests required to be done to verify the effectiveness of the above system. (8)