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Q1. (a) Draw a 4-pole D.C. generator construction diagram labelling its main parts. (8)

(b) Describe briefly its (8)

(i) Field system

(ii) Armature

(iii) Commutator

(iv) Brushes

Q2. a) What are the safety devices provided on the steering gear system? (10)

b) What is the significance of the shaft hull earthing device on the shafting? (6)

Q3. a) Explain the working of a Megger with the aid of its internal circuit. (12)

b) What safety measures are taken while using a Megger? (4)

Q4. With the aid of a simple circuit diagram, explain the electrical distribution system for essential loads on board a cargo ship. (16)

Q1. (a) How busbar inspection and maintenance is carried out? (10)

(b) What are safety precautions taken while doing maintenance on the busbar? (6)

Q6. (a) Describe the basic principles of self-excited generators. (6)

(b) The armature resistance of a 200 V, shunt motor is 0.4 ohms. The no-load (this is the term used when the motor is running light, i.e. not loaded) armature current is 2A. When loaded and taking an armature current of 50 A, the speed is 1200 rev/min. Find the approximate no load speed.  (10)

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(b) The armature resistance of a 200 V, shunt motor is 0.4 ohms and the no-load armature current is 2A. When fully loaded and taking an armature current of 50 A, the speed is 1200 rev/min. Find the no-load speed and state the assumption made in the calculation. (10)

Q7. (a) Explain what is meant by phase difference between voltage and current values. (6)

(b) The open-circuit voltage of a cell as measured by a voltmeter of 100 ohm resistance, was 1.5 V, and the p.d. when supplying current to a 10 ohm resistance was 1.25 V, measured by the same voltmeter. Determine the e.m.f. and internal resistance of the cell. (10)

Q8. The loads of a 4-wire, 3-phase systems are:

Red line to neutral current = 50 A, power factor of 0.707 (lagging)

Yellow line to neutral current = 40 A, power factor of 0.866 (lagging)

Blue line to neutral current = 40 A, power factor 0.707 (leading).

Determine the value of the current in the neutral wire. (16)

Q9. (a) Describe the effect of running an induction motor on reduced voltage (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 on-load and 220V 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)