DieselShip's Online Content Library

Q1. Differentiate between squirrel cage and wound rotor motors, of the three phase A.C. induction type, in respect of the following: (16)

(a) Rotor construction

(b) Torque characteristics

(c) Speed variation

Q2. If the motor terminal markings are unknown how would you identify the start, run and common terminal connections. (16)

Q3. (a) Sketch and describe the working of a Lead-Acid battery. (12)

(b) What routine maintenance is carried out on these batteries? (4)

Q4. Draw the wiring diagram of a fluorescent tube lighting and explain the function of choke, starter, condenser, across starter. What is the purpose of the coating inside of the tube with fluorescent powder? (16)

Q5. a) How protection is provided for electrical short circuit. (4)

b) Describe the construction and operation of HRC fuses. (8)

c) What are the advantages of HRC fuses. (4)

Q6. (a) Explain Kirchhoff’s current law (6)

(b) In the given circuit, find the current value I2 (10)

Q7. (a) Compare constant current method and constant voltage method of charging batteries. (6)

(b) The filament of a 230V lamp takes a current of 0.261A when working at its normal temperature 2000°C. The temperature coefficient of the tungsten filament material can be taken as 0.005°C⁻¹ at 0°C. Find the appropriate current which flows at the instant of switching on the supply to the cold lamp, which can be considered to be at a room temperature of 20°C. (10)

Q8. (a) Define work, Power and Efficiency (6)

(b) A shunt motor has an armature resistance of 0.2 ohms and with an armature current of 120 amperes runs at 750 r.p.m. off a 400-volt supply. Calculate the speed and armature current of the motor if the flux per pole is reduced to 75 per cent of its initial value, the total torque remaining unaltered. (10)