Part-A(Objective Test Items) July 2008
Q:1. There are different shape of earth electrodes like pipe, plate, rod and grid.
Which shape of earth electrode used in generating plant?
Asn:1. Plate.
Q:2. After replacing the defective capacitor, the fan motor is still running slow at rated voltage. Bearing
and fan blades are found in good conductor.
What could be the reason for the above defect?
Ans:2. Fault in windings.
Q:3. In which unit AC voltage for long distance transmissions measured as per IE rules?
Ans:3. KV.
Q:4. Figure illustrated is for a typical field tapping method of speed control for a universal motor.
In which position of the switch the speed will be
a) High (full speed) b) Low
Ans:4. a) Position A for high speed.
b) Position C for low speed.
Q:5. When the tube light switch is "NO", the filaments of the tube at ends light, but the full illumination
is not taking place ,When a person keep his to hands at the ends of tube and moves the hand
to the center the tube fully.
The reasons for such defect are low supply voltage, defective starter and ............
Give two more reasons.
Ans:5. Weak active material due to aging, loose contacts, week filament and choke is partially shorted.
Q:6. Sometimes you see the disc of an energy meter rotating slowly though there is no load
while its pressure coil is energised.
One of the reason for this slow rotation is over compensation for friction.
Mention two more reasons.
Ans:6. a) Grouping error is due to the breaking magnet not properly adjusted.
b) Alignment of disc between the pins.
Q:7. Before commissioning any new electric appliances four tests should be performed.
Continuity of the element and test for supply.
State the other two tests.
Ans:7. a) Insulation resistance test.
b) Earth continuity test.
Q:8. State the possibilities for a change in the polarity of the terminal voltage of a DC generator?
Ans:8. a) Change in direction of rotation of prime mover.
b) Change in the direction of the field current.
Q:9. In a DC relay when the coil is energized it actuates the relay contacts.
What is the effect on the relay function if the polarity of supply to the relay coil is changed?
Ans:9. Relay functions normally (polarity reversal of supply has no effect on the function of the relay )
Q:10. Starters are needed for switching on DC motor because of the high starting current.
State two reasons for the high starting current
Ans:10. Back emf zero and the resistance of the armature is very small.
Q:11.You have to measure the current drawn by an induction motor without interrupting the circuit.
a) What instrument will you use ?
b) State the principle on which it works?
Ans:11. a) Clamp on meter or tong Tester.
b) Mutual induction.
Q:12. For terminating a cable in to screw on terminals the conductor should be looped.
What is the tool used for looping the conductor ?
In what direction the loop should be placed in to the screw for termination?
Ans:12. a) Round rose plier. b) Screw tight direction .
Q:13. a) Line voltage in a 3 phase system is referred to the voltage measured between..........
b)In which type of connection line voltage is equal to phase voltage.
Ans:13. a) Between two phase.
b) Delta connection.
Q:14. A 200 V, 2 KW DC motor has an efficiency of 0.8 at full load.
Ans:14. Motor output at full load =2000 W
n=80%
Input = output/efficiency x 100 = 2000/80 x 100 =2500 W
Current = W/V = 2500/200 = 12.5 A
Q:15. The speed of squirrel in DOL starter may be due to improper voltage , dirty pole faces and
defective spring in the NVC housing. You find all the above conditions are ideal and still the
problem persists.
What could be the other possible reason?
Ans:15. No change in speed even load varies.
Q:16. Chattering noise in DOL starter may be due to improper voltage,dirty pole faces and defective
spring in the NVC housing. You find all the above condition are ideal and still the problem persist.
What could be the other possible reason?
Ans:16. Broken pole shading ring.
Q:17. The small voltage fluctuation in the output of the rectifier is called ripple.
What is the ripple frequency of full wave rectifier?
Ans:17. 2f input.
Q:18. a) What is the purpose of transformers in regulated power supplies?
b) On what factor the output current regulated power supplies depend?
Ans:18. a)Stepping down AC voltage to the required AC voltage.
b) Load regulation.
Q:19. Universal motor control circuit is shown in the figure.
a) What is the function of the resistor R?
b) What are the consequences of a high and low value of resistance R with respect to speed
of the motor?
Ans:19. a) It varies the supply.
b) High value of resistance-slow speed
Low value of resistance- High speed
Q:20. Opening the switch of an inductive circuit sets an arc across the switch contacts due to large
voltage induced and stored energy magnetic field.
The arc is suppressed in such circuits by connecting........
A) a capacitor across the supply.
B) a capacitor across the switch contacts.
C) arcing horns across the switch contacts.
D) another small inductor across the switch contacts in reverse direction
Ans:20. B) a capacitor across the switch contacts.
Q:21. Every appliance should be tested for insulation resistance before commissioning. For a water
heater the insulation resistance should not be less than..........
A) 1 Meg ohm
B) 2 Meg ohm
C) 0.5 Meg ohm.
D) 0.25 Meg ohm
Ans:21. A) 1 Meg ohm.
Q:22. As a precautionary measure the heating element used in heaters, electric iron and water heaters
should not attain a temperature more than......
A) 335 degree
B) 635 degree.
C) 735 degree.
D) 1035 degree.
Ans:22. D) 1035 degree
Q:23. When a house wife accidently touched the metal part of the handle of a kettle. Which was
kept 'on'. She received an electric shock.
The reason is........
A) The fuse wire in the circuit is of higher capacity
B) The kettle is not earthed
C)There is no water in the kettle
D) The safety plug has become defective.
Ans:23. B) The kettle is not earthed
Q:24. What is the value of resistor in the circuit shown and its power rating you would select
for this function?
A) 2 W, 3.2 k ohm
B) 2 W, 6.4 K ohm
C) 4 W, 3.2 K ohm
D) 4 W, 6.4 K ohm
Ans:24. D) 4 W, 6.4 K ohm.
Q:25. Tong tester is used to measure the current in AC circuit without interrupting the circuit.
For measurement the split core is clamped on to the insulated current carrying conductor.
Looping of conductor passing through the split core is used some times.
What will be the reading for a selected range if the conductor is looped (double pass)?
A) Double the current which pass through the conductor.
B) 4 times (i.e., 22) the current which pass through the conductor.
C) Half the current which pass through the conductor.
D) Same as the conductor current.
Ans:25. A) Double the current which pass through the conductor.
Q:26. The direction of rotation of a permanent capacitor motor can be reversed by interchanging the ......
A) Centrifugal switch terminals
B) Auxiliary winding terminals
C) Capacitor terminals
D) Supply terminals
Ans:26. B) Auxiliary winding terminals.
Q:27. Which type of fault is tested in the above figure?
A) Testing the continuity of each winding.
B) Testing for open circuits.
C) Testing for grounds.
D) Testing the resistance value between each winding.
Ans:27. C) Testing for grounds.
Q:28. You have to change the defective induction motor of a machine. The available motor is of a
higher capacity than the existing one.
What is the effect of using a higher capacity motor?
A) The new motor will be overheated.
B) The new motor is better suitable for this work.
C) The efficiency and the power factor will become low.
D) The new motor has a longer useful working life and efficiency.
Ans:28. C) The efficiency and the power factor will become low.
Q:29. Brush tension in a DC generator play very important role in its performance.
Excessive brush tension may.........
A) Slow down the speed of the machine
B) Decrease the output voltage
C) Increase the output voltage
D) Overheat the commutator and wear out the surface.
Ans:29. D) Overheat the commutator and wear out the surface.
Q:30. What are the ON / OFF terminals of a transistor when it is operated as a switch?
A) Collector to base
B) Collector to emitter
C) Base to collector
D) Emitter to base.
Ans:30. B) Collector to emitter
Q:31. Which colour wire is recommended for earth connection as per ISI code?
A) Red
B) Green
C) Black
D) Blue
Ans:31. B) Green
Q:32. If single phasing occurs during running of a 3 phase motor, What is the effect on motor
performance?
A) Motor will run as 2 phase motor and performs normally.
B) Will continue to run on 2 phases but fails to take load.
C) Continue to run on 2 phases, draws excess current,winding likely to burn.
D) Run at reduced sspeed and can take only 2/3 of the load
Ans:32. C) Continue to run on 2 phases, draws excess current,winding likely to burn.
Q:33. The precision of measurement depends on the range of the instrument selected.
What is the general rule for selection of range of instrument?
Measured value should be.........
A) Above the mid-scale
B) Below the mid-scale
C) On the mid-scale
D) Exactly on full scale
Ans:33. A) Above the mid-scale.
Q:34. Rotor resistance starters are used with wound rotor induction motor,
When the motor is running the resistance in starter are........
A) Shorted
B) Open circuited
C) Connected in delta
D) Connected in star
Ans:34. A) Shorted
Q:35. How the PF meter is connected in the motor circuit?
A) Fixed coil in parallel with the supply and moving coil in series with single phase motor.
B) Fixed coil across the motor and moving coil across the supply.
C) Fixed coil in series with motor and moving coil across the supply.
D) Both Fixed coil and moving coil in series with the motor.
Ans:35. A) Fixed coil in parallel with the supply and moving coil in series with single phase motor.
Q:36. You have to change the defective motor of an electric locomotive.
Which type of motor would you choose?
A) DC differential compound motor.
B) DC shunt motor.
C) DC series motor.
D) Separately excited motor.
Ans:36. C) DC series motor.
Q:37. Match the materials with the parts of U.G cable
Materials
1) Copper
2) Lead (or) Lead Alloy
3) Steel wire
4) Aluminium
Parts of Underground cable
A) Core
B) Metallic sheath
C) Armouring
Ans:37. 1. [A] 2. [B] 3. [C] 4. [A]
Q:38. Match the explanations with the mandatory sings.
Ans:38. 1. [B] 2. [A] 3. [D] 4. [D] 5. [C]
Q:39. Match the different toraues with the labeled points in the graph.
Name of the torque
1) Breakdown torque
2) Starting torque
3) Full load torque
4) Rated torque
5) Torque at no load operation
Torque-speed characteristic
Ans:39. 1. [B] 2. [A] 3. [C] 4. [C] 5. [D]
Q:40. Match the type of instruments with the measurements.
Instruments
1) Pyrometer
2) Hydrometer
3) High rate discharge tester
4) Tong tester
5) Thermo-couple with a calibrated millivoltmeter
Measurements
A) To measure current without interrupting the circuit
B) Specific gravity of electrolyte of a car battery
C) To make, sure test of a battery after charging
D ) Temperature of a furnace
Ans:40. 1. [D] 2. [B] 3. [C] 4. [A] 5. [D]
Q:16. Chattering noise in DOL starter may be due to improper voltage,dirty pole faces and defective
spring in the NVC housing. You find all the above condition are ideal and still the problem persist.
What could be the other possible reason?
Ans:16. Broken pole shading ring.
Q:17. The small voltage fluctuation in the output of the rectifier is called ripple.
What is the ripple frequency of full wave rectifier?
Ans:17. 2f input.
Q:18. a) What is the purpose of transformers in regulated power supplies?
b) On what factor the output current regulated power supplies depend?
Ans:18. a)Stepping down AC voltage to the required AC voltage.
b) Load regulation.
Q:19. Universal motor control circuit is shown in the figure.
a) What is the function of the resistor R?
b) What are the consequences of a high and low value of resistance R with respect to speed
of the motor?
Ans:19. a) It varies the supply.
b) High value of resistance-slow speed
Low value of resistance- High speed
Q:20. Opening the switch of an inductive circuit sets an arc across the switch contacts due to large
voltage induced and stored energy magnetic field.
The arc is suppressed in such circuits by connecting........
A) a capacitor across the supply.
B) a capacitor across the switch contacts.
C) arcing horns across the switch contacts.
D) another small inductor across the switch contacts in reverse direction
Ans:20. B) a capacitor across the switch contacts.
Q:21. Every appliance should be tested for insulation resistance before commissioning. For a water
heater the insulation resistance should not be less than..........
A) 1 Meg ohm
B) 2 Meg ohm
C) 0.5 Meg ohm.
D) 0.25 Meg ohm
Ans:21. A) 1 Meg ohm.
Q:22. As a precautionary measure the heating element used in heaters, electric iron and water heaters
should not attain a temperature more than......
A) 335 degree
B) 635 degree.
C) 735 degree.
D) 1035 degree.
Ans:22. D) 1035 degree
Q:23. When a house wife accidently touched the metal part of the handle of a kettle. Which was
kept 'on'. She received an electric shock.
The reason is........
A) The fuse wire in the circuit is of higher capacity
B) The kettle is not earthed
C)There is no water in the kettle
D) The safety plug has become defective.
Ans:23. B) The kettle is not earthed
Q:24. What is the value of resistor in the circuit shown and its power rating you would select
for this function?
A) 2 W, 3.2 k ohm
B) 2 W, 6.4 K ohm
C) 4 W, 3.2 K ohm
D) 4 W, 6.4 K ohm
Ans:24. D) 4 W, 6.4 K ohm.
Q:25. Tong tester is used to measure the current in AC circuit without interrupting the circuit.
For measurement the split core is clamped on to the insulated current carrying conductor.
Looping of conductor passing through the split core is used some times.
What will be the reading for a selected range if the conductor is looped (double pass)?
A) Double the current which pass through the conductor.
B) 4 times (i.e., 22) the current which pass through the conductor.
C) Half the current which pass through the conductor.
D) Same as the conductor current.
Ans:25. A) Double the current which pass through the conductor.
Q:26. The direction of rotation of a permanent capacitor motor can be reversed by interchanging the ......
A) Centrifugal switch terminals
B) Auxiliary winding terminals
C) Capacitor terminals
D) Supply terminals
Ans:26. B) Auxiliary winding terminals.
Q:27. Which type of fault is tested in the above figure?
A) Testing the continuity of each winding.
B) Testing for open circuits.
C) Testing for grounds.
D) Testing the resistance value between each winding.
Ans:27. C) Testing for grounds.
Q:28. You have to change the defective induction motor of a machine. The available motor is of a
higher capacity than the existing one.
What is the effect of using a higher capacity motor?
A) The new motor will be overheated.
B) The new motor is better suitable for this work.
C) The efficiency and the power factor will become low.
D) The new motor has a longer useful working life and efficiency.
Ans:28. C) The efficiency and the power factor will become low.
Q:29. Brush tension in a DC generator play very important role in its performance.
Excessive brush tension may.........
A) Slow down the speed of the machine
B) Decrease the output voltage
C) Increase the output voltage
D) Overheat the commutator and wear out the surface.
Ans:29. D) Overheat the commutator and wear out the surface.
Q:30. What are the ON / OFF terminals of a transistor when it is operated as a switch?
A) Collector to base
B) Collector to emitter
C) Base to collector
D) Emitter to base.
Ans:30. B) Collector to emitter
Q:31. Which colour wire is recommended for earth connection as per ISI code?
A) Red
B) Green
C) Black
D) Blue
Ans:31. B) Green
Q:32. If single phasing occurs during running of a 3 phase motor, What is the effect on motor
performance?
A) Motor will run as 2 phase motor and performs normally.
B) Will continue to run on 2 phases but fails to take load.
C) Continue to run on 2 phases, draws excess current,winding likely to burn.
D) Run at reduced sspeed and can take only 2/3 of the load
Ans:32. C) Continue to run on 2 phases, draws excess current,winding likely to burn.
Q:33. The precision of measurement depends on the range of the instrument selected.
What is the general rule for selection of range of instrument?
Measured value should be.........
A) Above the mid-scale
B) Below the mid-scale
C) On the mid-scale
D) Exactly on full scale
Ans:33. A) Above the mid-scale.
Q:34. Rotor resistance starters are used with wound rotor induction motor,
When the motor is running the resistance in starter are........
A) Shorted
B) Open circuited
C) Connected in delta
D) Connected in star
Ans:34. A) Shorted
Q:35. How the PF meter is connected in the motor circuit?
A) Fixed coil in parallel with the supply and moving coil in series with single phase motor.
B) Fixed coil across the motor and moving coil across the supply.
C) Fixed coil in series with motor and moving coil across the supply.
D) Both Fixed coil and moving coil in series with the motor.
Ans:35. A) Fixed coil in parallel with the supply and moving coil in series with single phase motor.
Q:36. You have to change the defective motor of an electric locomotive.
Which type of motor would you choose?
A) DC differential compound motor.
B) DC shunt motor.
C) DC series motor.
D) Separately excited motor.
Ans:36. C) DC series motor.
Q:37. Match the materials with the parts of U.G cable
Materials
1) Copper
2) Lead (or) Lead Alloy
3) Steel wire
4) Aluminium
Parts of Underground cable
A) Core
B) Metallic sheath
C) Armouring
Ans:37. 1. [A] 2. [B] 3. [C] 4. [A]
Q:38. Match the explanations with the mandatory sings.
Explanations
1. Wear hearing protection.
2. Use adjustable guard.
3. Wear safety harness
4. Wear safety belt.
5. Wear foot protection
Mandatory sings
Ans:38. 1. [B] 2. [A] 3. [D] 4. [D] 5. [C]
Q:39. Match the different toraues with the labeled points in the graph.
Name of the torque
1) Breakdown torque
2) Starting torque
3) Full load torque
4) Rated torque
5) Torque at no load operation
Torque-speed characteristic
Ans:39. 1. [B] 2. [A] 3. [C] 4. [C] 5. [D]
Q:40. Match the type of instruments with the measurements.
Instruments
1) Pyrometer
2) Hydrometer
3) High rate discharge tester
4) Tong tester
5) Thermo-couple with a calibrated millivoltmeter
Measurements
A) To measure current without interrupting the circuit
B) Specific gravity of electrolyte of a car battery
C) To make, sure test of a battery after charging
D ) Temperature of a furnace
Ans:40. 1. [D] 2. [B] 3. [C] 4. [A] 5. [D]
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