Electrical Engineering Exercises: Generators, Motors, and Transformers | Exams Electrical and Electronics Engineering

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1. In three phase generator, the windings have voltages generated with an angle out of phase by what angle?

a. 360 degrees b. 180 degrees c. 120 degrees d. 90 degrees

2. In an alternator, the frequency is directly proportional to _____ and _____.

a. Torque and speed c. Poles and Speed

b. Torque and voltage d. Voltage and current

3. A balanced three-phase connection where the phase current is always approximately equal to 57.7% of the line

current.

a. Delta-connected 3 phase system c. Open-Delta connection

b. Star (wye) – connected 3 phase system d. Series-parallel connection

4. For a multiple generating unit to be operated in parallel, the equipment will show when the incoming unit is to be

synchronized with the running unit.

a. Circuit breaker b. Relay c. Synchronoscope d. Oscilloscope

5. This causes the difference between the no-load and full-load voltage of alternator.

a. Voltage regulation c. Voltage drop due to coil reactance

b. Voltage drop due to coil resistance d. Voltage drop due to coil impedance

6. It refers an external dc supply which causes the production of magnetic field in the field windings.

a. Battery b. Commutator c. Exciter d. Generator

7. A power plant station (PPS) wherein the electrical energy is derived from steam.

a.Diesel-Engine PPS c. Geo-thermal PPS

b. Hydro-Electric PPS d. Wind-Turbine PPS

8. In the operation of turbo-generator sets, which situation is applicable?

a. Alternator’s speed is higher than turbine’s speed

b. Alternator’s speed is lower than turbine’s speed

c. Alternator’s speed and turbine’s speed are just the same

d. Alternator’s speed varies as turbine’s speed

9. A type of motor that can be operated in either AC or DC source.

a. Squirrel-cage motor c. Synchronous motor

b. Wound-rotor motor d. Universal motor

10. What specific conditions in the performance characteristic of induction motor when it is designed at low

operating speed?

a. Torque is low c. Low current

b. Torque is high d. Small number of poles

11. This motor can be used and act as a generator where the rotor is applied with dc voltage also known as exciter

while the ac voltage is applied to the stator.

a. Split-phase motor c. Squirrel-cage motor

b. Synchronous motor d. Wound-rotor motor

12. This is the most common type of three-phase motor usually rated above fractional HP size, which is practically

used for ventilating units or water pumps.

a. Wound-rotor motor c. Squirrel-cage motor

b. Synchronous motor d. Capacitor-start motor

13. A type of electric motor that can be used in AC and DC source.

a. Capacitor-start motor c. Split-phase motor

b. Squirrel-cage motor d. Universal motor

14. In a three-phase machine with a given impedance or power triangle, the power factor (PF) can be represented by

what relationship?

a. PF = R / X b. PF = R / Z c. PF = P / S d. both (b) and (c)

15. A 240 volt shunt motor has an armature resistance of 0.38 ohm, what current will flow in the armature when the

back voltage is about 227.5 volts? Assume 2V brush drop.

a. 17.63 A b. 27.63A c. 37.63A d. 47.63A

16. In problem 15, what is the armature-circuit voltage drop?

a. 12.499V b. 10.499V c. 8.499V d. 6.499V

17. A 50-HP, 600V, compound dc motor operates at a speed of 495 RPM at full load. If the flux per pole is

9.1 x 10 6 Maxwell and the armature resistance of 0.015 ohm, how much is the counter EMF? If constant

K = 1.3 x 10 7.

a. 855.58V b. 558.85V c. 885.58V d. 585.85V

18. A 150 KW, 250V, compound dc generator is connected LONG SHUNT. If the shunt filed coil has a resistance of

20 ohms, what amperes will pass in the series filed current?

a. 612.5A b. 512.5A c. 412.5A d. 312.5A

19. A 9HP,460V,3 phase,60Hz, and a 4-pole squirrel cage induction motor operates at full load with an efficiency of

89%, 0.80 PF and 8.5% slip, the full-load speed will be _____

a. 1747RPM b. 1647RPM c. 1547RPM d. 1447RPM

20. In problem (19), how much full-load current is drawn by the motor from the line?

a. 11.83A b. 10.53A c. 9.47A d. 8.43A

21. If a motor is operating at 50 Hertz, what is the specific speed?

a. 1800RPM b. 2000RPM c. 2400RPM d. 3000RPM

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NAME: DATE:

SUBJECT/SECTION: INSTRUCTOR:

Direction : Write the letter of your answer on the space before the number. (Show your solution).

In three phase generator, the windings have voltages generated with an angle out of phase by what angle? a. 360 degrees b. 180 degrees c. 120 degrees d. 90 degrees
In an alternator, the frequency is directly proportional to _____ and _____. a. Torque and speed c. Poles and Speed b. Torque and voltage d. Voltage and current
A balanced three-phase connection where the phase current is always approximately equal to 57.7% of the line current. a. Delta-connected 3 phase system c. Open-Delta connection b. Star (wye) – connected 3 phase system d. Series-parallel connection
For a multiple generating unit to be operated in parallel, the equipment will show when the incoming unit is to be synchronized with the running unit. a. Circuit breaker b. Relay c. Synchronoscope d. Oscilloscope
This causes the difference between the no-load and full-load voltage of alternator. a. Voltage regulation c. Voltage drop due to coil reactance b. Voltage drop due to coil resistance d. Voltage drop due to coil impedance
It refers an external dc supply which causes the production of magnetic field in the field windings. a. Battery b. Commutator c. Exciter d. Generator
A power plant station (PPS) wherein the electrical energy is derived from steam. a.Diesel-Engine PPS c. Geo-thermal PPS b. Hydro-Electric PPS d. Wind-Turbine PPS
In the operation of turbo-generator sets, which situation is applicable? a. Alternator’s speed is higher than turbine’s speed b. Alternator’s speed is lower than turbine’s speed c. Alternator’s speed and turbine’s speed are just the same d. Alternator’s speed varies as turbine’s speed
A type of motor that can be operated in either AC or DC source. a. Squirrel-cage motor c. Synchronous motor b. Wound-rotor motor d. Universal motor
What specific conditions in the performance characteristic of induction motor when it is designed at low operating speed? a. Torque is low c. Low current b. Torque is high d. Small number of poles
This motor can be used and act as a generator where the rotor is applied with dc voltage also known as exciter while the ac voltage is applied to the stator. a. Split-phase motor c. Squirrel-cage motor b. Synchronous motor d. Wound-rotor motor
This is the most common type of three-phase motor usually rated above fractional HP size, which is practically used for ventilating units or water pumps. a. Wound-rotor motor c. Squirrel-cage motor b. Synchronous motor d. Capacitor-start motor
A type of electric motor that can be used in AC and DC source. a. Capacitor-start motor c. Split-phase motor b. Squirrel-cage motor d. Universal motor
In a three-phase machine with a given impedance or power triangle, the power factor (PF) can be represented by what relationship? a. PF = R / X b. PF = R / Z c. PF = P / S d. both (b) and (c)
A 240 volt shunt motor has an armature resistance of 0.38 ohm, what current will flow in the armature when the back voltage is about 227.5 volts? Assume 2V brush drop. a. 17.63 A b. 27.63A c. 37.63A d. 47.63A
In problem 15, what is the armature-circuit voltage drop? a. 12.499V b. 10.499V c. 8.499V d. 6.499V
A 50-HP, 600V, compound dc motor operates at a speed of 495 RPM at full load. If the flux per pole is 9.1 x 10 6 Maxwell and the armature resistance of 0.015 ohm, how much is the counter EMF? If constant K = 1.3 x 10 7. a. 855.58V b. 558.85V c. 885.58V d. 585.85V
A 150 KW, 250V, compound dc generator is connected LONG SHUNT. If the shunt filed coil has a resistance of 20 ohms, what amperes will pass in the series filed current? a. 612.5A b. 512.5A c. 412.5A d. 312.5A
A 9HP,460V,3 phase,60Hz, and a 4-pole squirrel cage induction motor operates at full load with an efficiency of 89%, 0.80 PF and 8.5% slip, the full-load speed will be _____ a. 1747RPM b. 1647RPM c. 1547RPM d. 1447RPM
In problem (19), how much full-load current is drawn by the motor from the line? a. 11.83A b. 10.53A c. 9.47A d. 8.43A
If a motor is operating at 50 Hertz, what is the specific speed? a. 1800RPM b. 2000RPM c. 2400RPM d. 3000RPM

A 3-phase generator is rated at 100KVA has an average PF of 80% at full-load efficiency of 91%, how much reactive power is delivered by generator to the load? a. 60KVAR b. 80KVAR c. 100KVAR d. 125KVAR
In problem (22), what is HP equivalent used by the engine coupled to drive this generator? a. 87.91HP b. 97.91HP c. 107.91HP d. 117.91HP 24 A 15HP, 3-Phase, 4 pole, 60Hertz, Squirrel Cage IM operates at full load with 0.80 PF and 12% slip, then the full-load torque is approximately_____ a. 39.73 lbs-ft b. 49.73 lbs-ft c. 59.73 lbs-ft d. 69.73 lbs-ft
Necessary condition to operate two transformers in parallel a. Operate at the same frequency. b. The voltage ratings must be in proportion to the load shared c. They must have equal KVA ratings d. Their ratio of transformation must be in proportion to the load shared
It is the fall in voltage from no-load condition to rated –load condition and is expressed either in per unit or percentage of the no load voltage at constant primary voltage. a. voltage drop c. voltage regulation b. impedance drop d. voltage sag
Which of the following characteristics is not appropriate for a transformer? a. At with load, it has a variable power factor b. Transform electrical energy from one into another circuits. c. It changes voltage from high to low d. Stationary device in which it is desirable to any frequency.
A termed voltage induced in the coil of transformer or alternator based on Faraday ’s Law of Electromagnetic induction. a. Primary Voltage b. Secondary Voltage c. Counter EMF d. Electromotive Force
In a power transmission system, step-up power transformer is usually used in order to; a. Reduce the voltage from high to low value. b. Increase the current from low to high value. c. Increase the magnitude of voltage at the secondary side d. Reduce the necessary apparent power by the load.
The anti-phase current in transformer is directly proportional to; a. No-load current c. Magnetizing current b. Primary current d. Load current
An induction motor (IM) that is constructed in a manner that the armature coils are housed and is practically in most fractional HP rating. a. Wound rotor IM c. Squirrel cage IM b. Synchronous IM d. Universal mototr
An autotransformer is rated 50 KVA, 13800 / 7200 volts supplying a load of 50KVA at 70.7% lagging PF. What is the transformed power when this transformer is operating at full-load condition? a. 14.88 KW b. 15.65 KW c. 16.91 KW d. 17.63KW
A 50 MVA power transformer has a reactance drop of 2.8% and resistance drop of 1.2% , what percent regulation of this transformer is obtained at 0.8 lagging PF? a. 2.65% b. 3.02% c. 4.06% d. 5.65%
1. Two distribution transformers are operate in parallel. Unit 1 - 10Kva, 4600:230 V, Ze-s = 0.16 ohm while Unit 2 – 7.5 Kva, 4485:230 V, Ze-s = 0.22 ohm, the circulating current at secondary is approximately___ a. 12.45A b. 15.35 A c. 16.87 A d. 17.30 A
2. A polarity test is performed upon a 1150/115 – volt transformer. If the applied input voltage is 116V, what would be the subtractive and additive voltage through the voltmeter reading? a. 127.60V & 104.4V c. 146.50V & 103.50V b. 137.50V & 114.5V d. 156.60V & 126.50V
Three 10:1 step-up transformer are connected delta primary and wye secondary for stepping up the 2300-volt three-phase source. What is the secondary line voltage? a. 400V b. 2300V c. 4000V d. 40000V
A single-phase induction motor is designed at 377 radian per sec., what is the specific speed? a. 900 RPM b. 1200 RPM c. 1800 RPM d. 3600 RPM
A 3-phase 40HP,460V,60Hz, Wound Rotor IM has an average efficiency of 83.5% at 0.75 power factor. What is the appropriate AT size of CB and size of wire for this motor? a. 50AT A,#8AWG b. 100AT,#1/0AWG c. 1 50AT,#6AWG d. 250AT, 250MCM
A 10HP, 3-Phase, and a 4-pole SCIM operates at full load with an efficiency of 89% and 80% PF. What would be the operating speed if the slip factor is 0.15? a. 1530 RPM b. 1760 RPM c. 1800 RPM d. 2016 RPM
For problem no.39, what is the rated starting torque of the SCIM if the starting torque is 250% of the rated torque? a. 85.81 lbs-ft b. 34.32 lbs-ft c. 29.17 lbs-ft d. 13.73 lbs-ft
1. A two-wattmeter is applied at the lines of 3-phase, 220V induction motor. If WMRA and WMRB reads 8.5 Kw and 5.5Kw, determine the operating power factor of this motor? a. 0.9770 b. 0.9375 c. 0.8770 d.0.
What is the average voltage generated in six turn full pitch coil of a 25-cycle alternator if the flux per pole is 7.2 x 10^5 Maxwells?

For generating units to be operated in parallel, the equipment will show when the incoming unit is to be synchronized with the running unit. a. Circuit Breaker b. Relay c. Synchronoscope d. Oscilloscope
This causes the difference between the no-load and full-load voltage of alternator. a. Voltage regulation c. Voltage drop due to coil reactance b. Voltage drop due to coil resistance d. Voltage drop due to coil impedance
It refers an external dc supply which causes the production of magnetic field in the field windings. a. Battery b. Commutator c. Exciter d. Generator
A power plant station (PPS) wherein the electrical energy is derived from steam. b.Diesel-Engine PPS c. Geo-thermal PPS b. Hydro-Electric PPS d. Wind-Turbine PPS
In the operation of turbo-generator sets, which situation is applicable? a. Alternator’s speed is higher than turbine’s speed b. Alternator’s speed is lower than turbine’s speed c. Alternator’s speed and turbine’s speed are just the same d. Alternator’s speed varies as turbine’s speed
A type of motor that can be operated in either AC or DC source. a. Squirrel-cage motor c. Synchronous motor b. Wound-rotor motor d. Universal motor
What specific conditions in the performance characteristic of induction motor when it is designed at low operating speed? a. Torque is low c. Low current b. Torque is high d. Small number of poles
This motor can be used and act as a generator where the rotor is applied with dc voltage also known as exciter while the ac voltage is applied to the stator. a. Split-phase motor c. Squirrel-cage motor b. Synchronous motor d. Wound-rotor motor
This is the most common type of three-phase motor usually rated above fractional HP size, which is practically used for ventilating units or water pumps. a. Wound-rotor motor c. Squirrel-cage motor b. Synchronous motor d. Capacitor-start motor
A type of electric motor that can be used in AC and DC source. a. Capacitor-start motor c. Split-phase motor b. Squirrel-cage motor d. Universal motor
In a three-phase machine with a given impedance or power triangle, the power factor (PF) can be represented by what relationship? a. PF = R / X b. PF = R / Z c. PF = P / S d. both (b) and (c)
A 240 volt shunt motor has an armature resistance of 0.38 ohm, what current will flow in the armature when the back voltage is about 227.5 volts? Assume 2V brush drop. a. 17.63 A b. 27.63A c. 37.63A d. 47.63A
In problem 15, what is the armature-circuit voltage drop? a. 12.499V b. 10.499V c. 8.499V d. 6.499V
A 50-HP, 600V, compound dc motor operates at a speed of 495 RPM at full load. If the flux per pole is 9.1 x 10 6 Maxwell and the armature resistance of 0.015 ohm, how much is the counter EMF? If constant K = 1.3 x 10 7. a. 855.58V b. 558.85V c. 885.58V d. 585.85V
A 150 KW, 250V, compound dc generator is connected LONG SHUNT. If the shunt filed coil has a resistance of 20 ohms, what amperes will pass in the series filed current? a. 612.5A b. 512.5A c. 412.5A d. 312.5A
A 9HP,460V,3 phase,60Hz, and a 4-pole squirrel cage induction motor operates at full load with an efficiency of 89%, 0.80 PF and 8.5% slip, the full-load speed will be _____ a. 1747RPM b. 1647RPM c. 1547RPM d. 1447RPM
In problem (19), how much full-load current is drawn by the motor from the line? a. 11.83A b. 10.53A c. 9.47A d. 8.43A
If a motor is operating at 50 Hertz, what is the specific speed? a. 1800RPM b. 2000RPM c. 2400RPM d. 3000RPM
A 3-phase generator is rated at 100KVA has an average PF of 80% at full-load efficiency of 91%, how much reactive power is delivered by generator to the load? a. 60KVAR b. 80KVAR c. 100KVAR d. 125KVAR
In problem (22), what is HP equivalent used by the engine coupled to drive this generator? a. 87.91HP b. 97.91HP c. 107.91HP d. 117.91HP 24 A 15HP, 3-Phase, 4 pole, 60Hertz, Squirrel Cage IM operates at full load with 0.80 PF and 12% slip, then the full-load torque is approximately_____ a. 39.73 lbs-ft b. 49.73 lbs-ft c. 59.73 lbs-ft d. 69.73 lbs-ft
Necessary condition to operate two transformers in parallel a. Operate at the same frequency. b. The voltage ratings must be in proportion to the load shared d. They must have equal KVA ratings d. Their ratio of transformation must be in proportion to the load shared
It is the fall in voltage from no-load condition to rated –load condition and is expressed either in per unit or percentage of the no load voltage at constant primary voltage.

a. voltage drop c. voltage regulation b. impedance drop d. voltage sag

Which of the following characteristics is not appropriate for a transformer? a. At with load, it has a variable power factor b. Transform electrical energy from one into another circuits. c. It changes voltage from high to low d. Stationary device in which it is desirable to any frequency.
A termed voltage induced in the coil of transformer or alternator based on Faraday ’s Law of Electromagnetic induction. a. Primary Voltage b. Secondary Voltage c. Counter EMF d. Electromotive Force
In a power transmission system, step-up power transformer is usually used in order to; a. Reduce the voltage from high to low value. b. Increase the current from low to high value. c. Increase the magnitude of voltage at the secondary side d. Reduce the necessary apparent power by the load.
The anti-phase current in transformer is directly proportional to; c. No-load current c. Magnetizing current d. Primary current d. Load current
An induction motor (IM) that is constructed in a manner that the armature coils are housed and is practically in most fractional HP rating. c. Wound Rotor IM c. Squirrel Cage IM d. Synchronous IM d. Universal mototr
An autotransformer is rated 50 KVA, 13800 / 7200 volts supplying a load of 50KVA at 70.7% lagging PF. What is the transformed power when this transformer is operating at full-load condition? a. 14.88 KW b. 15.65 KW c. 16.91 KW d. 17.63KW
A 50 MVA power transformer has a reactance drop of 2.8% and resistance drop of 1.2% , what percent regulation of this transformer is obtained at 0.8 lagging PF? a. 2.65% b. 3.02% c. 4.06% d. 5.65%
1. Two distribution transformers are operate in parallel. Unit 1 - 10Kva, 4600:230 V, Ze-s = 0.16 ohm while Unit 2 – 7.5 Kva, 4485:230 V, Ze-s = 0.22 ohm, the circulating current at secondary is approximately___ a. 12.45A b. 15.35 A c. 16.87 A d. 17.30 A
2. A polarity test is performed upon a 1150/115 – volt transformer. If the applied input voltage is 116V, what would be the subtractive and additive voltage through the voltmeter reading? a. 127.60V and 104.4V c. 146.50V and 103.50V b. 137.50V and 114.5V d. 156.60V and 126.50V
Three 10:1 step-up transformer are connected delta primary and wye secondary for stepping up the 2300-volt three-phase source. What is the secondary line voltage? a. 400V b. 2,300V c. 4,000V d. 40,000V
A single-phase induction motor is designed at 377 radian per sec., what is the specific speed? a. 900 RPM b. 1200 RPM c. 1800 RPM d. 3600 RPM
A 3-phase 40HP,460V,60Hz, Wound Rotor IM has an average efficiency of 83.5% at 0.75 power factor. What is the appropriate AT size of CB and size of wire for this motor? a. 50AT A b. 100AT c. 150AT,#6AWG d. 250AT,
A 10HP, 3-Phase, and a 4-pole SCIM operates at full load with an efficiency of 89% and 80% PF. What would be the operating speed if the slip factor is 0.15? a. 1530 RPM b. 1760 RPM c. 1800 RPM d. 2016 RPM
For problem no.39, what is the rated starting torque of the SCIM if the starting torque is 250% of the rated torque? a. 85.81 lbs-ft b. 34.32 lbs-ft c. 29.17 lbs-ft d. 13.73 lbs-ft
A two-wattmeter is applied at the lines of 3-phase, 220V induction motor. If WMRA and WMRB reads 8.5 Kw and 5.5Kw, determine the operating power factor of this motor? a. 0.9770 b. 0.9375 c. 0.8770 d.0.
What is the average voltage generated in six turn full pitch coil of a 25-cycle alternator if the flux per pole is 7.2 x 10^5 Maxwells? a. 3.892 V b. 4.225 V c. 4.320 V d.6.109 V
For problem 42, what is the effective voltage? a. 4.320 V b. 4.690 V c. 4.795 V d.6.781 V
A 90-slot stator has a 3-phase 6 – pole whole-coiled winding, each coil of which spans from slot 1 to slot 14, then the pitch factor will be_____ a. 0.978 b. 0.957 c. 0.789 d. 0.
The percent regulation of a 3-phase alternator is 16.304%. If the rated voltage is 460 Volts, what is the zero-load voltage? a. 585 V b. 555 V c. 545 V d. 535 V
In the analysis of short transmission lines which of the following is neglected? a. I 2 R loss b. shunt admittance c. series impedance d. None of these
Line loss of a transmission line for a give power is inversely proportional to; a. line resistance and current c. line impedance and current b. frequency d. supply voltage and power factor

Electrical Engineering Exercises: Generators, Motors, and Transformers, Exams of Electrical and Electronics Engineering

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Partial preview of the text

Download Electrical Engineering Exercises: Generators, Motors, and Transformers and more Exams Electrical and Electronics Engineering in PDF only on Docsity!

NAME: DATE:

SUBJECT/SECTION: INSTRUCTOR: