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ER-2031 block review

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Quiz on ER-2031, created by Kaitlyn Hickey on 03/02/2018.
Kaitlyn Hickey
Quiz by Kaitlyn Hickey, updated more than 1 year ago
Kaitlyn Hickey
Created by Kaitlyn Hickey almost 7 years ago
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Resource summary

Question 1

Question
What is the maximum number of trip coils required for a three phase motor?
Answer
  • 2
  • 3
  • 5
  • Not required

Question 2

Question
What type of three phase motor has the ability to correct its own power factor and the power factor of other devices connected to the same line?
Answer
  • Resistance-start induction-run
  • Squirrel-cage induction
  • Synchronous
  • Wound-rotor induction

Question 3

Question
What is the maximum time-delay fuse that can be used with a three-phase motor of the full load current?
Answer
  • 125%
  • 175%
  • 225%
  • 300%

Question 4

Question
How can locked rotor current be described?
Answer
  • It is the current that wound rotor motor reaches at synchronous speed
  • It’s the full load current of a squirrel cage motor
  • It’s the stall current of a three-phase motor
  • It’s the starting current of a squirrel cage motor

Question 5

Question
The over current device will not permit a motor to start. What is the maximum time-delay fuse that can be used with a three-phase motor of the full load current?
Answer
  • 125%
  • 225%
  • 300%
  • 400%

Question 6

Question
What is the basic principle of operation for all three-phase motors?
Answer
  • A rotating magnetic field
  • DC field operation
  • Brushless field excitation
  • Maintenance

Question 7

Question
A wound rotor motor has a strong starting torque and maintains a smooth acceleration from start to full speed. What percent of full load torque is usually produced?
Answer
  • 50-100 percent
  • 100-200 percent
  • 200-300 percent
  • 300-400 percent

Question 8

Question
What is the phase voltage of a three-phase 600 volt squirrel cage connected delta?
Answer
  • 208V
  • 347V
  • 600V
  • 750 V

Question 9

Question
What does the service factor reveal about the motor?
Answer
  • The length of time the motor may be operated before resting
  • The expected life of a motor
  • How often the motor should be serviced
  • How much of the motor can be continuously loaded without damaging it

Question 10

Question
What is the conduction called if one phase of a three-phase motor opens?
Answer
  • Double phasing
  • Single phasing
  • Triple phasing
  • Free running

Question 11

Question
When installing an electrical motor that is totally enclosed, non-vented, with class F insulation rating, the conductors supplying it needs to be rated for what temperature?
Answer
  • 75C
  • 90C
  • 110C
  • 125C

Question 12

Question
A nine lead motor may be connected in wye or delta internally. If this connection is been tested by checking T7, T8, T9 what is it been tested for?
Answer
  • Lugs
  • Polarity
  • Continuity
  • Rotation

Question 13

Question
What is the temperature rating of the conductors supplying a motor with a class H insulation rating?
Answer
  • 90C
  • 100C
  • 110C
  • 120C

Question 14

Question
What is the maximum feeder conductor ampacity required to supply a bank of three phase motor are: 96 A, 27A, and 156A
Answer
  • 279A
  • 318A
  • 337A
  • 303A

Question 15

Question
What size of R90 copper conductor is used in a feeder conduit to supply three motors having a full load current of 100amps, 20 amps, and 10 amps? 75 degree rated
Answer
  • #1/0 AWG
  • #1 AWG
  • #400mcm
  • #2/0 AWG

Question 16

Question
What is the speed at 60 Hz of a 12 pole synchronous motor?
Answer
  • 120 rpm
  • 300rpm
  • 600 rpm
  • 1200rpm

Question 17

Question
In a wound rotor motor, the torque characteristic can be altered by?
Answer
  • Adding or removing external resistance
  • Adding and removing external inductance
  • Adding or removing external capacitance
  • Torque may not be altered

Question 18

Question
Three-phase motor windings are installed ____ electrical degrees apart from each other
Answer
  • 90
  • 120
  • 180
  • 270

Question 19

Question
What is the term used to describe the amount of torque required to pull the rotor into synchronous speed?
Answer
  • Cut-out torque
  • Cut-in torque
  • Pull-out torque
  • Pull-in torque

Question 20

Question
What is the term used to describe the angle between the centre of the stator pole and the centre is the rotor pole?
Answer
  • Torque angle
  • Angle of incidence
  • Phasing angle
  • Synchronous angle

Question 21

Question
What is the advantage of a synchronous motor?
Answer
  • Constant speed from no load to full load
  • Lower voltage starting
  • Can run on either AC and DC
  • Speed can be controlled

Question 22

Question
What size time-delay fuse is required for a three phase, 25hp, 600v, scim
Answer
  • 20 A
  • 30A
  • 15A
  • 40A

Question 23

Question
What meter is used to check phasing in a 3-phase motor when it is de-energized and out of service?
Answer
  • Clamp-on meter
  • Multimeter
  • Phase rotation meter
  • Phase sequence meter

Question 24

Question
What powers the field generation in a typical synchronous motor?
Answer
  • External resistor
  • External DC source
  • External AC source
  • External capacitors

Question 25

Question
The basic principle of all 3 phase motors for synchronous motor is?
Answer
  • Reluctance
  • Capacitance
  • Induction
  • Rotation

Question 26

Question
By checking leads T7, T8, T9 of a nine lead motor, an electrician can determine
Answer
  • The voltage of the motor
  • The FLA of the motor
  • The winding connection (wye or delta)
  • The service factor of the motor

Question 27

Question
What are synchronous motor mainly used for
Answer
  • Fan
  • Pumps
  • Compressors
  • All of the above

Question 28

Question
The insulation class rating of a totally enclosed non-ventilated motor operating at 90 degrees is
Answer
  • Type A
  • Type F
  • Type B
  • Type H

Question 29

Question
In dual voltage 3 phase motors, the leads are connected in ____ for low voltage and in ____ for high voltage
Answer
  • Parallel-series
  • Series-parallel
  • Delta-wye
  • Wye-delta

Question 30

Question
To find the size of fuse holders that accommodates fuses supplying a group of motors, you must take ____ off the largest motor current and add to this valve of the full load currents of all other motors in a group that may be in operation at the same time.
Answer
  • 115%
  • 150%
  • 200%
  • 300%

Question 31

Question
Which markings are used to designate the rotor terminals of a wound rotor motor?
Answer
  • L1 L2 L3
  • F1 F2 F3
  • M1 M2 M3
  • T1 T2 T3

Question 32

Question
In order to not trip, what is the maximum percent rating for an instaneous trip circuit breaker of an AC motor?
Answer
  • 700%
  • 900%
  • 1300%
  • 1500%

Question 33

Question
What is the speed of rotation of the magnetic field called in a three-phased motor?
Answer
  • Magnetic
  • Slip
  • Synchronous
  • Rotor

Question 34

Question
What is the proper rating of a time-delay fuse for a 230v, 22.38 KW, auto-transformer start continuous duty motor
Answer
  • 100Amp
  • 125Amp
  • 150Amp
  • 225Amp

Question 35

Question
A three-phase motor has a synchronous speed of 1800RPM, operates at a frequency of 60Hz and has a slip speed of 100RPM. What is the rotor speed of the motor?
Answer
  • 1700 RPM
  • 1900 RPM
  • 2000 RPM
  • 2100 RPM

Question 36

Question
What is the purpose of the centrifugal switch in split phase motor?
Answer
  • It removes the start winding from the motor in split phase motors
  • It adds the start winding from the motor circuit
  • It removes the run winding from the motor circuit
  • It adds the run winding from the motor circuit

Question 37

Question
What is the speed at which the centrifugal switch of a split phase motor will operate?
Answer
  • 60%
  • 65%
  • 70%
  • 75%

Question 38

Question
How is the rotor of a 15 hp synchronous motor operating on line voltage excited?
Answer
  • AC voltage
  • Induced magnetic field
  • AC line voltage
  • DC current

Question 39

Question
Which starting method provides the highest torque per ampere?
Answer
  • Auto-transformer
  • Across the line
  • Primary resistor
  • Wye-delta

Question 40

Question
What part of the wound rotor motor differs from that of a squirrel cage induction motor?
Answer
  • Stator
  • Rotor
  • End bells
  • Bearings

Question 41

Question
What size time delay fuse can be used on a 3 phase, 230V, auto transformer starting motor consuming 22.38 KW of power
Answer
  • 70 amps
  • 80amps
  • 90 amps
  • 100amps

Question 42

Question
What does increasing the frequency of the supply voltage to an induction motor cause?
Answer
  • Increased speed
  • Decreases speed
  • Increased torque
  • Decreased torque

Question 43

Question
A nine-lead dual voltage three-phase SCIM is connected in the lower voltage delta arrangement. Which terminals are connected to each other?
Answer
  • L1-T1, T7-T4, L2-T2, T8-T5, L3-T3, T9-T6
  • L1-T1-T7-T6, L2-T2-T8-T4, L3-T3-T9-T5
  • L1-T1-T8, L2-T2-T7, L3-T3-T9, T4-T5-T6
  • L1-T1,L2-T2,L3-T3,T7-T4,T8-T5,T9-T6

Question 44

Question
What is the ampacity of conductors feeding a 3 phase, 230V, SCIM, continuous duty motor rated at 20hp, 10hp, 1Hp, and 5Hp?
Answer
  • 77.1A
  • 88.3A
  • 114.9A
  • 116.6A

Question 45

Question
What meter is used to check the input phasing before installing a three-phase motor?
Answer
  • Phase rotation meter
  • Wattmeter
  • Motor rotation meter
  • Syncroscope

Question 46

Question
What effect does increasing the frequency of the supply have on the speed of the rotating magnetic field?
Answer
  • Increases
  • Decreases
  • No change
  • Changes direction

Question 47

Question
How does the starting current of a split phase motor compare to its full load current?
Answer
  • It’s much higher than the FLA
  • It’s much lower than the FLA
  • It’s equal to the FLA
  • It’s equal to the stall current

Question 48

Question
What information is required to size the overload protection of a 15Hp l, 600V, three-phase motor?
Answer
  • HP & FLA
  • SF AND FLA
  • V and FLA
  • Wire size and SF

Question 49

Question
A 5 Hp, 3 phase motor has a voltage of 208v and draw a 12A. It has a power factor of 95%. What is the efficiency?
Answer
  • 75.6%
  • 90.8%
  • 110%
  • 157%

Question 50

Question
Which variables are identified by the motor service factor when considering the maximum continuous permissible load?
Answer
  • Voltage and amps
  • Voltage and frequency
  • Amps and frequency
  • RPM and voltage

Question 51

Question
A synchronous motor has a lagging power factor. How is the corrected?
Answer
  • Over excite the field
  • Add a capacitor
  • Increase the load reduce the load
  • Reduce the load

Question 52

Question
Which 3 phase motor provides maximum starting torque?
Answer
  • Capacitor run
  • Capacitor start
  • Induction run
  • Resistance run
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