12100083
Descrição
Quiz por Kaitlyn Hickey, atualizado more than 1 year ago
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Criado por Kaitlyn Hickey
quase 7 anos atrás
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Questão 1
Questão
What is the maximum number of trip coils required for a three phase motor?
Responda
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2
-
3
-
5
-
Not required
Questão 2
Questão
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?
Responda
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Resistance-start induction-run
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Squirrel-cage induction
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Synchronous
-
Wound-rotor induction
Questão 3
Questão
What is the maximum time-delay fuse that can be used with a three-phase motor of the full load current?
Responda
-
125%
-
175%
-
225%
-
300%
Questão 4
Questão
How can locked rotor current be described?
Responda
-
It is the current that wound rotor motor reaches at synchronous speed
-
It’s the full load current of a squirrel cage motor
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It’s the stall current of a three-phase motor
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It’s the starting current of a squirrel cage motor
Questão 5
Questão
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?
Responda
-
125%
-
225%
-
300%
-
400%
Questão 6
Questão
What is the basic principle of operation for all three-phase motors?
Responda
-
A rotating magnetic field
-
DC field operation
-
Brushless field excitation
-
Maintenance
Questão 7
Questão
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?
Responda
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50-100 percent
-
100-200 percent
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200-300 percent
-
300-400 percent
Questão 8
Questão
What is the phase voltage of a three-phase 600 volt squirrel cage connected delta?
Responda
-
208V
-
347V
-
600V
-
750 V
Questão 9
Questão
What does the service factor reveal about the motor?
Responda
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The length of time the motor may be operated before resting
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The expected life of a motor
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How often the motor should be serviced
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How much of the motor can be continuously loaded without damaging it
Questão 10
Questão
What is the conduction called if one phase of a three-phase motor opens?
Responda
-
Double phasing
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Single phasing
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Triple phasing
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Free running
Questão 11
Questão
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?
Responda
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75C
-
90C
-
110C
-
125C
Questão 12
Questão
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?
Responda
-
Lugs
-
Polarity
-
Continuity
-
Rotation
Questão 13
Questão
What is the temperature rating of the conductors supplying a motor with a class H insulation rating?
Responda
-
90C
-
100C
-
110C
-
120C
Questão 14
Questão
What is the maximum feeder conductor ampacity required to supply a bank of three phase motor are: 96 A, 27A, and 156A
Responda
-
279A
-
318A
-
337A
-
303A
Questão 15
Questão
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
Responda
-
#1/0 AWG
-
#1 AWG
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#400mcm
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#2/0 AWG
Questão 16
Questão
What is the speed at 60 Hz of a 12 pole synchronous motor?
Responda
-
120 rpm
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300rpm
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600 rpm
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1200rpm
Questão 17
Questão
In a wound rotor motor, the torque characteristic can be altered by?
Responda
-
Adding or removing external resistance
-
Adding and removing external inductance
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Adding or removing external capacitance
-
Torque may not be altered
Questão 18
Questão
Three-phase motor windings are installed ____ electrical degrees apart from each other
Responda
-
90
-
120
-
180
-
270
Questão 19
Questão
What is the term used to describe the amount of torque required to pull the rotor into synchronous speed?
Responda
-
Cut-out torque
-
Cut-in torque
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Pull-out torque
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Pull-in torque
Questão 20
Questão
What is the term used to describe the angle between the centre of the stator pole and the centre is the rotor pole?
Responda
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Torque angle
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Angle of incidence
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Phasing angle
-
Synchronous angle
Questão 21
Questão
What is the advantage of a synchronous motor?
Responda
-
Constant speed from no load to full load
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Lower voltage starting
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Can run on either AC and DC
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Speed can be controlled
Questão 22
Questão
What size time-delay fuse is required for a three phase, 25hp, 600v, scim
Responda
-
20 A
-
30A
-
15A
-
40A
Questão 23
Questão
What meter is used to check phasing in a 3-phase motor when it is de-energized and out of service?
Responda
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Clamp-on meter
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Multimeter
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Phase rotation meter
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Phase sequence meter
Questão 24
Questão
What powers the field generation in a typical synchronous motor?
Responda
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External resistor
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External DC source
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External AC source
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External capacitors
Questão 25
Questão
The basic principle of all 3 phase motors for synchronous motor is?
Responda
-
Reluctance
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Capacitance
-
Induction
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Rotation
Questão 26
Questão
By checking leads T7, T8, T9 of a nine lead motor, an electrician can determine
Responda
-
The voltage of the motor
-
The FLA of the motor
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The winding connection (wye or delta)
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The service factor of the motor
Questão 27
Questão
What are synchronous motor mainly used for
Responda
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Fan
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Pumps
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Compressors
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All of the above
Questão 28
Questão
The insulation class rating of a totally enclosed non-ventilated motor operating at 90 degrees is
Responda
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Type A
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Type F
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Type B
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Type H
Questão 29
Questão
In dual voltage 3 phase motors, the leads are connected in ____ for low voltage and in ____ for high voltage
Responda
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Parallel-series
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Series-parallel
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Delta-wye
-
Wye-delta
Questão 30
Questão
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.
Responda
-
115%
-
150%
-
200%
-
300%
Questão 31
Questão
Which markings are used to designate the rotor terminals of a wound rotor motor?
Responda
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L1 L2 L3
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F1 F2 F3
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M1 M2 M3
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T1 T2 T3
Questão 32
Questão
In order to not trip, what is the maximum percent rating for an instaneous trip circuit breaker of an AC motor?
Responda
-
700%
-
900%
-
1300%
-
1500%
Questão 33
Questão
What is the speed of rotation of the magnetic field called in a three-phased motor?
Responda
-
Magnetic
-
Slip
-
Synchronous
-
Rotor
Questão 34
Questão
What is the proper rating of a time-delay fuse for a 230v, 22.38 KW, auto-transformer start continuous duty motor
Responda
-
100Amp
-
125Amp
-
150Amp
-
225Amp
Questão 35
Questão
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?
Responda
-
1700 RPM
-
1900 RPM
-
2000 RPM
-
2100 RPM
Questão 36
Questão
What is the purpose of the centrifugal switch in split phase motor?
Responda
-
It removes the start winding from the motor in split phase motors
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It adds the start winding from the motor circuit
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It removes the run winding from the motor circuit
-
It adds the run winding from the motor circuit
Questão 37
Questão
What is the speed at which the centrifugal switch of a split phase motor will operate?
Responda
-
60%
-
65%
-
70%
-
75%
Questão 38
Questão
How is the rotor of a 15 hp synchronous motor operating on line voltage excited?
Responda
-
AC voltage
-
Induced magnetic field
-
AC line voltage
-
DC current
Questão 39
Questão
Which starting method provides the highest torque per ampere?
Responda
-
Auto-transformer
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Across the line
-
Primary resistor
-
Wye-delta
Questão 40
Questão
What part of the wound rotor motor differs from that of a squirrel cage induction motor?
Responda
-
Stator
-
Rotor
-
End bells
-
Bearings
Questão 41
Questão
What size time delay fuse can be used on a 3 phase, 230V, auto transformer starting motor consuming 22.38 KW of power
Responda
-
70 amps
-
80amps
-
90 amps
-
100amps
Questão 42
Questão
What does increasing the frequency of the supply voltage to an induction motor cause?
Responda
-
Increased speed
-
Decreases speed
-
Increased torque
-
Decreased torque
Questão 43
Questão
A nine-lead dual voltage three-phase SCIM is connected in the lower voltage delta arrangement. Which terminals are connected to each other?
Responda
-
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
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L1-T1,L2-T2,L3-T3,T7-T4,T8-T5,T9-T6
Questão 44
Questão
What is the ampacity of conductors feeding a 3 phase, 230V, SCIM, continuous duty motor rated at 20hp, 10hp, 1Hp, and 5Hp?
Responda
-
77.1A
-
88.3A
-
114.9A
-
116.6A
Questão 45
Questão
What meter is used to check the input phasing before installing a three-phase motor?
Responda
-
Phase rotation meter
-
Wattmeter
-
Motor rotation meter
-
Syncroscope
Questão 46
Questão
What effect does increasing the frequency of the supply have on the speed of the rotating magnetic field?
Responda
-
Increases
-
Decreases
-
No change
-
Changes direction
Questão 47
Questão
How does the starting current of a split phase motor compare to its full load current?
Responda
-
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
Questão 48
Questão
What information is required to size the overload protection of a 15Hp l, 600V, three-phase motor?
Responda
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HP & FLA
-
SF AND FLA
-
V and FLA
-
Wire size and SF
Questão 49
Questão
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?
Responda
-
75.6%
-
90.8%
-
110%
-
157%
Questão 50
Questão
Which variables are identified by the motor service factor when considering the maximum continuous permissible load?
Responda
-
Voltage and amps
-
Voltage and frequency
-
Amps and frequency
-
RPM and voltage
Questão 51
Questão
A synchronous motor has a lagging power factor. How is the corrected?
Responda
-
Over excite the field
-
Add a capacitor
-
Increase the load reduce the load
-
Reduce the load
Questão 52
Questão
Which 3 phase motor provides maximum starting torque?
Responda
-
Capacitor run
-
Capacitor start
-
Induction run
-
Resistance run
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