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