12100083
Descripción
Test por Kaitlyn Hickey, actualizado hace más de 1 año
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Creado por Kaitlyn Hickey
hace alrededor de 7 años
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Pregunta 1
Pregunta
What is the maximum number of trip coils required for a three phase motor?
Respuesta
-
2
-
3
-
5
-
Not required
Pregunta 2
Pregunta
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?
Respuesta
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Resistance-start induction-run
-
Squirrel-cage induction
-
Synchronous
-
Wound-rotor induction
Pregunta 3
Pregunta
What is the maximum time-delay fuse that can be used with a three-phase motor of the full load current?
Respuesta
-
125%
-
175%
-
225%
-
300%
Pregunta 4
Pregunta
How can locked rotor current be described?
Respuesta
-
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
Pregunta 5
Pregunta
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?
Respuesta
-
125%
-
225%
-
300%
-
400%
Pregunta 6
Pregunta
What is the basic principle of operation for all three-phase motors?
Respuesta
-
A rotating magnetic field
-
DC field operation
-
Brushless field excitation
-
Maintenance
Pregunta 7
Pregunta
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?
Respuesta
-
50-100 percent
-
100-200 percent
-
200-300 percent
-
300-400 percent
Pregunta 8
Pregunta
What is the phase voltage of a three-phase 600 volt squirrel cage connected delta?
Respuesta
-
208V
-
347V
-
600V
-
750 V
Pregunta 9
Pregunta
What does the service factor reveal about the motor?
Respuesta
-
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
Pregunta 10
Pregunta
What is the conduction called if one phase of a three-phase motor opens?
Respuesta
-
Double phasing
-
Single phasing
-
Triple phasing
-
Free running
Pregunta 11
Pregunta
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?
Respuesta
-
75C
-
90C
-
110C
-
125C
Pregunta 12
Pregunta
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?
Respuesta
-
Lugs
-
Polarity
-
Continuity
-
Rotation
Pregunta 13
Pregunta
What is the temperature rating of the conductors supplying a motor with a class H insulation rating?
Respuesta
-
90C
-
100C
-
110C
-
120C
Pregunta 14
Pregunta
What is the maximum feeder conductor ampacity required to supply a bank of three phase motor are: 96 A, 27A, and 156A
Respuesta
-
279A
-
318A
-
337A
-
303A
Pregunta 15
Pregunta
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
Respuesta
-
#1/0 AWG
-
#1 AWG
-
#400mcm
-
#2/0 AWG
Pregunta 16
Pregunta
What is the speed at 60 Hz of a 12 pole synchronous motor?
Respuesta
-
120 rpm
-
300rpm
-
600 rpm
-
1200rpm
Pregunta 17
Pregunta
In a wound rotor motor, the torque characteristic can be altered by?
Respuesta
-
Adding or removing external resistance
-
Adding and removing external inductance
-
Adding or removing external capacitance
-
Torque may not be altered
Pregunta 18
Pregunta
Three-phase motor windings are installed ____ electrical degrees apart from each other
Respuesta
-
90
-
120
-
180
-
270
Pregunta 19
Pregunta
What is the term used to describe the amount of torque required to pull the rotor into synchronous speed?
Respuesta
-
Cut-out torque
-
Cut-in torque
-
Pull-out torque
-
Pull-in torque
Pregunta 20
Pregunta
What is the term used to describe the angle between the centre of the stator pole and the centre is the rotor pole?
Respuesta
-
Torque angle
-
Angle of incidence
-
Phasing angle
-
Synchronous angle
Pregunta 21
Pregunta
What is the advantage of a synchronous motor?
Respuesta
-
Constant speed from no load to full load
-
Lower voltage starting
-
Can run on either AC and DC
-
Speed can be controlled
Pregunta 22
Pregunta
What size time-delay fuse is required for a three phase, 25hp, 600v, scim
Respuesta
-
20 A
-
30A
-
15A
-
40A
Pregunta 23
Pregunta
What meter is used to check phasing in a 3-phase motor when it is de-energized and out of service?
Respuesta
-
Clamp-on meter
-
Multimeter
-
Phase rotation meter
-
Phase sequence meter
Pregunta 24
Pregunta
What powers the field generation in a typical synchronous motor?
Respuesta
-
External resistor
-
External DC source
-
External AC source
-
External capacitors
Pregunta 25
Pregunta
The basic principle of all 3 phase motors for synchronous motor is?
Respuesta
-
Reluctance
-
Capacitance
-
Induction
-
Rotation
Pregunta 26
Pregunta
By checking leads T7, T8, T9 of a nine lead motor, an electrician can determine
Respuesta
-
The voltage of the motor
-
The FLA of the motor
-
The winding connection (wye or delta)
-
The service factor of the motor
Pregunta 27
Pregunta
What are synchronous motor mainly used for
Respuesta
-
Fan
-
Pumps
-
Compressors
-
All of the above
Pregunta 28
Pregunta
The insulation class rating of a totally enclosed non-ventilated motor operating at 90 degrees is
Respuesta
-
Type A
-
Type F
-
Type B
-
Type H
Pregunta 29
Pregunta
In dual voltage 3 phase motors, the leads are connected in ____ for low voltage and in ____ for high voltage
Respuesta
-
Parallel-series
-
Series-parallel
-
Delta-wye
-
Wye-delta
Pregunta 30
Pregunta
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.
Respuesta
-
115%
-
150%
-
200%
-
300%
Pregunta 31
Pregunta
Which markings are used to designate the rotor terminals of a wound rotor motor?
Respuesta
-
L1 L2 L3
-
F1 F2 F3
-
M1 M2 M3
-
T1 T2 T3
Pregunta 32
Pregunta
In order to not trip, what is the maximum percent rating for an instaneous trip circuit breaker of an AC motor?
Respuesta
-
700%
-
900%
-
1300%
-
1500%
Pregunta 33
Pregunta
What is the speed of rotation of the magnetic field called in a three-phased motor?
Respuesta
-
Magnetic
-
Slip
-
Synchronous
-
Rotor
Pregunta 34
Pregunta
What is the proper rating of a time-delay fuse for a 230v, 22.38 KW, auto-transformer start continuous duty motor
Respuesta
-
100Amp
-
125Amp
-
150Amp
-
225Amp
Pregunta 35
Pregunta
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?
Respuesta
-
1700 RPM
-
1900 RPM
-
2000 RPM
-
2100 RPM
Pregunta 36
Pregunta
What is the purpose of the centrifugal switch in split phase motor?
Respuesta
-
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
Pregunta 37
Pregunta
What is the speed at which the centrifugal switch of a split phase motor will operate?
Respuesta
-
60%
-
65%
-
70%
-
75%
Pregunta 38
Pregunta
How is the rotor of a 15 hp synchronous motor operating on line voltage excited?
Respuesta
-
AC voltage
-
Induced magnetic field
-
AC line voltage
-
DC current
Pregunta 39
Pregunta
Which starting method provides the highest torque per ampere?
Respuesta
-
Auto-transformer
-
Across the line
-
Primary resistor
-
Wye-delta
Pregunta 40
Pregunta
What part of the wound rotor motor differs from that of a squirrel cage induction motor?
Respuesta
-
Stator
-
Rotor
-
End bells
-
Bearings
Pregunta 41
Pregunta
What size time delay fuse can be used on a 3 phase, 230V, auto transformer starting motor consuming 22.38 KW of power
Respuesta
-
70 amps
-
80amps
-
90 amps
-
100amps
Pregunta 42
Pregunta
What does increasing the frequency of the supply voltage to an induction motor cause?
Respuesta
-
Increased speed
-
Decreases speed
-
Increased torque
-
Decreased torque
Pregunta 43
Pregunta
A nine-lead dual voltage three-phase SCIM is connected in the lower voltage delta arrangement. Which terminals are connected to each other?
Respuesta
-
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
Pregunta 44
Pregunta
What is the ampacity of conductors feeding a 3 phase, 230V, SCIM, continuous duty motor rated at 20hp, 10hp, 1Hp, and 5Hp?
Respuesta
-
77.1A
-
88.3A
-
114.9A
-
116.6A
Pregunta 45
Pregunta
What meter is used to check the input phasing before installing a three-phase motor?
Respuesta
-
Phase rotation meter
-
Wattmeter
-
Motor rotation meter
-
Syncroscope
Pregunta 46
Pregunta
What effect does increasing the frequency of the supply have on the speed of the rotating magnetic field?
Respuesta
-
Increases
-
Decreases
-
No change
-
Changes direction
Pregunta 47
Pregunta
How does the starting current of a split phase motor compare to its full load current?
Respuesta
-
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
Pregunta 48
Pregunta
What information is required to size the overload protection of a 15Hp l, 600V, three-phase motor?
Respuesta
-
HP & FLA
-
SF AND FLA
-
V and FLA
-
Wire size and SF
Pregunta 49
Pregunta
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?
Respuesta
-
75.6%
-
90.8%
-
110%
-
157%
Pregunta 50
Pregunta
Which variables are identified by the motor service factor when considering the maximum continuous permissible load?
Respuesta
-
Voltage and amps
-
Voltage and frequency
-
Amps and frequency
-
RPM and voltage
Pregunta 51
Pregunta
A synchronous motor has a lagging power factor. How is the corrected?
Respuesta
-
Over excite the field
-
Add a capacitor
-
Increase the load reduce the load
-
Reduce the load
Pregunta 52
Pregunta
Which 3 phase motor provides maximum starting torque?
Respuesta
-
Capacitor run
-
Capacitor start
-
Induction run
-
Resistance run
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