Kaitlyn Hickey
Quiz by , created more than 1 year ago

Quiz on ER-2031, created by Kaitlyn Hickey on 03/02/2018.

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Kaitlyn Hickey
Created by Kaitlyn Hickey almost 7 years ago
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ER-2031 block review

Question 1 of 52

1

What is the maximum number of trip coils required for a three phase motor?

Select one of the following:

  • 2

  • 3

  • 5

  • Not required

Explanation

Question 2 of 52

1

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?

Select one of the following:

  • Resistance-start induction-run

  • Squirrel-cage induction

  • Synchronous

  • Wound-rotor induction

Explanation

Question 3 of 52

1

What is the maximum time-delay fuse that can be used with a three-phase motor of the full load current?

Select one of the following:

  • 125%

  • 175%

  • 225%

  • 300%

Explanation

Question 4 of 52

1

How can locked rotor current be described?

Select one of the following:

  • 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

Explanation

Question 5 of 52

1

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?

Select one of the following:

  • 125%

  • 225%

  • 300%

  • 400%

Explanation

Question 6 of 52

1

What is the basic principle of operation for all three-phase motors?

Select one of the following:

  • A rotating magnetic field

  • DC field operation

  • Brushless field excitation

  • Maintenance

Explanation

Question 7 of 52

1

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?

Select one of the following:

  • 50-100 percent

  • 100-200 percent

  • 200-300 percent

  • 300-400 percent

Explanation

Question 8 of 52

1

What is the phase voltage of a three-phase 600 volt squirrel cage connected delta?

Select one of the following:

  • 208V

  • 347V

  • 600V

  • 750 V

Explanation

Question 9 of 52

1

What does the service factor reveal about the motor?

Select one of the following:

  • 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

Explanation

Question 10 of 52

1

What is the conduction called if one phase of a three-phase motor opens?

Select one of the following:

  • Double phasing

  • Single phasing

  • Triple phasing

  • Free running

Explanation

Question 11 of 52

1

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?

Select one of the following:

  • 75C

  • 90C

  • 110C

  • 125C

Explanation

Question 12 of 52

1

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?

Select one of the following:

  • Lugs

  • Polarity

  • Continuity

  • Rotation

Explanation

Question 13 of 52

1

What is the temperature rating of the conductors supplying a motor with a class H insulation rating?

Select one of the following:

  • 90C

  • 100C

  • 110C

  • 120C

Explanation

Question 14 of 52

1

What is the maximum feeder conductor ampacity required to supply a bank of three phase motor are: 96 A, 27A, and 156A

Select one of the following:

  • 279A

  • 318A

  • 337A

  • 303A

Explanation

Question 15 of 52

1

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

Select one of the following:

  • #1/0 AWG

  • #1 AWG

  • #400mcm

  • #2/0 AWG

Explanation

Question 16 of 52

1

What is the speed at 60 Hz of a 12 pole synchronous motor?

Select one of the following:

  • 120 rpm

  • 300rpm

  • 600 rpm

  • 1200rpm

Explanation

Question 17 of 52

1

In a wound rotor motor, the torque characteristic can be altered by?

Select one of the following:

  • Adding or removing external resistance

  • Adding and removing external inductance

  • Adding or removing external capacitance

  • Torque may not be altered

Explanation

Question 18 of 52

1

Three-phase motor windings are installed ____ electrical degrees apart from each other

Select one of the following:

  • 90

  • 120

  • 180

  • 270

Explanation

Question 19 of 52

1

What is the term used to describe the amount of torque required to pull the rotor into synchronous speed?

Select one of the following:

  • Cut-out torque

  • Cut-in torque

  • Pull-out torque

  • Pull-in torque

Explanation

Question 20 of 52

1

What is the term used to describe the angle between the centre of the stator pole and the centre is the rotor pole?

Select one of the following:

  • Torque angle

  • Angle of incidence

  • Phasing angle

  • Synchronous angle

Explanation

Question 21 of 52

1

What is the advantage of a synchronous motor?

Select one of the following:

  • Constant speed from no load to full load

  • Lower voltage starting

  • Can run on either AC and DC

  • Speed can be controlled

Explanation

Question 22 of 52

1

What size time-delay fuse is required for a three phase, 25hp, 600v, scim

Select one of the following:

  • 20 A

  • 30A

  • 15A

  • 40A

Explanation

Question 23 of 52

1

What meter is used to check phasing in a 3-phase motor when it is de-energized and out of service?

Select one of the following:

  • Clamp-on meter

  • Multimeter

  • Phase rotation meter

  • Phase sequence meter

Explanation

Question 24 of 52

1

What powers the field generation in a typical synchronous motor?

Select one of the following:

  • External resistor

  • External DC source

  • External AC source

  • External capacitors

Explanation

Question 25 of 52

1

The basic principle of all 3 phase motors for synchronous motor is?

Select one of the following:

  • Reluctance

  • Capacitance

  • Induction

  • Rotation

Explanation

Question 26 of 52

1

By checking leads T7, T8, T9 of a nine lead motor, an electrician can determine

Select one of the following:

  • The voltage of the motor

  • The FLA of the motor

  • The winding connection (wye or delta)

  • The service factor of the motor

Explanation

Question 27 of 52

1

What are synchronous motor mainly used for

Select one of the following:

  • Fan

  • Pumps

  • Compressors

  • All of the above

Explanation

Question 28 of 52

1

The insulation class rating of a totally enclosed non-ventilated motor operating at 90 degrees is

Select one of the following:

  • Type A

  • Type F

  • Type B

  • Type H

Explanation

Question 29 of 52

1

In dual voltage 3 phase motors, the leads are connected in ____ for low voltage and in ____ for high voltage

Select one of the following:

  • Parallel-series

  • Series-parallel

  • Delta-wye

  • Wye-delta

Explanation

Question 30 of 52

1

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.

Select one of the following:

  • 115%

  • 150%

  • 200%

  • 300%

Explanation

Question 31 of 52

1

Which markings are used to designate the rotor terminals of a wound rotor motor?

Select one of the following:

  • L1 L2 L3

  • F1 F2 F3

  • M1 M2 M3

  • T1 T2 T3

Explanation

Question 32 of 52

1

In order to not trip, what is the maximum percent rating for an instaneous trip circuit breaker of an AC motor?

Select one of the following:

  • 700%

  • 900%

  • 1300%

  • 1500%

Explanation

Question 33 of 52

1

What is the speed of rotation of the magnetic field called in a three-phased motor?

Select one of the following:

  • Magnetic

  • Slip

  • Synchronous

  • Rotor

Explanation

Question 34 of 52

1

What is the proper rating of a time-delay fuse for a 230v, 22.38 KW, auto-transformer start continuous duty motor

Select one of the following:

  • 100Amp

  • 125Amp

  • 150Amp

  • 225Amp

Explanation

Question 35 of 52

1

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?

Select one of the following:

  • 1700 RPM

  • 1900 RPM

  • 2000 RPM

  • 2100 RPM

Explanation

Question 36 of 52

1

What is the purpose of the centrifugal switch in split phase motor?

Select one of the following:

  • 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

Explanation

Question 37 of 52

1

What is the speed at which the centrifugal switch of a split phase motor will operate?

Select one of the following:

  • 60%

  • 65%

  • 70%

  • 75%

Explanation

Question 38 of 52

1

How is the rotor of a 15 hp synchronous motor operating on line voltage excited?

Select one of the following:

  • AC voltage

  • Induced magnetic field

  • AC line voltage

  • DC current

Explanation

Question 39 of 52

1

Which starting method provides the highest torque per ampere?

Select one of the following:

  • Auto-transformer

  • Across the line

  • Primary resistor

  • Wye-delta

Explanation

Question 40 of 52

1

What part of the wound rotor motor differs from that of a squirrel cage induction motor?

Select one of the following:

  • Stator

  • Rotor

  • End bells

  • Bearings

Explanation

Question 41 of 52

1

What size time delay fuse can be used on a 3 phase, 230V, auto transformer starting motor consuming 22.38 KW of power

Select one of the following:

  • 70 amps

  • 80amps

  • 90 amps

  • 100amps

Explanation

Question 42 of 52

1

What does increasing the frequency of the supply voltage to an induction motor cause?

Select one of the following:

  • Increased speed

  • Decreases speed

  • Increased torque

  • Decreased torque

Explanation

Question 43 of 52

1

A nine-lead dual voltage three-phase SCIM is connected in the lower voltage delta arrangement. Which terminals are connected to each other?

Select one of the following:

  • 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

Explanation

Question 44 of 52

1

What is the ampacity of conductors feeding a 3 phase, 230V, SCIM, continuous duty motor rated at 20hp, 10hp, 1Hp, and 5Hp?

Select one of the following:

  • 77.1A

  • 88.3A

  • 114.9A

  • 116.6A

Explanation

Question 45 of 52

1

What meter is used to check the input phasing before installing a three-phase motor?

Select one of the following:

  • Phase rotation meter

  • Wattmeter

  • Motor rotation meter

  • Syncroscope

Explanation

Question 46 of 52

1

What effect does increasing the frequency of the supply have on the speed of the rotating magnetic field?

Select one of the following:

  • Increases

  • Decreases

  • No change

  • Changes direction

Explanation

Question 47 of 52

1

How does the starting current of a split phase motor compare to its full load current?

Select one of the following:

  • 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

Explanation

Question 48 of 52

1

What information is required to size the overload protection of a 15Hp l, 600V, three-phase motor?

Select one of the following:

  • HP & FLA

  • SF AND FLA

  • V and FLA

  • Wire size and SF

Explanation

Question 49 of 52

1

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?

Select one of the following:

  • 75.6%

  • 90.8%

  • 110%

  • 157%

Explanation

Question 50 of 52

1

Which variables are identified by the motor service factor when considering the maximum continuous permissible load?

Select one of the following:

  • Voltage and amps

  • Voltage and frequency

  • Amps and frequency

  • RPM and voltage

Explanation

Question 51 of 52

1

A synchronous motor has a lagging power factor. How is the corrected?

Select one of the following:

  • Over excite the field

  • Add a capacitor

  • Increase the load reduce the load

  • Reduce the load

Explanation

Question 52 of 52

1

Which 3 phase motor provides maximum starting torque?

Select one of the following:

  • Capacitor run

  • Capacitor start

  • Induction run

  • Resistance run

Explanation

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