PowerEngineeringThirdClassTestOld3rdCMLM8Try1-51动力工程三级考试试题试卷

Section2Lceture8Try:1

(2)1.Question=28109

Whenaloopofcurrentcarryingconductorisplacedinamagneticfieldthewireloopwill:

a.Turnclockwise

b.Generateacurrent

c.Haveatorqueproducedonit

d.Turnbackwards

(2)2.Question=28227

Thegeneratorisgenerallyofanopentypeconstructionsothatit:

a.Iseasytoclean

b.Hasabetterheatingeffect

c.Haseasyaccessforobservationandcleaning

d.Islighter

(2)3.Question=28405

Ina"growler"testaemfissuppliedtothegrowlercoil.

a.Directcurrent

b.Alternatingcurrent

c.Pulsatingdirectcurrent

d.Electrochemical

(2)4.Question=28415

Shortedoropencircuitcoilsusuallyrequirethearmaturetobe:

a.Discarded

b.Rewound

c.Reversed

d.Grounded

(2)5.Question=28217

Inalapwindingthetwoendsofonecoilareattachedtoadjacentcommutatorbars.

TorF

(2)6.Question=28301

AlloperatingDCmachinesexhibitbothageneratoractionandamotoraction.

TorF

(2)7.Question=28509

Seriesgeneratorfieldshavecomparativelyfewturnsofheavywire.

TorF

(2)8.Question=28510

Inaseriesgeneratorno-loadcharacteristicisrising.

TorF

(2)9.Question=28611

InaDCmotor,insertingextraresistanceintheshuntfieldcircuitbymeansofaregulating

rheostat,reducestheexcitationcurrentandflux,thusdecreasingspeed.

TorF

(2)10.Question=28118

Inagenerator,thedirectionoftheinducedemfcanbe

determinedbyapplyingFleming'sHandRule.

(2)11.Question=28624

Shuntmotorsareusedwhereapproximately

speedistobemaintainedbetweennoloadandfull-load.

(4)12.Question=28318

ThemainsourcesoflossinDCmachinesarelossesdueto:

1.Heatingofthearmatureandfieldconductors

2.Hysteresisandeddycurrentlosses

3.Lossesduetofrictionatbearingsandbrushes

4.Windageandfrictionlosses

a.1,2

b.2,4

c.2,3,4

d.1,2,3,4

Section2Lceture8Try:1

QuestionCorrect

NumberAnswer

1.1C

2.1C

3.1B

4.1B

5.1T

6.1T

7.1T

8.1F

9.1F

10.1right

11.1constant

12.1D

Section2Lceture8Try:2

(2)1.Question=28239

Withreferencetoanelectricalmachine,neutralaxishasthemeaningof:

a.Apositionwheretherotorisatrest

b.Apositionwherethebrushescauseminimumsparking

c.Apositionwherethebrushescausemaximumsparking

d.Apositionwheretherotorreversesmotion

(2)2.Question=28306

Armaturereactionthemainfield.

a.Increases

b.Decreases

c.Reverses

d.Distorts

(2)3.Question=28522

Intheovercompoundedgenerator:

a.Full-loadvoltageishigherthanno-loadvoltage

b.Full-loadvoltageislessthannoloadvoltage

c.Thespeedwillalwaysbelowerthanthelevelcompoundedgenerator

d.Noneoftheabove

(2)4.Question=28619

WherealargestartingtorqueisofprimeimportancetheDCmotortousewouldbe:

a.Series

b.Shunt

c.Compound

d.Cumulativecompound

(2)5.Question=28615

DCmotorsarerestrictedtoastartingcurrentofaboutpercentoffullloadcurrent.

a.50

b.100

c.150

d.200

(2)6.Question=28217

Inalapwindingthetwoendsofonecoilareattachedtoadjacentcommutatorbars.

TorF

(2)7.Question=28406

Inahealthlyarmaturebeingtestedona"growler"theemfinducedinonehalfofthe

winding

willbeequaltoandoppositetotheemfinducedintheotherhalfandsomaximumcurrent

willflowinthearmature.

TorF

(2)8.Question=28509

Seriesgeneratorfieldshavecomparativelyfewturnsofheavywire.

TorF

(4)9.Question=28116

Thetwomaineffectsoractionsthatrequireexplanationinordertounderstand

DCmachines,aretheactionandtheaction.

(2)10.Question=28117

Theunitofdensityisthetesla.

(2)11.Question=28319

InDCmachines,constantlossesareindependentofandconsist

ofexcitationcopperlosses,ironlosses,andwindageandfrictionlosses.

(4)12.Question=28418

Twotestsoftenusedtodetectproblemsinthearmaturewindingarethe:

1.Noloadtest

2.Bartobartest

3.Fullloadtest

4.Growertest

2,3

3

4

Section2Lceture8Try:2

QuestionCorrect

NumberAnswer

1.1B

2.1D

3.1A

4.1A

5.1C

6.1T

7.1F

8.1T

9.1generator

9.1motor

9.2generator

9.2motor

10.1flux

11.1load

12.1D

Section2Lceture8Try:3

(2)1.Question=28237

Thedisplacementbetweenthecentersofadjacentpolesinanarmatureiscalled:

a.Onepolepitch

b.360electricaldegrees

c.180geometricaldegrees

d.90electricaldegrees

(2)2.Question=28503

Theseparatelyexcitedgeneratorhasaloadcharacteristic:

a.Rising

b.Level

c.Falling

d.Series

(2)3.Question=28615

DCmotorsarerestrictedtoastartingcurrentofaboutpercentoffullloadcurrent.

a.50

b.100

c.150

d.200

(2)4.Question=28509

Seriesgeneratorfieldshavecomparativelyfewturnsofheavywire.

TorF

(2)5.Question=28302

Inthecaseofamotor,theemfinducedinthearmatureis

alwaysmorethanandopposedtotheappliedemf.

TorF

(2)6.Question=28421

TheDCmachine,becauseofits,brushesandbrushriggingis

particularlyvunerabletodirt,grease,moisture,andcorrosiveatmospheres.

(2)7.Question=28118

Inagenerator,thedirectionoftheinducedemfcanbe

determinedbyapplyingFleming'sHandRule.

(4)8.Question=28228

Therearetwomaintypesofarmaturewinding;thewindingandthe

_______winding.

(4)9.Question=28116

Thetwomaineffectsoractionsthatrequireexplanationinordertounderstand

DCmachines,aretheactionandtheaction.

(4)10.Question=28318

ThemainsourcesoflossinDCmachinesarelossesdueto:

1.Heatingofthearmatureandfieldconductors

2.Hysteresisandeddycurrentlosses

3.Lossesduetofrictionatbearingsandbrushes

4.Windageandfrictionlosses

a.1,2

b.2,4

c.2,3,4

d.1,2,3,4

(4)11.Question=28430

Incheckingforfaultsinthearmatureofadirectcurrent

machine,twotestsstandoutasmostprominent.

1.Noloadtest

2.Bartobartest

3.Fullloadtest

4.Growlertest

a.2,4

b.1,2,3

c.2,3

d.1,4

(4)12.Question=28610

Speedcontrolisusuallyrestrictedtomotors:

1.Series

2.Shunt

3.Residual

4.Compounded

a.1,2

b.1,3

c.1,4

d.2,3

e.3,4

f.2,4

Section2Lceture8Try:3

QuestionCorrect

NumberAnswer

1.1A

2.1C

3.1C

4.1T

5.1F

6.1commutator

7.1right

8.1lap

8.1wave

8.2lap

8.2wave

9.1generator

9.1motor

9.2generator

9.2motor

10.1D

11.1A

12.1F

Section2Lceture8Try:4

(2)1.Question=28103

Magnetomotiveforce(M.M.F.)istheproductoffluxand:

a.Voltage

b.Reluctance

c.Current

d.Resistance

(2)2.Question=28110

Ifaconductorismovedrelativetoamagneticfieldsoasto"cut"the

magneticfluxthenanwillbeinducedintheconductor.

a.emf

b.Current

c.Reluctance

d.Backemf

(2)3.Question=28239

Withreferencetoanelectricalmachine,neutralaxishasthemeaningof:

a.Apositionwheretherotorisatrest

b.Apositionwherethebrushescauseminimumsparking

c.Apositionwherethebrushescausemaximumsparking

d.Apositionwheretherotorreversesmotion

(2)4.Question=28309

Interpolesareconnectedinserieswiththe:

a.Fieldcoils

b.Load

c.Armature

d.Fieldpoles

(2)5.Question=28416

MostfaultsthatoccurinDCmachinestendtobeassociatedwiththe:

a.Stator

b.Frame

c.Leads

d.Armaturewinding

(2)6.Question=28503

Theseparatelyexcitedgeneratorhasaloadcharacteristic:

a.Rising

b.Level

c.Falling

d.Series

(2)7.Question=28505

Themannerinwhichtheterminalvoltagevarieswithavaryingloadcurrentiscalledthe:

a.Percentagevoltageregulation

b.Externalcharacteristic

c.Internalcharacteristic

d.No-loadcharacteristic

(2)8.Question=28613

Inashuntmotortorqueisproportionalto:

a.Armaturecurrent

b.Thesquareofthearmaturecurrent

c.Thelengthofthearmature

d.Thediameterofthearmature

(2)9.Question=28401

Short-circuitedcoilscausesparkingatthebrushes.

TorF

(2)10.Question=28202

ThearmatureofaDCgeneratoriswrappedwithfieldwindings.

TorF

(2)11.Question=28612

TorqueproducedbyaDCmotorisproportionaltobothfieldfluxandarmaturecurrent.

TorF

(4)12.Question=28321

InDCmachinesthetotallossesarethesumofthe

and

_________________________losses.

Section2Lceture8Try:4

QuestionCorrect

NumberAnswer

1.1B

2.1A

3.1B

4.1C

5.1D

6.1C

7.1B

8.1A

9.1T

10.1F

11.1T

12.1constant

12.1variable

12.2variable

12.2constant

Section2Lceture8Try:5

(2)1.Question=28105

Theunitofmagneticfluxisthe:

a.Weber

b.Tesla

c.Henry

d.Squaremetre

(2)2.Question=28103

Magnetomotiveforce(M.M.F.)istheproductoffluxand:

a.Voltage

b.Reluctance

c.Current

d.Resistance

(2)3.Question=28206

TheyokeinaDCmachineisusuallymadeof:

a.Steel

b.Copper

c.Aluminum

d.Insulation

(2)4.Question=28429

Theaccumulationofdirtanddustcollectingonelectricalmachineryeffectivelyformsa:

a.Protectivecoatingagainstrust

b.Thermalblanket

c.Negativeground

d.Noneoftheabove

(2)5.Question=28401

Short-circuitedcoilscausesparkingatthebrushes.

TorF

(2)6.Question=28508

Seriesgeneratorsarecommonlyusedbecausetheiroutput

voltageisconstantwithvaryingloadcurrent.

TorF

(2)7.Question=28511

Inacompoundedgeneratortheloadcurrentandgenerated

voltageincreaseuntilmagneticsaturationofthepolesisreached.

TorF

(2)8.Question=28608

Withaseriesmotortheloadmustbefastenedtothemotor

soitcannoteasilybecomedisconnected.

TorF

(2)9.Question=28319

InDCmachines,constantlossesareindependentofandconsist

ofexcitationcopperlosses,ironlosses,andwindageandfrictionlosses.

(2)10.Question=28229

Thepositionofminimumatthebrushesiscalledtheneutralaxis.

(2)11.Question=28320

InDCmachines,variablelosseswithloadandconsistofthearmaturecopperloss.

(4)12.Question=28610

Speedcontrolisusuallyrestrictedtomotors:

1.Series

2.Shunt

3.Residual

4.Compounded

a.1,2

b.1,3

c.1,4

d.2,3

e.3,4

f.2,4

Section2Lceture8Try:5

QuestionCorrect

NumberAnswer

1.1A

2.1B

3.1A

4.1B

5.1T

6.1F

7.1F

8.1T

9.1load

10.1sparking

11.1increase

12.1F

Section2Lceture8Try:6

(2)1.Question=28111

Amagneticfieldisalwaysconsideredtotravelfrom:

a.Positivetonegative

b.Negativetopositive

c.Northtosouth

d.Southtonorth

(2)2.Question=28102

Inamagneticcircuit,themagneticfluxistheequivalentof

electricinanelectriccircuit.

a.Voltage

b.Reluctance

c.Current

d.Resistance

(2)3.Question=28236

Withregardtotheassembledarmaturecore,it:

a.Iswrappedwithfieldwindings

b.Hasaxialslotsarounditsperiphery

c.Contactsthebrushes

d.Ismadeofhard-drawncopperbars

(2)4.Question=28215

Thedisplacementbetweenthecentersofadjacentpolesinanarmatureis:

a.Onepolepitch

b.360electricaldegrees

c.180mechanicaldegrees

d.90electricaldegrees

(2)5.Question=28308

Interpolescarrycurrent.

a.Field

b.Load

c.Flux

d.Armature

(2)6.Question=28407

Thespringcompression,forcarbonbrushesinindustrialelectricalmachinesshouldbe:

a.1.5kPa

b.15.0kPa

c.150.0kPa

d.0.15kPa

(2)7.Question=28519

ADCgeneratorisaDCmachinedrivenbya:

a.DCsourceofelectricity

b.Primemover

c.Qualifiedperson

d.Noneoftheabove

(2)8.Question=28307

Theamountofarmaturereactiondoesnotvarywithload.

TorF

(2)9.Question=28514

Ashortcircuitshuntallowsforamorecompactmachine.

TorF

(2)10.Question=28404

Whentestinganarmaturea"bartobar"testisbetterthana"growler"test.

TorF

(2)11.Question=28624

Shuntmotorsareusedwhereapproximately

speedistobemaintainedbetweennoloadandfull-load.

(4)12.Question=28616

ThethreepointstarterforDCmotorshasconnectionsfor:

1.Line

2.Positive

3.Negative

4.Field

5.Armature

L2，4

a.245

b.L3,45

c3,

dL23

4

234,

et.L5

Section2Lceture8Try:6

QuestionCorrect

NumberAnswer

1.1C

2.1C

3.1B

4.1A

5.1D

6.1B

7.1B

8.1F

9.1F

10.1F

11.1constant

Section2Lceture8Try:7

(2)1.Question=28102

Inamagneticcircuit,themagneticfluxistheequivalentof

electricinanelectriccircuit.

a.Voltage

b.Reluctance

c.Current

d.Resistance

(2)2.Question=28239

Withreferencetoanelectricalmachine,neutralaxishasthemeaningof:

a.Apositionwheretherotorisatrest

b.Apositionwherethebrushescauseminimumsparking

c.Apositionwherethebrushescausemaximumsparking

d.Apositionwheretherotorreversesmotion

(2)3.Question=28209

Thearmaturecoreismadeof:

a.Copper

b.Coppperlaminations

c.Hardsteellaminations

d.Softironlaminations

(2)4.Question=28620

Wherehighstartingtorquesarerequiredbuttherunningload

maybesmalltheDCmotortousewouldbe:

a.Series

b.Shunt

c.Compound

d.Undercompounded

(2)5.Question=28602

InashuntDCmotorthefieldisconnectedto:

a.Avariablevoltage

b.Thearmaturecurrent

c.Theconstantvoltagesupply

d.Thearmatureconductors

(2)6.Question=28409

Over-lubricationissometimesworsethanlackoflubrication.

TorF

(2)7.Question=28401

Short-circuitedcoilscausesparkingatthebrushes.

TorF

(2)8.Question=28511

Inacompoundedgeneratortheloadcurrentandgenerated

voltageincreaseuntilmagneticsaturationofthepolesisreached.

TorF

(2)9.Question=28121

Theunitofmagneticfluxistheweber.

TorF

(2)10.Question=28310

Constantlossesaredependantonload.

TorF

(2)11.Question=28319

InDCmachines,constantlossesareindependentofandconsist

ofexcitationcopperlosses,ironlosses,andwindageandfrictionlosses.

(4)12.Question=28520

Thethreebasicwaysinwhichaself-excitedgeneratorcanbeconnectedareclassifiedas:

1.Shuntgenerator

2.Compoundgenerator

3.Seriesgenerator

4.Parallelgenerator

14

a.23,4

b.132,4

c1

23

d.

Section2Lceture8Try:7

QuestionCorrect

NumberAnswer

1.1C

2.1B

3.1D

4.1C

5.1C

6.1T

7.1T

8.1F

9.1T

10.1F

11.1load

12.1D

Section2Lceture8Try:8

(2)1.Question=28109

Whenaloopofcurrentcarryingconductorisplacedinamagneticfieldthewireloopwill:

a.Turnclockwise

b.Generateacurrent

c.Haveatorqueproducedonit

d.Turnbackwards

(2)2.Question=28203

Theairgapsbetweenthepolesandthearmatureare:

a.Filledwithinsulation

b.Subjecttosparking

c.Increasedwithspeed

d.Keptcomparativelysmall

(2)3.Question=28209

Thearmaturecoreismadeof:

a.Copper

b.Coppperlaminations

c.Hardsteellaminations

d.Softironlaminations

(2)4.Question=28317

Awayofovercomingarmaturereactionisby:

a.Placingthebrushesattheairgaps

b.FeedingACcurrentintothebrushes

c.Insertinginterpolesbetweenthemainpoles

d.Heatingthebrushesabovethetemperatureofthe

armatureconductors

(2)5.Question=28429

Theaccumulationofdirtanddustcollectingonelectricalmachineryeffectivelyformsa:

a.Protectivecoatingagainstrust

b.Thermalblanket

c.Negativeground

d.Noneoftheabove

(2)6.Question=28524

Excitationoftheshuntfieldiscontrolledby:

a.Aregulatingrheostat

b.Amechanicalgovernor

c.Aconverter

d.Alongshunt

(2)7.Question=28620

Wherehighstartingtorquesarerequiredbuttherunningload

maybesmalltheDCmotortousewouldbe:

a.Series

b.Shunt

c.Compound

d.Undercompounded

(2)8.Question=28509

Seriesgeneratorfieldshavecomparativelyfewturnsofheavywire.

TorF

(2)9.Question=28302

Inthecaseofamotor,theemfinducedinthearmatureis

alwaysmorethanandopposedtotheappliedemf.

TorF

(2)10.Question=28120

Ifthecurrentintheconductorisreversed,orifthedirectionofthemain

fieldisreversed,thentheforceontheconductorwillbereversed.

TorF

(2)11.Question=28611

InaDCmotor,insertingextraresistanceintheshuntfieldcircuitbymeansofa

regulatingrheostat,reducestheexcitationcurrentandflux,thusdecreasingspeed.

TorF

(2)12.Question=28421

TheDCmachine,becauseofits,brushesandbrushriggingis

particularlyvunerabletodirt,grease,moisture,andcorrosiveatmospheres.

Section2Lceture8Try:8

QuestionCorrect

NumberAnswer

1.1C

2.1D

3.1D

4.1C

5.1B

6.1A

7.1C

8.1T

9.1F

10.1T

11.1F

12.1commutator

Section2Lceture8Try:9

(2)1.Question=28108

Whenacurrentcarryingconductorisplacedinamagneticfield,thefield

producedbytheconductorthemagneticfieldbetweenthepoles.

a.Addsto

b.Subtractsfrom

c.Distorts

d.Crosses

(2)2.Question=28109

Whenaloopofcurrentcarryingconductorisplacedinamagneticfieldthewireloopwill:

a.Turnclockwise

b.Generateacurrent

c.Haveatorqueproducedonit

d.Turnbackwards

(2)3.Question=28306

Armaturereactionthemainfield.

a.Increases

b.Decreases

c.Reverses

d.Distorts

(2)4.Question=28429

Theaccumulationofdirtanddustcollectingonelectricalmachineryeffectivelyformsa:

a.Protectivecoatingagainstrust

b.Thermalblanket

c.Negativeground

d.Noneoftheabove

(2)5.Question=28602

InashuntDCmotorthefieldisconnectedto:

a.Avariablevoltage

b.Thearmaturecurrent

c.Theconstantvoltagesupply

d.Thearmatureconductors

(2)6.Question=28513

Thecompoundgeneratorhasbothseriesandshuntfields.

TorF

(2)7.Question=28207

Thearmature,exceptinverysmallmachines,isgenerallymanufactured

fromcastorforgedsteellaminationsandboltedtotheyoke.

TorF

(2)8.Question=28422

Ifoneormoreturnsofthearmaturearethentheemfinduced

intheturnorturnswillcauseheavycurrentstoflowintheshortedturns.

(2)9.Question=28229

Thepositionofminimumatthebrushesiscalledtheneutralaxis.

(2)10.Question=28320

InDCmachines,variablelosseswithloadandconsistofthearmaturecopperloss.

(4)11.Question=28520

Thethreebasicwaysinwhichaself-excitedgeneratorcanbeconnectedareclassifiedas:

1.Shuntgenerator

2.Compoundgenerator

3.Seriesgenerator

4.Parallelgenerator

14

a.23&,4

bu.14

&2,

123

(4)12.Question=28616

ThethreepointstarterforDCmotorshasconnectionsfor:

1.Line

2.Positive

3.Negative

4.Field

5.Armature

L24

ab.2S3,5

44,

c15

,3.3

dL2

234

eM.45

:-L

Section2Lceture8Try:9

QuestionCorrect

NumberAnswer

1.1C

2.1C

3.1D

4.1B

5.1C

6.1T

7.1F

8.1short-circuited

8.1shortcircuited

9.1sparking

10.1increase

11.1D

12.1F

Section2Lceture8Try:10

(2)1.Question=28108

Whenacurrentcarryingconductorisplacedinamagneticfield,thefield

producedbytheconductorthemagneticfieldbetweenthepoles.

a.Addsto

b.Subtractsfrom

c.Distorts

d.Crosses

(2)2.Question=28203

Theairgapsbetweenthepolesandthearmatureare:

a.Filledwithinsulation

b.Subjecttosparking

c.Increasedwithspeed

d.Keptcomparativelysmall

(2)3.Question=28417

Dirtanddustwhichisallowedtocoverelectricalmachineryformsa:

a.Methodofstarting

b.Thermalblanket

c.Negativeground

d.Noneoftheabove

(2)4.Question=28416

MostfaultsthatoccurinDCmachinestendtobeassociatedwiththe:

a.Stator

b.Frame

c.Leads

d.Armaturewinding

(2)5.Question=28522

Intheovercompoundedgenerator:

a.Full-loadvoltageishigherthanno-loadvoltage

b.Full-loadvoltageislessthannoloadvoltage

c.Thespeedwillalwaysbelowerthanthelevelcompoundedgenerator

d.Noneoftheabove

(2)6.Question=28211

Thecommutatoristhemeansbywhichthecurrentisfedtoorfromthearmature

conductors.

TorF

(2)7.Question=28310

Constantlossesaredependantonload.

TorF

(2)8.Question=28307

Theamountofarmaturereactiondoesnotvarywithload.

TorF

(2)9.Question=28617

ADCmotormanualstarterhasstopandstartbuttons.

(2)10.Question=28118

Inagenerator,thedirectionoftheinducedemfcanbe

determinedbyapplyingFleming'sHandRule.

(2)11.Question=28527

Whenitisdesiredtocontroltheexcitationofaseriesfield,itcanbeaccomplished

byahighcurrentlowresistancerheostatcalleda.

(2)12.Question=28624

Shuntmotorsareusedwhereapproximately

speedistobemaintainedbetweennoloadandfull-load.

Section2Lceture8Try:10

QuestionCorrect

NumberAnswer

1.1C

2.1D

3.1B

4.1D

5.1A

6.1T

7.1F

8.1F

9.1F

10.1right

11.1diverter

12.1constant

Section2Lecture8Try: