维修电工基础知识(basic knowledge of maintenance electrician)

维修电工基础知识(basic knowledge of maintenance electrician)

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时间:2019-04-29

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1、维修电工基础知识(Basicknowledgeofmaintenanceelectrician)Basicknowledgeofelectricalengineeringandbasicknowledgeofmaintenanceelectrician.(1)resistivity--alsocalledresistancefactororspecificresistance.IsameasureoftheperformanceofconductivematerialwiththeletterP,saidthattheunits

2、ofohms*mm/squaremeters.Innumericalterms,equaltothematerialtodo1meterslong,crosssectionalareaof1squaremillimetersofwire,atthetemperatureof20Cresistance,thegreatertheresistivity,thelowerconductivity.Thephysicalquantityoftheresistivityofasubstancevarieswithtemperature,a

3、nditsvalueisequaltotheratiooftheincreaseinresistivitytotheoriginalresistivity,atanincreaseof1C,usuallyinalphaalpha,1/C.2,thetemperaturecoefficientofresistance,physicalquantitiesoftheelectricalresistivityofthematerialvarieswithtemperature,thetemperatureisincreasedwhen

4、the1Cvalueisequaltotheratioofincrease,theresistivityandtheoriginalresistivity,usuallyexpressedinlettersofalpha,unitis1/C.3,conductance----theabilityofanobjecttoconductelectriccurrentiscalledconductance.IntheDCcircuit,thenumericalvalueofresistanceisthereciprocalconduc

5、tance,withtheletterandsaid,inunitsofohms.4,conductivity--alsoknownasconductivitycoefficient,isalsoameasureofphysicalconductivityofagoodorbadphysicalquantity.Thesizeisthereciprocaloftheresistivityinnumericalterms.Theunitism/ohm*mmsquared.5electromotiveforce----thepote

6、ntialdifferencecausedbytheconversionofotherformsofenergyintoelectricenergyinacircuitiscalledelectromotiveforceorpotential.TheletterEstandsforvolts.6,self-whenthecurrentclosedloopchanges,thecurrentgeneratedbythecircuititselfthroughthefluxalsochanges,sointheloopwillals

7、oinducedelectromotiveforce,thisphenomenoniscalledselfinductancephenomenon,theinducedelectromotiveforcecalledelectromotiveforce.7mutualinductance-iftwocoilsareclosetoeachother,thefluxofthecurrentinthefirstcoilispartlyconnectedtothesecondcoil.Whenthecurrentinthefirstco

8、ilchanges,thenthefluxofthecoillinkwiththesecondcoilisalsochanged,andtheinducedelectromotiveforceisgeneratedinthesecondcoil.Thisphen

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