HP-6920B-Manual 电路图.pdf

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1、OPERATION AND SERVICE MANUAL MODEL6920B METER CALIBRATOR MANUFACTURINGCODEA - OPERATINGANDSERVICEMANUAL HEWLETT PACKARDHARRISON DIVISION RadioFans.CN 收音机爱 好者资料库 HEWLETTPACKARD CERTIFICATION TheHewlett-PackardCompanycertifiesthatthisinstrumentwas thoroughlytestedandinspectedandfound tomeetitspublishe

2、d specificationswhenitwas shipped fromthefactory.TheHewlett- PackardCompanyfurther certifiesthatitscalibrationmeasurements are traceable totheU.S.NationalBureauofStandardstotheextent allowedbytheBureauscalibration facility. WARRANTYANDASSISTANCE AllHewlett-Packardproductsarewarrantedagainstdefectsin

3、 materialsandworkmanship.Thiswarrantyapplies for oneyearfrom thedateofdelivery, or,inthecase ofcertainmajorcomponentslisted intheoperatingmanual,forthespecified period.Vewillrepairor replaceproductswhich provetobedefectiveduringthewarranty period.Nootherwarrantyis expressedorimplied. Wearenotliable

4、for consequential damages. ForanyassistancecontactyournearestHewlett-PackardSalesand Service Office.A.ddressesareprovidedatthebackofthismanual. RadioFans.CN 收音机爱 好者资料库 NOTICE These preliminary instructionsoresupplied to permit the t.!orliest possible deliveryofyour instrument.TheInfor- motionisnotas

5、completeasthotwhichwillbeincluded Inthe finoI yerson of the manual.Theattachedcordis provided tomakecertainthotthe final Operating and Servicing Manual for this instrument reaches the proper person.Please moil thiscordimmediatelyandwewill supply you with a copy of the complete manual05soon05 it beco

6、mes oyoilobie. HARRISONLABORATORIES .ISt.Of nwu.lCUv:p 100LOCUST .eNUEBERKELEYHEIGHTS.NEWJERSEYonn 464-1234.aCod.201TWX_2tll.464-2117 o, o .2 .!i .lI o o i. .2 Ji g 8 RadioFans.CN 收音机爱 好者资料库 BUSINESSREPLYMAIL FIIelMEIlMT:.;10BEPKI_FY HEIGHTS. N,J. QHARRISON LABORATORIES 100LOCUSTAVENUE BERKELEYHEIGH

7、TS,H. J.07922 Attn.PublicationsDept. - - - - - - - - - - - - - - - - - - - - - - - l L L L L L L l L L L L L L L L L L L OPERATION AND SERVICE MANUAL MODEL6920B METER CALIBRATOR MANUFACTURINGCODEA October,1965 1: .iL J J J J J J J J J J .1 . J J J J J J - *DConly. Powerfactorofload0.9to1.0inACRanges

8、. DCAccuracy:0.2%ofoutput.:1digit. ACAccuracy:0.4%ofoutput.:1digit. Lessthan0.001ohms. Greaterthan500megohms. Accuracyspecificationismetwithanyloadwithin thelistedoutputcapability. AC- 1VoltRilnqe: 100Range: OtherRanges: SPECIFICATIONS Input:105-125VAC,singlephase,58-62cps. Output:ACorDC. .01-IVto5A

9、 .1V-10VtolA IV-100Vto100 rna 10V-1000Vto10rna IjJ.Ci-1001JB*to500V 10jJ.Ci-1 rnato500V 100jJ.Ci-10rnato500V 1 rna-100 rnato50V 10rna -lAto5V 100ma-SAto.5V Grounding:Involtageranges,thenegativeterminalisgrounded. Incurrentranges,bothterminalsareoff-ground-loadmustbefloating. On10VACRange-minimumload

10、resistance5ohms 100VACRange-minimumloadresistance500ohms 1000VACRange-minimumloadresistance50Kohms OverloadProtection:Maybeshortedinvoltagerangesandopen-circuitedincurrent rangeswithoutdamage. LineRegulation:Theaccuracyspecificationswillbemetwithlinevoltagesfrom 105 to125VAC. OperatingTemperature:0t

11、o50oC. Accuracyspecificationmetat25+lOoCafter1hourwarm-upinstatic environment. OutputImpedance:DC-1VoltRange:Lessthan0.0005ohms. OtherRanges:Accuracyspecificationismetwithanyload withinthelistedoutputcapability. L l L l L L l l L l L l l l L L L L i J ,i :- J J J J J J J J J SECTION I GENERAL INFORM

12、ATION DESCRIPTION1-1 L 1-2TheModel6920Bisafeedback-regulatedpowersourceparticularlysuitedfor calibrationofmeters.Tencontinuouslyvariableoutputrangesareprovided,ranging from 1voltto1000voltsandfrom 100J.lato5Afulloutput.Allrangesprovideeither L .DCorACatthepower-linefrequency;however,the100J.larangei

13、snotcalibratedin .AC.Poweroutputcapabilityisfrom2.5wattsinthelOArangeto10wattsinthe10, 100,and1000voltranges.TheACoutput,whilehavingthesamewaveformasthein- putpowerline,iscontrolledtohavethecorrectaveragevalue.The3digitoutputdial iscalibratedintermsoftheRMSvalueofasinewave. L l L OPTIONAL EQUIPMENT

14、1-9COOLINGSYSTEM 1-7INSTRUMENT IDENTIFICATION 1-6A0.1ohmshuntisavailabletoextendthevoltagecapabilitiesdownwardtoinclude 1mvfulloutput,whenusedinconjunctionwiththecurrentrangesofthe692GB.When theshuntisused,thesourceimpedanceis0.1ohm. 1-5 1-8ThismanualappliesonlytotheModel692OB.Changesheetswillbesupp

15、lied whichincludeanydifferencesbetweenyourinstrumentandthismanual. L L L .l .1-3The6920Bisparticularlyusefulforproduction-linecheckingofmetersforaccu- racyandforstickingmovements.Inaddition,thewiderangeofoutputsallowscon- venientcheckingofmultimetersinthelaboratory.Compactconstruction,throughthe lus

16、eofallsemiconductorcircuitry,allowsforeasyportability. 1-4Built-incurrentandvoltagelimitingcircuitsprotectthe6920Bfromshortcircuit lloadsinvoltagerangesandopen-circuitloadsincurrentranges. L L L 1-10Thisinstrumentisconvectioncooledandrequiresnomaintenanceexceptforocca- sionaldusting.Adequatespacesho

17、uldbeprovidedaroundtheunittoallowfreecircula- tionofcoolingair. 1-11POWERCABLE 1-1 1-12A5-footthreeconductorpowercableissuppliedwiththeinstrumentterminatedin apolarizedthree-prongmaleconnectorrecommendedbytheNationalElectricalManufac- turersAssociation(NEMA).NEMArecommendsthattheinstrumentpanelandca

18、binetbe igrounded.AllHarrisonLaboratoriesinstrumentsareequippedwithapowercablewhich, Ii.whenpluggedintoanappropriatereceptacle,groundstheinstrument.Theoffsetpinon thepowercablethree-prongconnectoristhegroundpin. L1-14Topreservetheprotectionfeaturewhenoperatingtheinstrumentfrom atwo-prong outlet,usea

19、three-prongtotwo-prongadaptorandconnectthegreenpigtailonthe Ladaptortoground. . L SECTION II INSTALLATION 2-1INCOMINGINSPECTION 2-2Theinstrumentshouldbeunpackedandinspectedbothmechanicallyandelectrically uponreceipt.Observepackingmethodandretainpackingmaterialsuntilunithasbeen inspected.Mechanicalin

20、spectioninvolvescheckingforsignsofphysicaldamagesuch asscratchedpanelsurfaces,brokenknobs,etc.Ifdamageispresent,fileaclaimwith thecarrier.Theelectricalinspectioninvolvescheckingtheinstrumentagainstitsspeci- fications.SectionVincludesaperformancecheckwhichisanin-cabinetchecktoverify properinstrumento

21、peration.Itisrecommendedasanincominginspectiontest.Refer tothewarrantypageifthereisanyelectricalmalfunction. 2-3INSTALLATION 2-4Themetercalibratorisaportableinstrumentrequiringnopermanentinstallation. Itisonlynecessarytoconnectthepowercablesuppliedwiththeinstrumenttothepower inputandtheinstrumentisr

22、eadyforoperation. 2-5Thisinstrumentisaircooled.Sufficientspacetopermitfreeflowofcoolingair aroundtheinstrumentshouldbeconsideredwheninstalling.Itshouldnotbeusedinan areawherethetemperatureexceedsSOoC(l220F).Forratedaccuracy,thetemperature shouldbebetweenISoCand35 0 C (59 0 Fto9SoF). 2-6POWER REQUIRE

23、MENTS 2-7The6920Aoperateson115volts60cps.Theaverageinputcurrentwiththeoutput fullyloadedis1ampere. 2-8REPACKAGING FOR SHIPMENT 2-9Thefollowinglistisageneralguideforrepackaginganinstrumentforshipment.If youhaveanyquestions,contactyourauthorizedHarrisonLaboratoriessalesoffice. a.Usetheoriginalcontaine

24、r designedfortheinstrument.Ifanewcon- tainerisrequired,afoampackandcontainercanbeorderedfrom HarrisonLaboratories.Thestocknumberisgiveninthetableof replaceablepartsunderMiscellaneous. b.Wraptheinstrumentinheavypaperorplasticbeforeplacingitin theshippingcarton. c.Useplentyofpackingmaterialaroundallsi

25、desoftheinstrument andprotectthepanelwithcardboardstrips. d.Useheavycardboardcartonorwoodenboxtohousetheinstrument anduseheavytapeormetalbandstosealthecontainer. e.MarkthepackingboxwithFragile-DelicateInstrument,etc. 2-1 J J J J J J, J J J J J J J J J J ;,1 II L l L l L L L L L L L L l l L I. L NOTE

26、:IftheinstrumentistobeshippedtoHarrisonLaboratories forserviceorrepair,attachatagtotheinstrumentidentifyingthe ownerandindicatingtheserviceorrepairtobeaccomplished.In anycorrespondence,besuretoidentifytheinstrumentbymodel numberandserialnumber. 2-2 SECTIONIII OPERATION 3-1INTRODUCTION 3-2The6920Bisr

27、eadytouseasreceivedfromthefactory.Formaximumaccuracy, allowonehourafterturningontoallowtheinternaltemperaturetostabilize. 3-3Figure3-1describestheoperatingcontrolsandindicators. 3-4OPERATING CONTROLS 3-5OutputSwitch 3-6ThisdisconnectstheoutputterminalswhenitisinthecenterOFFposition.It shouldbeOFFwhe

28、nchangingloads,changingtherangeorfunctionswitchsettingand whenturningontheinstrument.Thisinsuresthatanyvoltagetransientswhichmayoccur atthesetimesdonotdamagetheloadortheoperator. 3-7Whenallothersettingsaremadeandtheloadconnected,theoutputswitchcanbe tippedtoeithertheON TESTortheON HOLDposition.Ineit

29、hercasepowerisnow beingfedintotheload.TheswitchwillreturntoOFFfromtheON TESTpositionas soonasfigurepressureisremoved.ItwillremainintheONHOLDpositionuntilmanu- allyreturnedtoOFF. 3-8AlwaysreturntheoutputswitchtoOFFbeforeremovingtheload.Thisisparticu- larlyimportantinthecurrentrangeswheredangerousvolt

30、ageswillexistiftheloadisre- movedwiththeoutputstillON. 3-9Thisswitchisalsousedtoresettheover-voltageprotectioncircuit.Seepara- graph3-28. 3-10OutputTerminals 3-11Thedevicetobecalibratedisconnectedtotheoutputterminals.InDCtheRed (HI) terminalispositive(conventionalcurrentflowoutoftheredterminal). 3-1

31、2InallvoltagerangestheBlack(LO)terminalisconnectedtothechassisandto earthgroundthroughthethree-wirepowercord. NOTE:Inallcurrentrangestheblackterminalisconnectedtoa pointinthecircuitwhichisasmuchasIvoltoffgroundpotential, dependingontheoutputdialsetting.DonotshunttheLOterminal toearthgroundwiththedev

32、icebeingcalibrated.Inaccuratere- sultsmaybeobtainedortheloadcouldbedamaged.Thereshould benoproblemofthiskinctwithnon-electronicorbattery-powered currentmeters.Ifline-operatedinstrumentsaretobecalibrated, seeparagraph3-29. 3-13FunctionSwitch CAUTION:DonotturnFUNCTIONSELECTORwhenOUTPUTSWITCHison. 3-1

33、J J J J J J J J J J J J J J J J 5.OutputIndicator:Brightlylitwhenpowerisbeingdeliveredatoutputterminals.Dims ifovervoltageprotectioncircuittrips.Outwhenoutputswitchisoff. RANGE 1 VOLTS OUTPUT0IMlICATOit 0lmVfIlllllCAlOlt OfF -.rWITII0IITPIIfswm:M roUSE I.snClVIPUTIWlTCWTO OfFfc:unnOII11llM1 ,.e:a-rr

34、.,. 3.lET?UIIIC11ON. MIlIlIAI a. u o U) I en 0 I!I, a:lLJ u z .J lLJ .Ja: -lLJ UlL. C/) LOO lLJ Ia: l).J u .Z (!)a: lLJ lL.lLJ xa: lLJlLJ lL.Q. 00 g : J J J J J J J J J J j J J J J J J J j L SECTION IV PRINCIPLES OF OPERATION I 1.4-1INTRODUCTION 4-3Aclosed-loopfeedbacksystemcontrolstheoutputbycompar

35、ingareferencevoltage, setbytheoutputdial,withasuitablemeasureoftheoutput.Thevoltagedifferenceis amplifiedandoperatestheseriesregulatortransistor. ,4-2The 6920 Bisamultiple-rangeAclDCpowersupplywhichissuitableforthecali- -brationofvoltageandcurrentmeters.AninvertercircuitisusedfollowingA DCseries reg

36、ulatortransistor.ThisprovidesACwhichisfedtoatransformer.Thevarioussecon- t darywindingsprovidecurrentupto5ampsandvoltageto1000volts.Thesquarewave .outputisrectifiedandfilteredandsuppliedtotheoutputterminals. L 4-8Theoutputoftheerroramplifierisdeliveredtothesynchronousdemodulator.In DCthisdemodulator

37、isbypassed,itsfunctionbeingtakenbytheoutputpowerrectifiers. InAC,thedemodulatorreversestheamplifierpolaritywhenevertheinverterswitches. 4-5Auxiliarycircuitsincludeaprotectivecurrentlimit,anover-voltagetripcircuit, andanamplifiertomaintaintheinvertertransformerinastateofDCbalance.Anoutput indicatorla

38、mpisusedtoshowthestateoftheover-voltagetrip. BLOCKDIAGRAM4-6 4-7Figure4-1showsanover-allblockdiagramoftheModel6920B.Theoutputsignal issampledbytherangedividertoobtainasignalwhichis1voltforfulloutput.Inthe voltagerangesthisisavoltagedivider,forexample1000:1inthe1000voltrange.In tcurrentrangesitisaser

39、iesmonitoringresistor;forexample,1000ohmsintheIma .range.Therangeresistorconfigurationsareshowninfigure4-2.Thissignalisfed backtotheinputamplifierwhereitiscomparedwithavariablereferencevoltage,setby LmeansoftheoutputwhichoperatesR4. L L4-4ACoperationissimilarwiththeexceptionthatanACreferenceisused.T

40、he rectifiersarebypassedatthesecondaryoftheoutputtransformerandasynchronousde- L .modulator,intheerroramplifier,keyedattheinverterfrequencyisusedtomaintain negativefeedbackduringbothhalvesoftheinvertercycle. l l t :4-9Thedemodulatorfeedsasignaltothepowerregulator.Heretheerrorsignalis .furtheramplifi

41、edandusedtocontrolaseriesregulatorpoweramplifier. 4-11Theoutputoftheseriesregulatorisappliedtoaninverterconsistingoftransistors Q14andQ15,whichisdrivensynchronouslywiththeACpowerline.IntheDCmodeof operationthisproducesasquarewavesignalwhichissuitableforapplyingtotheoutput transformer. L4-10INVERTER

42、L i.r4-12InAC,becausetheACreference,thesynchronousdemodulatorandtheinverterare allsynchronizedwiththeACpowerline,thesignalappliedtotheinverterappearsasa Lfull-waverectifiedsinusoidalwaveform.Afterpassingthroughtheinverterthedesired sinewaveisobtainedonthetransformerprimary. 4-1 l (IvSIGNAL FOR l!ULL

43、OUTPUTJ + :J a. :J o r- - - .- 0: 0 U :x: :x:t- U uw C/) C/)r- i(!) I C/) z C/)z .roo 0:r- 0 wo - w (!)z 0: LL UI-z- 0 Z et :x:!i I U :J o: WI- LL ir-, U:J 0: z -w t- :J 0C/) f -wetr- 1-.,._, (!) z etu Il:et - m 0 w w LL - /1 CURRENT IIIII , IOFFIIoTRANSFORMER mJL.oDCBALANCEI4!: L-:1=,-0AMPLIFIER DC

44、 FIG.4-1 FUNCTIONAL BLOCKDIAGRAM .IfaSll:1-ittaaw.Iii.theselevelscorrespond to1000VatlOrna,100Vat100ma,10VatlAand2Vat.SA. 4-17RANGESWITCH 4-19DC REFERENCE 4-13OUTPUT TRANSFORMER 4-16Thisswitchselectswhetherthetransformeroutputistoberectifiedornot.Inthe ACmodeofoperationtheoutputrectifiersarebypassed

45、.ItalsoselectstheACorDC reference,bypassesthesynchronousdemodulatorinDCandchangesthefeedbackloop equalizers. i . . ill L L L L L 4-22TheACreferencevoltageisobtainedbytakinganACsignalderivedfromtheAC I lineandcontrollingitsamplitudewithaphoto-resistor.TheACsoobtainedisaccur- atelyconvertedtoDC,propor

46、tionaltotheaverageAC.Thissignaliscomparedwith theDCreference.ADCamplifierconsistingoftransistorsQ1,Q3andQ5amplifiesthe erroranddrivesanincandescentlampwhichaffectsthephoto-resistorinsuchawayas torestoretheACreferencetothedesiredvalue.Ablockdiagramofthiscircuitappears infigure4-3. 4-23ACtoDCconversio

47、nisaccomplishedbyanAC-coupledfeedbackamplifiercontain- ingdiodesCR30andCR31whichdriveitsfeedbacknetwork.Thisconfigurationhasthe advantagethatchangesindioderesistancewithvoltageandtemperaturehavelittleeffect ontheaccuracyoftheACtoDCconversionprocess . 4-24BALANCEAMPLIFIER 4-25AnamplifierconsistingofQ

48、30andQ31isconnectedtosensetheaverageDCinthe transformerprimarybymeansofresistorsR46andR47asshowninfigure4-4.IfaDC unbalanceexists,theamplifieroutputisusedtomakecorrectioninthecircuittobalance theprimarycurrent.IntheDCmodeofoperationthetimingoftheinverterischangedin suchawayastomaketheONtimeofoneofth

49、etwoinvertertransistorsslightlylonger withrespecttotheother.InAC,thebalanceamplifieroutputchangestheDClevelof theACreferencesignalwhichhastheeffectofbalancingthetransformerDC. R46 , . L R47 TOREFERENCEINPUT FIG.4-4 TRANSFORMERDCBALANCE AMPLIFIER TOINVERTER DRIVECIRCUIT L L L l L oIOFFJ -)mJ .-.0_-,r oIOFF( oIT .-.0-. I 4-5 C27 Rl00 Rl0l l i . l L L - 4-26INVERTER 4-27Theinverterconsistsoftransistors014and015whi