servo valve calibrationWord下载.docx
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servo valve calibrationWord下载.docx
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crank"
modeforthecalibrationwithinlimitedtime.Pleaseguidemefortheproperandeffectivecalibrationofthedist.fuelsystem.
Thanks..
Replytothispost...
PostedbyBobJohnstonon19May,2013-7:
09pm
It'
sdifficultIknow,reallytheonlywaytocheckisdoa"
dummyfire"
withnosparkplugsandquicklycheckthefuelflowatacoupleofManualFSRpoints.Runatrendofthemajorcriteriaatthesametimeandyoucanthenreview.
GivethemachineabitofaCrankaftertestingandbeforefiringtogetridoftheexcessfuel.
CSA
on20May,2013-6:
23am
ESKAY,
Thisideaof"
calibratingservo-operateddevices"
onGE-designheavydutygasturbinesisa
HUGE
myth.It'
ssimply
notpossible
tocalibrateanythingotherthanLVDTfeedback.EvenwhenGEfieldpersonnelsaytheyare"
calibrating"
theSRVortheGCVortheIGVsortheLFBV(LiquidFuelBypassValvetheyare
NOT.
TheyareonlycalibratingtheLVDTfeedbackfromthosedevices.Thereiszero
effectontheservoortheservo-valveoutputstabilityafter"
calibration"
;
theonlythingthatchangesistheLVDTfeedbackcalibration.
Fullstop.
Period.
ssimplyimpossibletosendapositionreferencetoadevicethathasnopositionfeedbackandexpectthatdevicetogotosomeposition,orwhattheSpeedtronicbelievesthatpositiontobeifthereisnopositionfeedback.
So,don'
tbelieveeverythingyouhearpeoplesaywhoseemtobeknowledgeableaboutGESpeedtroniccontrolsystems,becausetheyquiteoftendon'
tsaywhattheymean,andtheyquiteoftendon'
tknowwhattheyaresaying.Especiallywhentheyaretalkingaboutelectro-hydraulicservo-valves.
Ifyouarehavingproblem(s)withcontrolofliquidfuel,telluswhattheproblem(s)are,whatyouhavedonetotroubleshoottheproblem,andwhattheresultsofyourtroubleshootingwere.Thenwecantrytohelpyouwithresolvingyourproblem,orwithunderstandingtheliquidfuelsystemanditscomponents.
AsBobJohnstonsays,ifyoudon'
thaveanACmotor-drivenAuxiliaryHydraulicPumpthenyouaregoingtohavetocranktheunittoestablishhydraulicpressure--justaswithanyotherhydraulically-operateddevice.
TherehavebeensomeverycreativepeoplewhohaveusedtheDCmotor-drivenHydraulicRatchetPumptoprovidehydraulicpressuretothehydraulicsystem,butittakessometemporarytubingre-work.AndIdon'
tbelievetheHydraulicRatchetPumpoutputisfilteredverywellsotherecanbecontaminationofservosand/orservofiltersifthat'
susedforthatpurposewithoutproperfiltration.Also,thepressureoftheHydraulicRatchetPumpisnotadjustableandislikelynotthesameastheMainHydraulicPump,noristheflow-rateoutputoftheHydraulicRatchetPumpanywherenearthatoftheMainHydraulicPump.Itworksforacrudecheckofsystemoperation,butforanythingmorethanthatitisnecessarytocranktheunittogetpressurefromtheAccessoryGear-drivenMainHydraulicPumpifthereisnoACmotor-drivenAuxiliaryHydraulicPump.
TheliquidfuelcontrolvalvesofmostGE-designheavydutygasturbinesaredesignedtocontrolflow-rateusingfeedbackfromtheliquidfuelflowdivider.Theflowcontrolvalveispositionedatwhateveropening/closingitneedstobeatinordertomakethescaledfeedbackfromthespeedpick-upsontheliquidfuelflowdividerequaltotheliquidfuelflow-ratereference(foraMarkVI,thatsignalnameisusuallyFQR,andtheflow-ratefeedbackisusuallyFQLorFQLMorFQLM1).
EvenforLFBVswithLVDTs,theLVDTsarejusttherefor"
stability"
themaincontrol"
loop"
fortheliquidfuelsystemisflow-rateusingtheliquidfuelflowdividerfeedback.
ToproperlycalibrateLVDTfeedbackitisnecessarytophysicallymeasurethepositionofthedevicewiththeLVDTs--somethingmostpeopleneverdoonGE-designheavydutygasturbineswhen"
LVDTfeedback.MostoftheLFBVsonnewerGEFrame5sdonothavevalvestemsorplugsthatarevisiblesoit'
snotevenpossibletoverifythepositionofthevalveplug.
Again,ifyouarehavingproblemswithliquidfueltelluswhattheyare,whatyou'
vedone,andwhattheresultsofwhatyou'
vedonewere.Ifyouonlyrunliquidfueloccasionallyandyouhavetroublestransferringfromgasfueltoliquidfuel,ortroublestartingonliquidfuelthentheLFBVisnottheproblem--norwouldthe"
oftheLVDTsontheLFBVbetheproblem.
on20May,2013-1:
41pm
Ithoughtwe'
dbeenoverthisbefore....
Nothinghaschangedsincethen.
Nothing.
on21May,2013-1:
33pm
DearCSA,
Thanksfordirectingmetotheoldthread,forthesameissueofcalibratingthe65FPservovALVE.
AsyouhavefurtherclarifiedthatthereisNOwaytocalibratethefunctionalityof65FPservo,otherthanrunningtheturbineindistillatemodeandandviewthetrendandvarioussignalsinsertedintothewatchwindowtoanalysetheproblem,ifany.Assuch,wehaveNOprobleminthedistillatefuelmodeoperation.Iwouldliketogettheknowledgeaboutcalibratingthedist.fuelservo,incase,ifitisrequired.Thanksfortheadviceandyouracknowledgement/quickresponse.
Wishingyou..Regards..
on22May,2013-12:
21pm
DearCSAsir,
Icouldnotfindtheanswerthrothe"
search"
facilityORearlierthreadsregardingmyclarificationonMk4servocalibration,whichwasrejectedbyoneofyourmoderator.
*******************************************************************
Moderator'
snote:
ThemoderatorsforCarenot
employedbyCSA.ThemoderatorsworkforC.CSAisoneof
themanyreadersofthisforumwhofreelygiveshisadvicetoothers.
Heandthenumerousotherforumreadersandparticipantsarewhoand
whatmakesthisforumpossible.
IFOLLOWEDTHEPROCEDUREGIVENINTHEMANUAL,butIhavecertainissues.OnthecalibrationdisplayforSRVANDGCV,whileGDAJisvaried,withL4X1-L4X-L3adj-L20FGX1-L3GCV(forGCV)-L3GRV(fortheSRV)-forcedto"
1"
withAUX.HydraulicoilpumpswitchedON.IfindtheSRVservovalvestrokingfromitsdatum(closed)positiontoitsfullopenpositionwithGDAJsetat-0.30andaboveandviceversa.WhereasforGCV,theSERVOdoesnotliftatall.IsittheJDAJhexa-decimalvalue,automaticallychangestoeither13OR12withtheFORCEENTERisactivatedORJDAJvaluechangeisNOTrequired.WhatmustbethevalueforLOCATELOWandLOCATEHIGH,normallysetfortheservo?
(forGCV/SRV).WhyitisNOTpossibletoholdtheSRVatanyfixedvalueofGDAJ?
WhereamIwrong?
Pleasehelpsolvetheprobleminservocalibration.
Iseekyourkindhelp/adviceatyourearliest,sir.
Thanks..Withregards..
on22May,2013-2:
28pm
Isenseyourfrustration.I,too,foracoupleofyearsasanewGEemployeewasunderthemistakenbeliefthatliquidfuelbypassvalves--indeed,anyservo-operateddeviceonaGE-designheavydutygasturbine--required"
calibration."
Itwasn'
tuntilIreallythoughtaboutandunderstoodwhatcalibrationis,inageneralsense,andwhatis--orcanbe--calibratedonaGE-designheavydutygasturbinewithservo-operateddevicesthatitreallybecamecleartome.
Iwasonlyreferringyoutoapreviouspostinwhichyouasked,essentially,thesamequestion:
Howto"
aservo,specificallyaservo-operatedliquidfuelbypassvalvewhichdoesNOThaveLVDTsforpositionfeedback.
Whenusingthe"
Calibrate"
featureofaSpeedtronicturbinecontrolsystemonaservo-operateddevice,the>
>
ONLY<
<
"
thing"
thatiscalibratedisLVDT
(position)
feedback.IFTHEREARENOLVDTs,THEN>
NOTHING<
CANBECALIBRATED.
Theservoisnot"
calibrated."
Thevalve(orIGVs)arenot"
OnlyLVDTfeedbackfromadevicewithanelectro-hydraulicservo-valveiscalibratedusingthe"
featureofaSpeedtronicturbinecontrolsystem.
RegardlessiftheSpeedtronicisaMarkIV,MarkV,MarkVI,orMarkVIe.
IftherearenoLVDTsontheservo-operateddevicethennothingcanbecalibrated.
"
Calibration"
ofaservo-operateddevicewithLVDTsforpositionfeedbackistheprocessofconvertingthevoltagefeedbackfromtheLVDT(s)toposition,inpercentofratedstroke(travel)ofthedevice(or,inthecaseofIGVs,degreeofangleofopening).
Ifthe0%strokeoccursat0.700VACRMSvoltagefeedback,andthe100%strokeoccursat3.500VACRMS(thevaluesareforexemplarypurposes
ONLY),thentheoffset(or"
zero"
)forthefeedbackvoltageis0.700VACRMS,andthegain(or"
span"
)forthefeedbackis0.028VACRMSperpercentstroke.TheSpeedtroniccalculatestheoffsetandgaininternallyafterdeterminingthevaluesduringacalibration;
thereisnooperatorortechnicianactionrequir
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