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How Auxiliary Contactors mounting may result into Mal-operation & hence tripping of Equipment

Case Study of Auxiliary Contactors mounting may result into Mal-operation & hence tripping of Equipment

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How Auxiliary Contactors mounting may result into Mal-operation & hence tripping of Equipment

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  1. ISO 9001:2015 ISO 45001:2015 (OH & S) Certified Company Case Study How Auxiliary Contactors mounting may result into Mal-operation & hence tripping of Equipment www.systemprotection.in +91-265-2225137

  2. Hello Friends / Sirs, Panelmanufacturermaysay, nothingis wrong, butasamaintenanceengineer, whatwehavenoticeisthatitmaybethe wrongwayinthelongerperiod. Why? ManyofyouhaveseenpositionofAuxiliary contactorinsideyourpanelasshownin BelowPic-1 & 2. Wearegoingtoexplainit. (Tryingitin simpleway) Butisittherightwayofputtingittogether? Pic-1 Pic-2 www.systemprotection.in +91-265-2225137

  3. Obviously, itisnotnecessarythatallthe contactorsareONatsametimeanditwill neverbe. Butyes2-3adjacentcontactors canbeONsimultaneously. Thiscase happenedinMay’2015. HODsir ofthatplantadvisedtocreate somespacebetweenalltheauxiliary contactorsinoneHTMotorpaneland comparethetemperaturewiththosewith nospaceinbetween. Thiswas HODsir past experiencesregardingPower & Auxiliary Contactors. Aboveauxiliarycontactorswereplacedin oneHTPanelwhichwasusedtostartaMill (Motor) inaprocessindustry. After3yearsof commissioningofplantoneHTpanelgot tripped. Andwhatengineerfound, thatcoil ofAuxiliarycontactorwasburntandhence itwasnotpickingupandthatfeedback signalwasnotgoingtocontrolroom, ultimatelyresultingintotrippingofthat MotorandhencethatsectionofthePlant. Andin3-4daysteamfoundtherootcause. ThetemperaturedifferenceonAux contactorsbetween2panelswasaround5- 6degrees. Actually, theminorheatwhich wasgeneratedwhencontactorwas ON, was notabletodissipateproperlyduetono spacebetweenAuxcontactors, anddueto thisheatgeneratedbythecontactorswere accumulatedthereonlyandinthelongrun contactorcoilwasburningorcontactor failing. Maintenanceteamreplaceditwithspare Auxcontactor, that’swhatnormallywedo asamaintenanceengineersothatthe breakdowntimedecreases. Theytryto foundoutwhatcouldhavehappened, but didn’tgetitinfirsttimeexcepttheAux contactorfailedwasheated. (*Note – therecouldbemanyotherreasons fortemperaturedifferenceinpanels) TheycheckedthesamewithOtherHT paneltooandyestemperatureon contactorsinPanelwithsomespaces betweenAuxcontactorswasonlowerside comparedtothosewithnospacebetween AuxContactor. Thesamewasimplemented acrossplant, asperthespaceavailable. Sameproblemoccurs2timesmorewithin 6-7monthsinotherPanelofHTmotorand againplantgottripped, reasonfoundtobe sameasabovecoilfailedandAuxcontactor foundheated, butthistimetheyhaveto findtherootcausestoo. Aftercheckingall thethingsfromlooseconnectionsto earthingtheydidn’tfindanythingwrongin wiringoranyotherabnormalities. Thentheydecidedtochecktemperatureall ofsuchmotor, transformerandfeeder panelswithtemperatureGun. Yes, therewe foundsomedifferences. TemperatureonAuxiliarycontactorwas highersidecomparedtootherpartsof controlcabinetinHTpanel. Andonfurther analysistheyfoundthattemperatureof4-5 contactorswhichwere ON wereonhigher side. Maintenanceteamweregettingcloser tofindtherootcause. www.systemprotection.in +91-265-2225137

  4. Pic-3 Pic-4 Also, everyplanthasitsownspaceproblemsinHTpanels, butwhatweasamaintenance engineerfoundoutthatkeepingasmallspacebetweenAuxcontactorisgoodinthelongrun. Youtoocantryinyourplant. Yes, wewouldliketohaveyourcommentsandsuggestionsonthismodification. www.systemprotection.in +91-265-2225137

  5. CONTACT INFORMATION 301/2/306, SilverlineComplex,OppositeBBC Tower,Sayajigunj,Vadodara - 390005, Gujarat, India. bdm@systemprotection.in www.systemprotection.in +91-265-2225137

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