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How we saved a Process Plant from break-down

We saved a Process Plant from break-down<br><br>

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How we saved a Process Plant from break-down

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  1. ISO 9001:2015 ISO 45001:2015 (OH & S) Certified Company Case Study How we saved a Process Plant from break-down www.systemprotection.in +91-265-2225137

  2. Background : Findings : IntheearlierCaseStudy, wesawhowwe solvedaTransformermal-trippingissue duringourRoutineMaintenanceand Testingactivities. Wearepresenting herewithanothercasewhichdemonstrates whytheseactivitiesshouldbeentrustedto experts, whocanmakesuchroutinejobs moremeaningfulandsaveassets. ItwasthetimetotesttheTIEFeeder. Necessaryshut-downactivitieswerecarried outandpermitsobtained. AteamwascarryingoutRelayTestingand anotherteamwasperformingCTTesting. These6.6kVCTswerehavingaratioof 2500/1A. AswehaveseeninearlierCaseStudythat PrimaryInjectiontestingofCTishaving manylimitations, plusitdoesnotusually providetheDiagnosticsoftheCTs. Moreover, injectionandmeasurementsof suchhighcurrentsalsoposevarious challenges. Wewereappointedtocarryouttheroutine maintenanceandtestingofthe Switchgears, Relays, CTs & PTsinoneofthe CementPlantsinIndia, havingitsown PowerPlant. ThisPowerPlantcombined withGridSupplycateredtotheplantload. Usually, atgeneratingstations, wehaveTIE FeederswhichconnectsGeneratorandGrid tomaintainavailabilityofPowerincaseof variousPower-Flowscenarios. Inmostofthe cases, TIEFeederisaSynchronisingFeeder, whereGeneratorandGridsuppliesare synchronisedtocatertheplantload. It is THE mostimportantFeederofanyPlant, anyprobleminthiscancausetheentire plantblack-out. So, usually, weemployastate-of-the-artCT TestingInstrument, CTAnalyzerofOmicron Make, whichusesIEC61869-2standardand performsmodel-basedtestingwhichisfar moreaccurateandconclusive. DuringthisTesting, ProtectionCore (5P10) ofaCTwashavingaveryhighsecondary resistance, theinstrumentdisplayed “SecondaryWindingresistanceistoohigh”. CTAnalyzerdetermineswindingresistance byapplyingDCcurrentintoSecondary windingandchecksvoltagedropacross SecondaryTerminals. Usually, atgeneratingstations, wehaveTIE FeederswhichconnectsGeneratorandGrid tomaintainavailabilityofPowerincaseof variousPower-Flowscenarios. Inmostofthe cases, TIEFeederisaSynchronisingFeeder, whereGeneratorandGridsuppliesare synchronisedtocatertheplantload. It is THE mostimportantFeederofanyPlant, anyprobleminthiscancausetheentire plantblack-out. ThishighervalueofCTSecondaryWinding indicatesthatCTcouldbeopenandmay mal-operatetherelayincaseofvarious loadingscenarios. Weenquiredaboutany suchincidentinthepast, butthehistory wasclean, therewasnosuchtrippingand plantoperatednormally. Buttherewassomethingabnormalabout thisCTandwedecidedtochecktheCT physically. Andbelowisthephotographof whatwefound. www.systemprotection.in +91-265-2225137

  3. Damaged CT Found in Panel Aswecanseefromtheaboveimages, SecondaryWindingwithitsinternalconnectionis crackedandbarelyhanging, alittlenudgeanditseparated! Wecanalsoobserve hotspots/carbonisationallaround. Root Cause Analysis : Asitcanbeseenfromtheaboveimage, thereisaCTbase-plate, andCTsareusuallymounted inPanelbybase-plates, andusually, upsidedown. MainPrimaryBus-barofCTisconnectedwith mainPowerBus-barofpanel. 1.    UpwardforcebyFixedBase-plate 2.    DownwardforcebyMainPowerBus-bars CTwasinoperationunderstressedconditionforverylongtime. Overaperiod, Secondary Windingstartedgettingdisconnected, andduringtesting, itshowedhigherresistance. www.systemprotection.in +91-265-2225137

  4. Conclusion – how advanced technology can help predict the failure : Therecouldbemanyreasonsforsuch occurrenceandbehaviourofProtection Systemandcanbeaddressedoncase- to-casebasis. Toknowmore, youmay call/writetous. Noteworthyhereis, despitethisdamage, CTmighthavebeentransformingthe currentsfaithfully, astheCTtypewasa mouldedcast resin (arubberyfibrelike material), theleadssomehowremained connected. So, whentherewasprimary current, secondarycurrentcompleted thepathbypuncturingnearby insulation, thisgeneratedhighvoltages andthusthearcingspots - ascanbe seenintheimages. Ifthisremainedundetected, thissurely wouldhaveledtocompletebreak-down innearfuture. Andweallknowwhatit couldhavecostedintermsof productionandrevenue. Allourefforts areviewingtheproblemsfrom customers’ pointandresolvingthemin totality. Andifyouarelookingforadedicated agencythatunderstandsthedirectlink betweenyourassetsandyourrevenue, call/writetous, wewillbehappytoassist you. Aswe’veseenthatthisCTmighthave transformedtheCurrentsfaithfullyor withlittleerror. Therewasnotenough unbalancecurrenttotriptheRelay, so, theFeederdidnottrip, butitwasjuston thevergeoffailurewhenthiswas detected. 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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