commissioning of electrical system.pdf

7/27/2019 Commissioning of Electrical System.pdf

1/104

TECHNCALMANUAL

TM-694

COMMSSIONNGOFELECTRICALSYSTEMS FORCOMMAND CONTROL,

COMMUNCATIONS, COMPUTER,INTELLIGENCE, SURVEILLANCE,ANDRECONNAISSANCE(C41SR)

FACLITIES

APPROVEDFORPUBLICRELEASE DSTRBUTIONI SUNLIMTED

HEADQUARTERS, DEPARTMENTOFTHEARMY23AUGUST2002


2/104

REPRODUCTIONAUTHORZATIONRESTRCTIONS

Thi s manual has been pr epar ed byor f or t he Gover nment and, except t ot he e x t e n t i ndi cat ed bel ow, i s publ i c property andnot subj ect t ocopyr i ght .Repr i nt or r epubl i cat i on of t h i s manual shoul d i ncl ude a c r e di ts ubs t a nt i a l l y as f ol l ows : " Depar t ment of t heArmy, TM- 694,Comm ss i oni ng of El ec t r i c al Syst ems f or Command, Cont r ol ,Communi cat i ons, Comput er , I n t e l l i genc e, Sur vei l l ance, andReconnai ss ance ( C4I SR) F a c i l i t i e s , 23August 2002. "Tabl e 2 - 1 , Recommendedmnimumr esi st ance val ues at 40C al l val uesi n MO) andTabl e 2 - 2 , Recommendedmnimumval ues of pol ar i zat i oni ndexf or al l machi necomponents i nsul at i on cl asses r epr i nt ed wi t hper mssi on f r o mI EEESt d . 43- 2000"I EEERecommendedPr ac t i c eforTest i ng I nsul at i on Resi st ance of Rot at i ng Machi ner y" , copyr i ght000byI EEE TheI EEEdi scl ai m anyr e s po ns i b i l i t y or l i a b i l i t y r e s u l t i ngf r o mt he pl acement and use i n t he descr i bed mat t er .Tabl e 3 - 1 , Medi umvol tagecabl es maxi mumi e l d accept ance testvol t ages (W dc) r epr i nt ed f r o mNETA' s Accept ance Test i ngSpec i f i c at i o ns , copyr i ght 1999 Cour t esy of t he I nt er nat i onalE l e c t r i c al Test i ng Associ at i on Al l r i gh t s r eser ved


3/104

Techni cal ManualNo 5- 694

COMMSSIONINGOFELECTRICALSYSTEMSFORCOMMANDCONTROL, COMMUNICATIONS, COMPUTER, INTELLIGENCE,SURVEILLANCE, ANDRECONNAISSANCE ( C4I SR) FACLITIES

TM- 694

HEADQUARTERSDEPARTMENTOFTHEARMY

Washi ngton, DC, 23August 2002

APPROVEDFORPUBLI CRELEASEDSTRIBUTIONI SUNLIMTED

Paragraph PageCHAPTER1 I NTRODUCTIONPurpose 1- 1 1- 1Scope 1- 2 1- 1Ref erence 1- 3 1- 1General systemt e s t i n g r equi r ement s 1- 4 1- 1Component test i ng 1- 5 1- 2Syst em comm ssi oni ng test i ng 1- 6 1- 2Cost of comm ssi oni ng 1- 7 1- 2

CHAPTER2 GENERALSYSTEMTESTINGREQUREMENTSI nt roducti on 2- 1 2- 1Gener al t e s t pl an 2- 2 2- 1Types of test i ngmet hods 2- 3 2- 8I nsul at i on test i ng 2- 4 2- 8Swi tch/c i rcui t breaker test i ng 2- 5 2- 13Tr ansf ormer test i ng 2- 6 2- 14Rot ati ngmachi net e s t i n g 2- 7 2- 14Protect i ve rel ays 2- 8 2- 16Ground systemt e s t i n g 2- 9 2- 17

CHAPTER3 COMPONENTTESTINGI ntroduct i on t o component t e s t i n g 3- 1 3- 1C r cui t swi t chers 3- 2 3- 1Tr ansf ormer s 3- 3 3- 2Swi t chgear - medi umvol t age 3- 4 3- 3Swi t chgear - l owvol t age 3- 5 3- 3Transfer swi tch 3- 6 3- 4AC/DCdri ves 3- 7 3- 4Mot or s 3- 8 3- 4Generat ors 3- 9 3- 5Batteri es 3- 10 3- 7Battery chargers 3-11 3- 8UPSsyst ems 3- 12 3- 8Cabl es 3- 13 3- 9


4/104

TM- 694

CHAPTER4 MAINPOWERSYSTEM Paragraph

LI STOFTABLES

PageDescri pt i onofmai npower system 4- 1 4-1Operat i on of mai npower system 4- 2 4- 2Comm ss i oni ngpl an f or mai npower system 4- 3 4- 2I n s t a l l a t i o n i nspect i ons and component t e s t i n g of mai npower system 4- 4 4- 2Energi zi ng and t e s t of t hemai npower system 4- 5 4- 3Possi bl e f a i l u r e s andcorrect i ve act i ons of t he mai n power syst em 4- 6 4- 5

CHAPTER STANDBYPOWERSYSTEMDescri pt i on of st andbypower system 5- 1 5- 1Operat i onof st andbypower system 5- 2 5- 1Comm ss i oni ngpl an f or st andbypower system 5-3 5- 2I n s t a l l a t i o n i nspect i ons and component test i ng of st andby power 5- 4 5- 2systemEnergi zi ngandt e s t of t he st andbypower system 5-5 5- 3Possi bl e f a i l u r e s andcorrect i ve act i ons of t he st andby power system 5- 6 5- 4CHAPTER6 UNNTERRUPTIBLEPOWERSUPPLYSYSTEMSDescri pt i on of uni nt errupt i bl e power suppl y (UPS) system 6- 1 6- 1Operat i on of uni nt errupt i bl epower suppl y system 6-2 6- 2Comm ss i oni ngpl an f or t heUPS system 6- 3 6- 2I n s t a l l a t i o n i nspect i ons andcomponent t e s t i n g of t heUPSsystem 6- 4 6- 2Energi zi ng and t e s t of t he UPSsystem 6- 5 6- 3Possi bl e f a i l u r e s andcorrect i ve act i ons 6- 6 6- 6APPENDXA REFERENCES A-1

2- 2 Recommendedmnimumval ues of pol ari zat i on i ndex f o r al l machi ne 2- 16component s i n s u l a t i o n cl asses3- 1 Medi um vol t age cabl esmaxi mum i e l d accept ance t e s t vol t ages ( kV, dc) 3- 104- 1 C rcui t sw t cher f uncti onal checkl i st 4- 34- 2 Possi bl e f a i l u r e s and correcti ve acti ons of t hemai npower system 4- 55- 1 Possi bl e f a i l u r e s andcorrecti ve acti ons of t he st andby power system 5- 46- 1 Possi bl e f a i l u r e s andcorrecti ve act i ons of t heUPSsystem 6- 6

Tabl e T i t l e Page1- 1 Cost s of comm ssi oni ng, newconst ructi on 1- 32- 1 Recommendedmni mumnsul at i on r e s i s t a n c e val ues at 40C( a l l val ues i n 2- 10M


5/104

LISTOFFIGURES

TM- 694

Fi gur e T i t l e PageFi gur e 2- 1 Sampl e of acommssi oni ng pl an 2- 8Fi gure 2- 2 Step- vol t age vs . t i me 2-12Fi gure 2-3 Step- vol t age hi gh-pot ent i al t e s t current 2-12Fi gure' 2-4 Power t r ansf ormer di agr am ( Repri nt ed f romDepar t ment of t heArmyTM- 2-15686 Power Transf ormer Mai nt enance and Accept ance Test i ng 16November1998)Fi gure 3-1 S t a t i c UPSsyst em150 t o 750kVA court esy of Li ebert ) . 3- 9Fi gur e 4-1 Mai npower syst emsi ngl e l i n e di agr am 4-7Fi gure 4- 2 Mai npower syst emcont rol cabl e bl ock di agr am 4-8Fi gure 4-3 Mai npower syst emf unct i onal di agr am- c i r c u i t swi t cher ( t y p i c a l f or 2) 4-9Fi gure 4-4 Mai npower syst emf unct i onal di agr am- sw t chgear l oad breaker ( t y p i c a l f or 8) 4- 10Fi gure 4-5 Mai npower syst emf unct i onal di agr am- sw t chgear i ncomng breaker ( t y pi c al 4- 11f or 3)Fi gur e 4- 6 Mai npower syst emc i r c u i t sw t cher wi ri ng di agr am( t y pi c al f o r 2) 4- 12Fi gur e 4- 7 Mai npower syst emi ncomng breaker w r i ng di agr am 4- 13Fi gur e 4- 8 Sampl e of compl et edDAForm7463-R 4- 14Fi gure 4-9 Sampl e of compl et edDAForm7464-R 4- 15Fi gure 4- 10 Sampl e of compl et edDAForm7465-R 4- 16Fi gure 4- 11 Sampl e of compl et edDAForm7466-R 4- 17Fi gur e 4- 12 Sampl e of compl et edDAForm7467-R 4- 18Fi gure 5-1 St andbypower syst emsi ngl e l i n e di agr am 5-6Fi gur e 5- 2 St andbypower syst embl ock di agr am 5-7Fi gure 5-3 St andby power syst emwi ri ng di agr am 5-8Fi gure 5-4 Engi ne f a u l t t r e e 5-9Fi gure 5-5 Sampl e of compl et edDAForm7468-R 5- 10Fi gur e 5- 6 Sampl e of compl et edDAForm7469-R 5- 12Fi gure 5-7 Sampl e of compl et edDAForm7470-R 5- 13Fi gure 6-1 Uni nt err upt i bl epower suppl y syst emsi ngl e l i n e di agr am 6-9Fi gure 6- 2 Uni nt err upt i bl epower suppl y syst embl ock di agr am 6- 10Fi gure 6-3 Uni nt err upt i bl epower suppl y syst emw r i ng di agr am 6- 11Fi gure 6-4 Sampl e of compl et edDAForm7471-R 6- 12Fi gur e 6- 5 Sampl e of compl et edDAForm7472-R 6- 13Fi gur e 6- 6 Sampl e of compl et edDAForm7473- R 6- 14Fi gur e 6- 7 Sampl e of compl et edDAForm7474- R 6- 15Fi gur e 6- 8 Sampl e of compl et edDAForm7475-R 6- 16


6/104

1- 1 . Purpose

1- 2 Scope

1- 3 Ref er ences

CHAPTERINTRODUCTION

TM- 694

Thepur pose of t h i s publ i cat i on i s t o pr ovi de gui dance t o engi neer i ng manager s/ pl anner s f or t hecomm ssi oni ng of e l e c t r i c a l sys t ems at command, c o n t r o l , communi cat i ons, comput er, i nt e l l i ge nc e,survei l l ance, and r econnai ssance ( C4I SR) f a c i l i t i e s . I t s p e c i f i c a l l y addresses di f f erent t ypes of e l e c t r i c a lpower syst ems, t he pr eparat i on of comm ssi oni ng st at ement s ofwork (SOW, s pe ci f i c a t i o ns , andexampl es of comm ssi oni ng t e s t s t h a t shoul d be i ncl uded dur i ng s t a r t - u p . E l e c t r i c a l sys t emscomm ssi oni ng ( somet i mes referred t o as "accept ance t esti ng") onnewp r o j e c t s i s c r i t i c a l to ascert ai n t h a ta syst emi s i n s t a l l e d corr ectl y andt h a t i t wi l l r emai n i n servi ce f or i t s pr oj ect ed l i f e cycl e

Gui dancef or comm ssi oni ngof e l e c t r i c power syst ems onnewproj ect s i s di scussed i n t h i s manual . Thesys t ems addr essed i ncl ude t hemai npower substat i on, st andby generat or, anduni nt err upt i bl e power

. suppl y . The f ol l ow ng ar eas ar e addressed : gener al comm ssi oni ng c r i t e r i a , comm ssi oni ng p l a n,document at i on r equi r ement s, v e r i f i c a t i o n procedur es, syst emf unct i onal per f or mance t e s t s , def er r edper f or mance t e s t s , corr ecti ve measures, accept ance document at i on, post comm ssi oni ng f ol l owupprocedures andexampl es of comm ssi oni ng

Appendi xAcont ai ns a l i s t of r ef erences used i n t h i s manual . Ot her per t i nent l i t e r a t u r e maybe subst i t ut edor usedas suppl ement s . Prescri bed f or ms ar e al so l i s t e d i n appendi xA1- 4 Gener al syst emt est i ng r equi r ement sThepur pose of e l e c t r i c syst ems comm ssi oni ng i s to i ncrease t he r e l i a b i l i t y of e l e c t r i c a l power syst emsa f t e r i n s t a l l a t i o n by i dent i f yi ng probl ems andpr ovi di ng a s e t of basel i ne val ues f or compar i son wi t hsubsequent rout i ne t e s t s . Aprocedure shoul d be devel oped t o i ncl ude apl anned appr oach (road map) ofwhat shoul d be done i n order t o veri f y t heproper syst emi n s t a l l a t i o n . Thi s procedur e i s t hecomm ssi oni ng pl an. Speci f i c areas addr essed i n acomm ssi oni ng pl an i ncl ude t he v e r i f i c a t i o n of t hei n s t a l l a t i o n of al l equi pment / component s, i n t e r f a c e connect i ons bet ween equi pment and i ndi vi dualsys t ems, and i nt er connect i on drawi ngs . Thedevel opment of t h i s t e s t pl an s p e c i f i c t o each syst emand/ orcomponent i s keyt o t he usef ul ness of anymai nt enance program Thepl an consi st s of t he schedul e ofwhenaccept ance and rout i ne t e s t s shoul d be perf ormed, t e s t f or ms t obe used t o recordthe outcome of t het e s t s whi char e r e t a i ne d f or compar i son w t h previ ous and subsequent t e s t s , and a l i s t i n g of t her equi redt e s t devi ces . Si nce t he r e s u l t s of t he comm ssi oni ng t e s t s becom basel i ne t e s t val ues t ocomparewi t hl a t e r t e s t s and t he r e s u l t s of t he rout i ne mai nt enance t e s t s ar e compi l ed t o i d e n t i f y anydownward t rend i nper f ormance, i t i s v i t a l t o t he mai nt enance programt o have accur at e and compl et e records . To per f or mt he t e s t i n g , t he pl an l i s t s al l r equi red t e s t s i n order of per f or mance andgi ves a schedul e f or each t e s t . Thework i t ems and schedul e dependonmany i t ems i ncl udi ng t he i mport ance and cost of t he equi pment ,consequences of f a i l u r e , ageof equi pment , past and future f r equency of s e r v i c e , hour s of operat i on, f ut uremai nt enance a v a i l a b i l i t y , envi r onment al condi t i ons, and safety r equi r ement s .


7/104

TM- 694

1- 5 Component t e st i ngTher e l i a b i l i t y of any systemi s dependent on t he i nt erconnect i on of t he equi pment and t he equi pmenti t s e l f . Thi s manual ' s purpose i s pr edom nat el y f or t e s t i n g of e l e c t r i c syst ems t hemsel ves . I t i s assumedt h a t t he detai l edandcompr ehensi ve i ndi vi dual t est i ng of equi pment has been compl et ed bef ore t hecommenci ng of comm ssi oni ng of t he system However , general t e st i ng pr ocedur es f or t he component sof t he syst ems descr i bed i n t h i s manual are addr ess ed i n chapt er 3 . Comm ss i oni ng r equi r ement s f or t hesystemcomponent s are t y p i c a l l y provi ded w t h t he or i g i na l pr oposal f or t heprocur ement of t heequi pment . Ther equi r ement s pr ovi ded by t he equi pment manuf act urer shoul d be adher ed t o i n addi t i ont o t he recommended t est i ng herei n . Al t hough there aremany of d i f f e r e n t component s t o any e l e c t r i c a lsystem there are somet e s t s t h a t are commonamong t he equi pment . Exampl es of t he common t est i ngpr ocedur es i ncl ude t he ass embl y check, al i gnment check, gr oundi ng v e r i f i c a t i o n , i nsul at i on r esi st ancet e s t s and pol ar i zat i on i ndex t o nameafew Thesecommon t e s t s are descri bed i n de t a i l i n chapt er 2S u f f i c i e n t t i me shoul dbe al l ocat ed t o defi ne t he i nspecti ons r equi r ed, per formt he check, anddocumentt he r e s u l t s . Ar evi ewof t he systemdr aw ngs wi l l showmaj or pi eces of equi pment . Spec i f i c pr ocedur esshoul d be devel oped f or each t e s t r ef erenci ng t he equi pment t o be used, dr aw ngs t o be f ol l owed, andstepby s t e p pr ocedur es w t h r eadi ngs t o be r ecor ded and f orms f or t he r e s u l t s .1- 6 Systemcomm ss i oni ng t e st i ngE l e c t r i c a l syst ems comm ss i oni ng on newpr oj ect s i s c r i t i c a l t o ascer t ai n t h a t a systemi s i n s t a l l e dpr operl y and t h a t i t wi l l r emai n i n serv i ce f or i t s pr oj ect ed l i f e cycl e Thecomm ssi oni ng of a systemenc ompasses t he i ndi vi dual t e s t i n g of the re l ated component s , t he v e r i f i c a t i o n of t he componenti nt er connect i on agai nst t he dr aw ngs, and t he f uncti onal t e s t i n g of t he systemas awhol e Anunder st andi ng of t he equi pment i nvol ved and t hemodes of operat i on f or asystemare e s s e nt i a l t o t hedevel opment of t he systemcomm ss i oni ng pl an . Asurvey of t he equi pment of t he systemand l i s t i n g t heequi pment i n order of i mpor t ance andstartup i s t he f i r s t s t e p i n devel opi ng t he comm ss i oni ng pl an . Theschedul e of t he t e s t s and i nspecti ons i s dependent onmanyaspect s of t he equi pment such as i t si mpor t ance and c o s t , t he f r equency of s e r v i c e , hour s of operat i on, envi r onment al condi t i ons, a c c e s s i b i l i t y ,and s a f e t y r equi r ement s . Thei nspect i on, t e s t i n g , and st ar t up pl an i s then devel oped i n conj unc t i on w t ht h i s s chedul e w t h i ns t r u ct i ons and pr ocedur es f or t he t e s t pl an . Exampl es of syst ems test i ng aredi scussed i n chapt er s 4, 5and6 DAForm7463-Rt hrough7475-Rare c h e c k l i s t s desi gned t o a s s i s t i nthese i nspecti ons and t e s t s . They are f ound as r epr oduci bl e f orms a t t he end of t h i s manual . Pr obl emsmaya r i s e dur i ng t he t est i ngof t he equi pment andsyst ems . I n order t o i d e n t i f y andcorrect thesepr obl ems, t r oubl eshoot i ng t echni ques shoul d bedevel oped . Checki ng of equi pment such as f uses, l i g h t s ,andbreakers f or c ont i nui t y , equi pment cal i brat i on and s e t t i n g s , and i nves t i gat i ng for f aul ty equi pment orconnecti ons shoul d be t he f i r s t t r oubl eshoot i ng st eps . For al l pr obl ems, t he equi pment andcomponentmanual s are consul t ed f or t r oubl eshoot i ng di r ecti ons . Exampl esof t he possi bl e causes t o commonprobl ems are shownf or each syst em i n t he chapt er s t h a t f ol l ow1- 7 Cost of comm ssi oni ngThec o s t of comm ssi oni ng f or an e l e c t r i c a l system i s dependent uponmany f a c t o r s i ncl udi ng t he systems i z e , compl exi t y and t he l e ve l of r e l i a b i l i t y desi r ed. Newbui l di ng const r uct i on, r enovat i on of an exi s t i ngb ui l d i ng, or t hemoder ni zat i on al so wi l l e f f e c t t he c o s t of comm ssi oni ng . Exper i ence has shownt h a t t hei n i t i a l comm ss i oni ng c o s t i s moret han o f f s e t by i ncreased systemr e l i a b i l i t y and r educed operat i ng c o s t sThec o s t f or comm ss i oni nganewbui l di ng can r ange f r om0 5 t o 1 . 5 per cent of t he t o t a l const r uct i on c o sas shown i n t he t abl ebel ow For an exi s t i ng bui l di ng t he comm ss i oni ng costs can r ange from hree tof i v e per cent of t he t o t a l operat i ng c o s t s .


8/104

Tabl e 1- 1 Cost s of comm ssi oni ng, newconst r ucti on

Commssi oni ngScope CostEnt i re bui l di ng( HVAC, Cont r ol s, E l e c t r i c a l , 0 5- 1 . 5%of t o t a l constr ucti on c o s tMechani cal ) Comm ssi oni ng .HVACand AutomatedCont r ol Syst emCommssi oni ng 1 . 5 - 2 . 5%of mechani cal systemc o s tEl ectr i cal Syst ems Comm ssi oni ng 1 . 0 - 1 . 5%of e l ec t r i c al system c o s tEner gy Ef f i c i encyMeasur es Comm ssi oni ng $0.23-0. 28 per squar e f oot

TM- 694

Sour ce : Por t l andEner gy Conservat i on I ncor porat ed/ Bui l di ng Comm ssi oni ng Gui de, USDepar t ment ofEner gy, 30 J u l y 1998


9/104

2- 1 . I nt roducti on

2- 2 . Gener al t e s t pl an

CHAPTER2GENERALSYSTEMTESTINGREQUREMENTS

The pur pose of el ec t r i c al testi ng on syst ems and t h ei r component s i s t wo- f ol d . The f i r s t i s t o check t hei n s t a l l a t i o n of t he equi pment andperformcomponent and syst ems t e s t s t o ensure t h a t , whenener gi zed,t he systemwi l l f uncti on pr oper l y . Thesecond i s t o devel op a s et of basel i ne t e s t r e s ul t s f or compar i son i nfuture t e s t i n g t o i d e n t i f y equi pment det e r i o r a t i o n . Comm ssi oni ng t e s t s ar e usual l y per f or med byi ndependent c o n t r a c t o r s , t he i n s t a l l a t i o n c o n t r a c t o r , or t hemanuf act ur er . Each comm ssi oni ng t e s t shoul dbe wi t nessed byaperson not associ at ed prof essi onal l y w t h t he per son per f or m ng t he t e s t . Thei ndi vi dual s whoper f or mt he accept ance t e s t s shoul d be c e r t i f i e d and/ or l i censed f o r t he equi pment undert e s t . Thesystem shoul d be i n i t i a l l y checked f o r damage, det e r i o r a t i o n, andcomponent f a i l u r e s usi ngspeci f i c component checks, i nspect i ons, and t e s t s def i ned by t he equi pment manuf act ur er . Thent hei nt er connect i on of t hesystemcomponent s shoul d be checked, usi ng deener gi zed andener gi zed methods,t o veri f y t heproper i nt er connect i on and oper at i on of t he components, i ncl udi ng on/ of f c o n t r o l , systemprocess i n t e r l o c k s , and protect i ve rel ayi ng f uncti ons . Once t heabove t e s t s are compl ete, t he systemcanbe ener gi zed andoper at i onal t e s t s and measur ement s shoul d be per f or med . Al l st eps and r e s ul t s of t hetesti ng shoul d be c a r e f u l l y document ed f or r evi ew and f or use i n t he future f or compar i son wi th t her e s ul t s of future t e s t s . Manyof t hesame component t es t s i n i t i a l l y r un wi l l be per f or med a t regul ari n t e r v a l s as p a r t of a mai nt enanceprogr am Thenew e su l t s wi l l be compar ed t o t he i n i t i a l r e s ul t s , wherevar i at i ons maybe i n d i c a t i v e of probl ems l i k e d e t e r i o r a t i o n of i n s u l a t i o n or d i r t y equi pment . The st epsi nvol ved areto r evi ewt he system and equi pment, devel op agener al system and speci f i c equi pment t e s tpl an, pr ovi de i nspecti on and checks, performcomponent t e s t i n g, veri f y andcheck t he cont i nui ty ofw r i ng, check control f uncti ons, c a l i b r a t e i nstr uments and r e l a y s , ener gi ze por t i ons of t he c i r c u i t s andcheckf or proper oper at i on i n a s pec i f i c o r de r , and, once compl ete, performs p e c i f i c checks and controlt e s t s on t hecompl et e syst emdur i ng i n i t i a l per i od of oper at i on.

There ar e manag ement , econom c, and t e c h ni c a l r equi r ement s associ at ed w t h every t e s t pl an . Thedevel opment anduse of acompr ehensi ve t e s t pl an i s l i k e an i nsur ance pol i cy . Whi l e i t has s p e c i f i c c o s t s ,i t does not usual l y showany di r e c t paybacks as t hesyst ems wi l l usual l y startup wi t hout si gni f i cantpr obl ems such a s equi pment f a i l u r e or l o s t t i me . The c o s t of t he t e s t s wi l l r i s e wi t h t he compl exi t y of t het e s t program Many i nspect i ons andt e s t s ar e r edundant, but ar e used a s checks and bal ances bef oresystemenergi zat i on t o ensur e successf ul s t a r t u p andoper at i on. Manyt i mes, i f t heequi pment i s i n t hesam oper at i ng condi t i on as when i t l e f t t he factory and t hesystemdesi gn and i n s t a l l a t i o n ar e adequate,t he systemstartup and t es t i n g wi l l f i nd no probl ems and t he deener gi zed checks andener gi zed t e s t i n gmayseem l i k e awast e of t i me andmoney There ar eoccasi ons whenat e s t wi l l showbad i nsul ati on l i k eaf aul t ed t r ansf ormer wi ndi ng or am ssi ng i n t e r l o c k i n acontrol scheme t h a t woul d have r esul t ed i ncat ast r ophi c f a i l u r e i f t hesys t emhad been ener gi zed. The compl exi t y of t he systemandequi pment ,exper i ence of t hede si g ner s / i n st a l l er s / o pe r a t o r s , t he possi bl e r e s ul t s of a f a i l u r e , and t hecosts of t het e s t i n g ar e al l consi der edwhendet er m ni ng t heamount of t e s t i n g r equi r ed . The component andsystemi nspect i ons and checks are t he keyt o t he success of t heprogram Suf f i ci ent t i me shoul d be al l ocat ed t odef i ne t he i nspecti ons r equi r ed, per f or mt he check, and doc ument t he r e s u l t s . Aevi ewof t he systemdrawi ngs wi l l showmaj or pi eces of equi pment . Speci f i c procedur es shoul d be devel oped f o r eachcomm ssi oni ng t e s t ref er enci ng t heequi pment t o be used, syst ems oper at i on document s ( SODs) , syst ems

TM-694


10/104

TM5- 694

operati onandmai nt enance manual s (SOMMs), dr aw ngs t o be f ol l owed, and s t e p by s t e p pr ocedur es w t hr eadi ngs t o be recorded and f or ms f o r the r e s u l t s . Once t he equi pment i s i dent i f i ed, t he manuf act ur er ' smanual s shoul d be used t o i d e n t i f y t he r equi r ed r ecei pt i n spe ct i o ns , handl i ng and i n s t a l l a t i o n pr ocedur es,energi zed andde- energi zed component t e s t s , dr aw ng andw r i n g ver i f i c at i o n , mnimume p o r tr equi r ements f or on- goi ng mai nt enance and t e s t i ng ba s el i n e, and r equi r ements f or r epai r and r e t es t i ng i fc er t a i n checks and t e s t s pr oduce unsat i sf act ory r e s u l t s . Top er fo rmt he t e s t i ng, ad e f i n i t e pl an l i s t i n g al lr equi r ed t e s t s i n or der of per f ormance and gi vi ng aschedul e f o r each t e s t shoul d be devel oped . Theworki t ems and schedul e wi l l depend onmany i t ems i ncl udi ng t he i mport ance andcost of t he equi pment ,consequences of f a i l ur e, age of equi pment , past and future f r equency of s er v i c e, hour s of operati on, futuremai nt enance a v a i l a b i l i t y , envi r onment al condi t i ons, andsafety r equi r ements . (For r emot e unat t endedsyst ems, addi t i onal i t ems wi l l be r equi r ed i n t he i n i t i a l t e s t p l a n, to hel p assure al l possi bl e operati ngsequences, mal f unct i ons, and cor r ecti ons have been v e r i f i e d . Thepl an shoul d be revi sed as the i nspecti onand t e s t i ng pr oceeds dependi ngon t he accept abi l i ty of t he r e s u l t s . ) Cert ai n f a i l ur e smay r equi r e r e t es t i ngof component andsystemoperati on Whenw r i n g pr obl ems ar e f ound and r e p ai r e d , a l l a f f e c t e d w r i n gt er mnat i ons shoul d be r e - v er i f i ed f or t h ei r pr oper connect i ons . Thesuccess of at e s t programand i t s uset o suppor t an on- goi ng mai ntenance programa l s o gr eatl y depends ont he a t t e nt i o n gi ven t o devel opmentand revi ew of t he t e s t records andreportsby t he testi ng and oper ati ons personnel andsystemmanagement . Tohave an e f f ec t i v e program i t i s i mper at i ve t h a t t e s t dat a be compl et e, organi zed, andreadi l y avai l abl e . Form shoul d be devel oped w t h t he t e s t pr ocedur es whi ch l i s t t he r equi r ed t e s tpr ocedur e, t e s t sequence, t e s t i nst r ument , t e s t dat a and, most i mpor t ant l y, acceptabl e t e s t val ues f or eachr e s ul t . ( Exampl es of t e s t f or ms ar e f ound i n each appl i cabl e chapt er . These f or ms shoul d onl y be used assampl es . ) Ar emar ks area shoul d be i ncl uded t o l i s t any pass or f a i l , comment s, r ecommendat i ons f orr epai r andr e t e s t , addi t i onal f ol l ow- up t e s t i ng r equi r ed dur i ng t he next steps of t he systemo pe r a t i o n, andhel pf ul i nf ormati on f or future t e s t i n g . Not e t h a t the data c o l l e c t e d and recorded wi l l be used over t heyears t o anal yze trends f or equi pment det eri orati on or hel p determne causes f or systemmal f unct i ons, soi f t he records ar e not compl et e and correct a l a r ge part of t he usef ul ness of agoodt e s t programi s l o s t .Thet echni cal r equi r ement s f o r at e s t programcan be stated as f ol l ows .a Sur vey ofsystemequi pment . Anaccur at e andcompl et e descr i pt i on of apower systemand i t sequi pment i s r equi r ed t o devel op at e s t program Thi s wi l l i ncl ude wri t t en systemdes c r i pt i o n, one- l i nedi agrams, short c i r c u i t andcoor di nati on s t u di e s, three l i n e di agrams, control l o g i c di agr ams, schemat i cl ogi c di agrams, cabl e bl ock and i nt erconnect i ng di agrams, equi pment physi cal andw r i n g dr aw ngs,equi pment manual s, and a u x i l i a r y systemmanual s and dr aw ngs f or suppor t syst ems such as l i g h t i n g , f i r

pr otect i on, backup power , bui l di ng and bui l di ng s e r v i c es , et c . . These document s serve t o depi ct t hedesi gn and operati onof t he systemf or use dur i ng i ns t al l a t i on, t e s t i ng, s t ar t u p, operat i on, andmai nt enance . Var i ous st andar ds groups such as t he I n s t i t u t e of El ec t r i c al andEl ectr oni cs Engi neer s( I EEE) and Nat i onal El ec t r i c al Manuf act ur er s Associ ati on (NEMA) have devel oped st andar ds f or t hesemater i al s . Typi cal dr aw ngs and t h ei r def i n i t i ons ar e as f ol l ows :( 1 ) One- l i ne ( s i n g l e - l i n e ) di agr am Shows, bymeans of s i ngl e l i n e s andgr aphi c symbol s, t he f l oof el ec t r i c al power or t he cour se of el ec t r i c al c i r c u i t symbol s, and howt hey ar e connect ed . I n t h i s

di agr am physi cal rel ati onshi ps ar e usual l y di sr egarded.( 2 ) Bl ock di agr am Shows agroup of i nter connect ed bl ocks, each of whi ch represent adevi ce orsubsyst em( 3) Schemat i c ( el ement ar y) di agr am Shows al l c i r c u i t s and devi ce el ement s of t he equi pment .Thi s di agr amemphasi zes t he devi ce el ement s and t h ei r f un ct i o ns , and i t i s al ways drawnw t h al l devi ceshown i n deener gi zedmode


11/104

( 4) Cont r ol sequence ( t r u t h - t a b l e ) di agr am Shows adescri pti on of t he contact po si t i o ns ,connect i ons, t h a t ar emade f or each posi ti on of control acti on or devi ce .

( 6) I nt er connect i on di agr am Shows onl y t he e x t e r n a l connect i on bet ween cont rol l ers andassoci at ed equi pment or bet ween var i ous housi ng u n i t s of anassembl y of sw t chgear apparat us .

TM- 694

( S) W r i n g di agr am( connect i on di agr am . Locat es and i d e n t i f i e s e l e c t r i c a l devi ces, t erm nal s, andi nt er connecti ng wres i n an assembl y . Thi s di agr ammayshowi nt er connecti ng w r i n gby l i n e s ortermnal desi gnat i ons .

( 7 ) Ci rcui t l ayout androut i ngdi agr am Shows t he physi cal l ayout of t he f a c i l i t y and equi pmentandhowt he c i r c u i t t o t he var i ous equi pment i s r un.( 8 ) Short - ci rcui t coordi nat i on st udy. E l e c t r i c a l power systemd a t a , di agrams, and dr aw ngs ar eneeded dur i ng mai nt enance and t e s t i n g of e l e c t r i c a l equi pment . Thi s may i nvol ve i nf ormat i onanddatar e l a t i n g t o protecti ve devi ces and r el ays. Such data a r e usual l y f ound i n a s h o r t - c i r c u i t coordi nat i on st udyandusual l y encompass al l t he s h o r t - c i r c u i t val ues a va i l a bl e i n t hepower system r e l a ys , and t r i p devi ces e t t i n g s . Nor mal l y, t h i s st udy i s per f or med dur i ng t heconst r ucti on phase of t he f a c i l i t y . I t woul d bemuchmore d e s i r a b l e t o perform hi s engi neeri ngst udy as p a r t of t he i n i t i a l f a c i l i t y desi gn, and t hen

val i dat e i t dur i ngt he constr ucti on phase t o assure t h a t equi pment and val ues speci f i ed have been met .Wenaccept i ng t he f a c i l i t y , t h i s st udy data shoul d be used as abenchmar k, andany changes t h a t mayhave beenmadedur i ng const r ucti on i n t he syst emshoul d be i ncor por at ed t o updat e t he st udy f or futurer eferences .b List ingof c r i t i c a l systemequi pment . Themaj or equi pment of asystem i s v i t a l t o i t s oper at i onandf a i l u r e of t h i s equi pment coul dbe at h r e a t t o per sonnel and systemoper at i on, i . e . , p ot e nt i a l si ngl e poi ntf a i l u r e s . Froma r evi ewof t he syst emdocumentat i on, especi al l y thesi ngl e l i n e di agr am a l i s t of c r i t i c a lequi pment and t he or der i n whi ch t he i t e m shoul d be i n s pe c t e d , t e s t e d , andenergi zed shoul d bedevel oped. From hi s l i s t , thepl an andschedul e f o r t he t e s t pr ogr amcanbe devel oped . Nor mal l y t hel i s t i n g i n or der of c r i t i c a l i t y of t he equi pment i s f r o mt he nor mal power sour ce i n t o t he systemw t h onsi t esources f a i l i n g a f t e r t hemai npower source and d i s t r i b u t i o n equi pment . The l i s t i n gmaybe d i f f i c u l t t o

prepare as i t w i l l vary f or each system and thereforeat eamf r omsystemengi neeri ng, oper at i ons, andmai nt enance maybe r equi r ed . Thi s wi l l a l s o serve t o provi de t he oper at i ons andmai nt enance personnelan oppor t uni t y t o r evi ew t he systemdur i ng the earl y st ages of ap r oj e ct , whi chhel ps them n t heper f or mance of t h e i r workc Stepsf or t he t e s t programAes t programw i l l commencea f t e r compl et i on of i n s t a l l a t i o n and wi l l

usual l y i ncl ude f i e l d i nspecti on and i n s t a l l a t i o n checks, deener gi zed component t e s t i n g , veri fyi nst r ument and r el ay oper at i on and c al i br a t i on, v i s ua l check of al l w ri ng, conti nui ty checki ng of controlc i r c u i t s , ener gi zed f unct i onal t e s t i n g of control c i r c u i t s , megger t e s t i n g of power c i r c u i t s , t e s t of powerc i r c u i t s phasi ng, ener gi zi ng of equi pment , and ser vi ce t e s t i n g . I f pr obl ems are f ound dur i ng t he t esti ngan anal ysi s shoul d beper f or med, and a r epai r and r e t e s t shoul d be per f or med t h a t i s appr ovedby t hecomm ssi oni ng a ut h o r i t y , manuf acturer , engi neer, and systemoper at or . Many of these i n i t i a l t e s t s wi l l ber epeat ed p e r i o d i c a l l y as part of t he systemmai nt enance pr ogr amdependi ngon t he l oad condi t i ons, dut yc y c l e , envi r onmental condi t i ons, andt he c r i t i c a l nature of t he equi pment . Because of t h i s , t hecompl et eness andc l a r i t y of t he t e s t reports i s i mpor t ant as they suppl y basel i ne datafor compar i son w t ht he r e s u l t s of t he mai nt enance t e s t s .d Gener al d e f i n i t i o n of t e s t steps Pr i or t o t e s t i n g , o ve r a l l compl et i on of i n s t a l l a t i o n shoul d bev e r i f i e d i ncl udi ng s e t t i n g , w ri ng, gr oundi ngof t he equi pment , and condi t i oni ng of t he overal l a r e a , i . e . ,cl ean compl et e s i t e t o work i n . Thi s i s consi dered apretest . Not e : al l of t he i t em bel owshoul d be

2- 3


12/104

TM5- 694

per f or med i n s t r i c t accor dance w t h t he dr aw ngs, syst ems oper at i ons document s, syst ems oper ati on andmai nt enance manual s ( pr ovi ded by c o n t r a c t o r ) , and t he engi neer' s andmanuf act ur er' s i n s t r u c t i o n s f oreach pi ece of equi pment . Themanuf act urer t y p i c a l l y pr ovi des t he i n s t r u c t i o n s i n t he formof di agr amsi ndi cat i nghow o connect t he t e s t i nst r ument s as wel l as charts i ndi cat i ng accept abl e andunaccept abl eval ues . Theengi neer ' s i n s t r u c t i o n s w l l be f ound i n t he systems p e c i f i c a t i o n s and draw ngs, and t hemanuf act ur er ' s i n s t r u c t i o n s are f ound i n t he equi pment manual s and dr awi ngs . I EEE, NEMA Nat i onalFi re Protect i on Associ at i on (NFPA), andother st andards al so i ncl ude accept abl e procedures for theper f ormance of t he t e s t s . As t he accept ance t e s t s andenergi zati on i s per f or med ; f a i l u r e s and r e p a i r s ,a v a i l a b i l i t y of equi pment and per sonnel , schedul es, weat her , and other i tem maycause t he del ay or non-per f or mance of at e s t . I n any of these cases, the mssi ng, f a i l e d , newl y r equi r ed, or post poned t e s t shoul dbe not ed i n t he t e s t document at i on al ong w t h t hereason f o r m s s i ng t he t e s t andt he t echni calconsequences . Aneval uati on shoul d be made as t o whet her t he systemcanbe ener gi zed w t hout t h i s t e s tnot i ng t he possi bl e effect on s a f e t y , per sonnel , and equi pment operat i on; andnot i ngwhenor even i f t het e s t shoul d be per f or med i n t he future I f t he t e s t yet t o be perf ormed or needs t o be per f or med t o provet he adequacy of a r e pai r , t he t e s t shoul d be schedul ed w t h t he systemoper at i ons per sonnel as p a r t of anon- goi ng mai nt enance pr ogr am

( 1) F i e l d i nspecti on and i n s t a l l a t i o n checks . I ncl ude i nspecti on of i mpact recorders, v e r i f i c a t i o n ofr emoval of shi ppi ng braces, i nspecti on of i n s t a l l a t i o n agai nst dr awi ngs andnamepl at es, i nspecti ng ofcomponent s f or damageand c l e a n l i n e s s , i nspecti on of i n s u l a t o r s f or cracki ng, i nspecti on of anchorageandgroundi ng, s i z ing check of f uses andbreakers, al i gnment and adj ust ment checks, mechani caloper ati on and i nt erl ock checks, l ubri cat i on appl i c a t i on , v e r i f i c a t i o n of i nsul at i ng l i q u i d or gas l e v e l orpressure, and v e r i f i c a t i o n t h at l oc al safety equi pment i s i n pl ace

( 2) De- ener gi zed component testi ng I ncl ude pressure and l e ve l checks, megger and i nsul at i onresi st ance testi ng of equi pment andconnect i ons i ncl udi ng grounds, turns r a t i o meas ur ement s , pol ari tyt e s t s , i nsul ati ng l i q u i d d i e l e c t r i c andmoi st ure t e s t i n g , power factor or di ssi pat i on factor t e s t s ,over pot ent i al t e s t s , cont act r e s i s t a n c e measur ement s, oper ati on t i me t r ave l anal ys i s , batteryand c e l lvol t age meas ur ement s, charger / UPS ( uni nt err upt i bl e power suppl y)/ gener ator current and vol t agemeas ur ement s , andequi pment / syst ems i mpedance or resi st ance t e s t s .

( 3) Ve r i f i c a t i o n of i nst r ument andrel ay operat i on andcal i brati on . I ncl ude v e r i f i c a t i o n ofauxi l i ary devi ce oper at i on, c a l i b r a t i o n of i nst r uments and r e l a y s , f unct i onal t e s t i n g of i ndi vi duali nst rument s/ gauges/ al arm / rel ays/ l i mt sw tches/ et c .

( 4) Vi sual check of a l l w r i ng. I ncl ude v i s u al i nspecti on of al l w r i ng agai nst t he schemat i c andw r i ng, both i n t e r n a l and e xt e r n al , di agr ams .( S) Cont i nui t y checki ngof cont r ol c i r c u i t s . I ncl ude cont i nui t y andvol t age testi ng of al l cont rol

c i r c u i t s agai nst schemat i c di agr ams .( 6 ) Ener gi zedf unct i onal testi ng of cont r ol c i r c u i t s . I ncl ude ener gi zi ng of control c i r c u i t s andchecki ng al l r emot e and l o ca l c l o s e / t r i p oper ati ons, protect i ve r e l a y oper ati ons, s a f e t y and i n t e r l o c koperati ons, and al l process and communi cat i on oper at i ons .( 7 ) Megger testi ngofpower c i r c u i t s . I ncl udemegger t e s t i n g of power , current t r ansf ormer, and

pot e nt i a l t r ansf ormer buses and cabl es a f t e r connect i on .( 8) Phaseout test i ng ofpower c i r c u i t s . I ncl ude pr i mar y and/ or secondar y i n j e c t i on t e s t i n g f or

c i r c u i t i mpedance andp o l a r i t y checks .

2- 4


13/104

( 9) Ener gi zi ngofequi pment . I ncl ude energi zi ng of equi pment i n s p e c i f i c order a f t e r al l abovetest i ng i s compl et e andeval uat ed .( 10) Servi ce testi ng I ncl udemeas ur ement of val ue and r e l a t i o n s h i p of power, pot e nt i a l , andcurrent on sources, buses, f eeders, and n eu t r a l s i n t hepower system( 11) Post accept ance tests . I ncl ude on- goi ngmai ntenance and operat i on t e s t s , correcti ve acti on

t e s t s , and def erred t e s t i n g.e Report s , f orms , andrecords Accurateandcompl ete r e p o r t s , form, and records shoul d bedevel oped and kept updat ed a f t e r t he t e s t i n g f or t he equi pment and t he systemf or i n i t i a l eval uat i on of t her e s u l t s bef ore energi zat i onandon- goi ng eval uat i onby operat i ons and mai ntenance . Anal ysi s of t he dataand r e sul t s shoul d provi de adeci si on t o s t a r t u p and agui de f or futuremai ntenance requi rement s and i t scost . Fi gures shoul d be kept f or t he t i me , c o s t , andequi pment used f or each t e s t f or i nput t o t hedevel opment of t hemai nt enance program Care shoul d bet aken t o ensure t h a t ext raneous i nf ormat i ondoes not become p a r t of t he record, because record keepi ngm ght hamper future use. Test report s gi vi ngt e s t descri pt i onand basi c procedure, components , drawi ng and other document ref erences, t e s t c i r c u i tdi agram, t e s t equi pment model and ageand c a l i b r a t i o n da t e , s pec i a l t o o l s requi red, t e s t f o rm w t hr e s ul t s f i l l e d i n, t i me t o r un t he t e s t , acceptance c r i t e r i a , f a i l u r e or unusual event i nf ormat i on,

recommended r e pa i r , andwhen t he t e s t shoul d be per f ormed agai n f or equi pment mai ntenance shoul d bedevel oped fo r the t e s t s . Summary l o gs devel oped f r omt he i nf ormat i on canbe used f or devel opi ng andschedul i ng an on- goi ngmai nt enance program Form shoul d be used t o document t he r e sul t s of test i ngprocedures . They shoul d be det a i l ed and di r e ct , but si mpl e and durabl e enough t o be used i n t he f i e l d .The fo rm shoul d be used as i nput t o t he devel opment of t he t e s t r e p o r t s . Awel l des i gned f o rmwi l lcont ai n checkl i st i nf ormat i on f or i n s pe ct i o ns , t e s t procedures, s a f e t y and speci al precaut i ons, requi redequi pment and t o ol s , ref erence draw ngs and manual s , acceptance c r i t e r i a , est i mat ed t i me t o perf ormt het e s t , and remarks / event recordi ngarea . Sampl e fo rm f or basi c equi pment and t e s t s are at t ached .f . Speci al precauti ons andsafety . Many t e s t s on el ec t r i c al equi pment i nvol vet heuseof hi gh vol t agesand currents t h a t are dangerous , both f r omt he st andpoi nt of bei ng l i f e hazards t o personnel and becausethey are capabl e of damagi ng or destr oyi ng theequi pment under t e s t . Adequate safety r u l es shoul d be

i ns t i t u t ed andpracti ced t o prevent i nj ury t o personnel , bot h personnel whoare per f orm ng t he t e s t s andothers whomght beexpos ed t o t he hazard . Al so, t he t e s t procedures used shoul d be des i gned t o ensuret h a t no i n t e nt i o na l damage t o equi pment wi l l r e s ul t from he t e s t i n g process . I t shoul d be recogni zed, ast hename i mpl i e s , t h a t over- potent i al or hi gh - p ot e n t i a l t e s t i n g i s i nt ended t o s t r e s s t he i nsul ati on s t r u c t u r eabove t h a t of normal syst emvol t age Thepurposeof t he t e s t i s t o es t a bl i s h t he i n t e g r i t y of t he i nsul ati ont o w t hstand vol t age t r a ns i e nt s ass oci ated w t h sw tchi ng and l i ghtni ng surges and hencereduce t heprobabi l i t y of i n - s e r v i c e equi pment f a i l u r e s . Di rect vol t age o ve r - po t e nt i a l test i ng i s general l y cons i dereda c on t r o l l e d, nondest ruct i ve t e s t i n t h a t an experi enced operator, u t i l i z i n g a s u i t a b l e t e s t s e t , can oftendetect margi nal i n s u l a t i o n f r omt he behavi or of measur ed current . I t i s t hereforepossi bl e, i n manycasest o d e t e c t quest i onabl e i nsul ati on and pl an f or repl acement w t hout ac t ua l l y breaki ng i t down under t e s t .Unf ort unat el y, some i nsul at i ons mght breakdownw t h nowarni ng Pl ans f or copi ngwi t h t h i sp o s s i b i l i t y shoul d be i ncl uded i n t he t e s t schedul e . Low- vol t age i n s u l a t i o n test i ng cangeneral l y be doneat the begi nni ngof t he pl annedmai ntenance s hut down . I n t he event of an i nsul ati on f a i l u r e under t e s t ,maxi mum i me woul d be avai l abl e f or repai r p r i o r t o t he sc hedul ed systemstartup Equi pment f ound i nwet or d i r t y condi t i on shoul d be cl eaned and dri ed bef ore h i g h- po t e nt i a l test i ng i s done or abreakdowncandamage t he equi pment . Low- vol t age c i r c u i t breakers, whi ch requi re very hi gh i nterrupt i ng r a t i n gs ,are a va i l a bl e w t h i n t e gr a l current- l i mti ng f uses . Al t hough thefuse s i z e i s sel ect ed t o overri dew thoutdamage t o t he t i me- current operat i ng c ha r ac t er i s t i c s of t he s er i e s t r i p devi ce, i t i s desi rabl e t o bypass orremove thefuse pr i o r t o appl yi ng si mul at ed overl oad and f a u l t current . I f a t e s t i n g program i s t o provi demeani ngf ul i nf ormat i on r e l a t i v e t o the condi ti onof t he equi pment under t e s t , then t he person eval uat i ng

TM-694

2- 5


14/104

TM- 694

t he t e s t d a t a must be ensur ed t ha t t he t e s t was conducted i n apr oper manner and that al l of t he condi ti onsthat coul d a f f e c t t he e va l ua t i o n of t he t e s t s wer e consi der ed and any p er t i n en t f a c t o r s r e p o r t e d . The t e s to p e r a t o r , t h e r e f o r e , must be t hor oughl y f a m l i a r w th t he t e s t equi pment used i n t he type of t es t t o beper f ormed and a l s o s u f f i c i e n t l y exper i enced t o be abl e t o de te c t any equi pment a bn or mal i t i es orques t i o na bl e data dur i n g t he per f ormance of t he t e s t s .g Te s t equi pment . I t i s i mp or t a n t that i n any t e s t programt he pr oper equi pment i s used . Theequi pment shoul d be c al i br a t e d, i n good c on di t i on , and used by qua l i f i ed o p e r a t o r s . Any t e s t equi pmentused f or c a l i b r a t i o n s hal l have tw c e t he accur acy of t he equi pment t o be t e s t e d . Car e shoul d be taken t ouse a qua l i t y or r e gul at e d power s o u r c e f or t he equi pment as v ol t a ge , f r equency, and wavef or mvar i a t i oncan pr oduce i n v a l i d r e s ul t s . Al l equi pment shoul d be o p e r a t e d i n accor dance w th i t s i n s t r u c t i o n manual .h Sampl e Comm ssi oni ng ( Cx) Pl an : Thepr i mar y i n t en t of t h i s t ec hn i c a l manual i s t o pr oposedi f f e r e nt pr ocedur es t h a t shoul d be consi der edwhencomm ssi oni ng anewel ec t r i c al systemand/ o r component . The f i gur e s , f or ms, and t e s t s i n t h i s manual a r e onl y exampl es of t he conceptst h a t shoul d be i mpl ement ed whendevel opi ng a comm ssi oni ng pl an . The f o l l ow n g par agr aphsdi scuss an exampl e of comm ssi oni ng programpl anni ng stages t h a t can beused t o commssi onanewsystemas shown i n f i g u r e 2 . 1 ( Comm ssi oni ng Pl an Exampl e) . The t i me per i od i n whi chacomm ssi oni ng process begi ns determnes what s t e p s i n t he pl anni ng stages a r e consi der ed :

( 1 ) I n i t i a l comm ssi oni ng ( k i c k - o f f ) meet i ng . The f i r s t comm ssi oni ng meet i ngmay s t a r t asear l y as bef or e a contract i s awar ded or as l a t e as a f t e r t he systemhas been i n s t a l l e d (before i t i sturned over t o t he cust omer ) . The pa r t i c i p an t s i n t he meeti ng shoul d i ncl ude cust omer ,gover nment contractor per sonnel , par ti c i pati ng engi neers, comm ssi oni ng per sonnel (maybe ani ndependent comm ssi oni ng contractor or gover nment engi neer ) , general c o n t r a c t o r , andel ec t r i c al and mechani cal sub-contractors . Topi cs of meet i ng shoul d i nc l ude ar eas ofr e s p o n s i b i l i t y , expectati ons, o ve r a l l presentat i on of system met hodol ogy, p ot e n t i a l pr obl ema r e a s , et c . The pa r t i c i p an t s shoul d be al l consi der ed " p a r t of a t eam" .( 2 ) Revi ew i n i t i a l st atement ofwork (SOW . Al l pa r t i c i pan t s shoul d r evi ewt he SOWha tdescr i bes the r equi r ements of t he comm ssi oni ng pr ocess . Thecust omer ( o r desi gnat ed author i t yshoul d have t he ul t i mat e control wher e deci s i ons a r e r equi r ed .( 3 ) Revi ewdr aw ng submt tal s . After t he syst ems a r e i n s t al l ed, dr aw ngs shoul d besubmtted f o r r evi ewand commnt . Somet i mes t he r evi ewmaybe before syst ems are i n s t a l l e d .Car e must be taken t o v e r i f y t h a t t he draw ngs submtted r e f l ec t t he a c t u a l i n s t a l l e d system( 4 ) Appr oval meet i ng . After t he SOWnd draw ng submt tal s have been submtted,r evi ewed, commntsmade, and comments i ncorpor at ed, appr oval of document s shoul d bepr ovi ded .( S) Syst ems oper at i on document ( SOD) / syst ems oper at i on andmai nt enance manual(SOMMocument . Pr i me contractor shoul d pr ov i de aSODor SOMMThese document s a r er equi r ed i n order t o devel op s p e c i f i c comm ssi oni ng t e s t s .( 6 ) Subm t f uncti onal per f or mance t e s t s (M) . Syst em component t e s t s or FPTs shoul dbe devel oped f r omsubmtted draw ngs, SODs and SOMM The t e s t s shoul d i nc l ude l arge

2-6


15/104

TM- 694

component t e st i ng ( i . e . t r ansf ormers , cabl e, gener at or s, UPS), andhowcomponents operat e aspart of t he t o t a l system Thet e s t shoul d bedevel oped by t he commssi oni ng aut hori t y . Thecommssi oni ngaut hor i t y shoul d not be t he i ns t al l at i on contractor ( or sub-contractor) .

( 7) Qual i t y assurance . As t he equi pment / component s / syst ems ar e i ns t al l ed qual i t yassurance procedures shoul d be adm ni st e red t o ver i f y components ar e i ns t al l ed i n -accordancew thmnimummanuf act ur er s r ec ommendat i ons , safety codes, andaccept abl e i ns tal l at i onpract i ces . Qual i t y assur ance di scr epanci es shoul d be i dent i f i ed andaddedt o a "commssi oni ngact i on l i s t " t h a t must be r e c t i f i e d as pas t of t he commssi oni ngprogramThese i t ems wou dusual l y bedi scussed dur i ng commssi oni ngmeet i ngs . D sc repanc i e s ar e usual l y i dent i f i edi n i t i a l l y by vi sual i nspect i on .

( 8) Revi ewFPTs . The t e s t s shoul d be revi ewedbyt he cust omer , el ectr i cal contractors,qual i t y assurance pers onnel , mai nt enance pers onnel , et c (the commssi oni ng team. Areas ofconcernshoul d be 1) ar e al l f unct i ons of t he systembei ng tested, 2) ar e al l maj or componentsi ncl uded, 3) do t he t e s t s ref l ect t he systemoperati ng document s , 4) do t he tes tsmake sense, et c .

( 9) Make changes t o FPTs . Thi s i s wherecorr ect i ons, quest i ons answer ed, andaddi t i onsmade w l l be i mplemented Thi s w l l bedoneby t he commssi oni ngaut hor i t y .

(10) FPT appr oval . After t he changes ar emade t o t heFPTs t hey w l l agai n besubmt t ed t ot he commssi oni ngteamWen i t i s accept abl e t he customer or hi s/ her desi gnat ed appr ovalaut hori t y shoul d appr ove t he FPTs . I t shoul d be not ed t hat eventhought heFPT s approved,probl em t hat ar i s e dur i ng t he t e s t ( or areas not covered) shoul d be addressed

(11) Syst ems operat e . TheFPTs canbe i mplemented as vari ous system becomeoperat i ve( i . e . t e s t t he generat or sys tem orwhen t he ent i re system s i ns t al l ed . However the f i na l "pul l t hepl ug" t e s t w l l beperformedafter al l syst ems ar e compl ete l y i ns t al l ed . I f t he FPTs ar ei mpl ementedbyt he el ectr i cal contractor ( or sub-cont rac tor) t hen aw tn es s shoul d i n i t i a l eachs tep of t he t e s t . Thew t nes s shoul d not beempl oyed di r ec t l y or i ndi rec t l yby t he el ectr i calcontractor .

(12) Cust omer r ecei ves syst em After al l t e s t s ar e completed ( i nc l udi ng the "pul l t he pl ug"t e s t ) t he system shoul d be t ur ned over t o t he customer .


16/104

TM5- 694

2- 8

I n i t i a l CxMeeti ng

2- 4 . I nsul at i on test i ng

Commssi oni ng (Cx) Planni ng StagesRevi ewI n i t i a lSOW

Devel opment OF Functi onal Perf ormance Tests (FPT' s)

2- 3 . Typesof test i ng methods

Revi ewFPT' s MakeChangesto FPT' s

Testi ng Imp ementati on

ApprovalMeeti ng

FPT' sApproved' "-

Fi gure 2- 1 . Sampl e of acommss i oni ngpl an

CustomerRecei vesSystem

Types of test i ngmet hods i ncl ude t he f our cat egori es of t e s t s as wel l as t he t e s t s t hemel ves .a Categor i es of t e s t s . Ther e are four categor i es of t e s t s f or e l e c t r i c a l equi pment ; f a c t o r y , accept ance,rout i ne mai nt enance, and speci al mai nt enance . Fact ory t e s t s ar e per f ormed a t t he f act ory t o prove t heequi pment wasmanuf act ur ed properl y and meet s s p e c i f i c desi gn par amet er s . Commss i oni ng t e s t s , t hemai n subj ect of t h i s document , ar e a l s o proof t e s t s per f ormed on newequi pment and system usual l y a f t e

i n s t a l l a t i o n andbefore energi zat i on . They ar e r un t o determne whet her t he equi pment i s i n compl i ancew t h s p e c i f i c a t i o n s , t o e s t a b l i s h benchmar ks f or future t e s t s , t o det ermne t he equi pment was i n s t a l l e dcorr ect l yandw t hout damage, and t o ver i fy whet her t he equi pment meet s i t s i nt ended desi gn operat i onand l i m t s . Rout i ne and speci al mai nt enance t e s t s ar e r un a f t e r t he equi pment has been i n servi ce f or acertai n amount of t i me t o det ermne t he degree of de t e r i o r a t i on of c e r t a i n equi pment physi cal par amet er sas operat i ng t i me i ncreases . Rout i ne t e s t s ar e per f ormedonaperi odi c basi s and s p ec i a l t e s t s ar eper f ormed on def ect i ve equi pment t o hel pdet erm ne t he cause of af a i l u r e and/ or t he ext ent of t hedamage Thesame t ype of t e s t s andmeasur ement s ar e per f ormed f or al l of t he cat egori es usi ng d i f f e r e n tvol t age val ues . Theaccept ance t e s t s ar e usual l y r un a t 80%nd t he mai nt enance t e s t s are usual l y r un a t60%f t h e factory t e s t vol t age val ues t o hel p i n d i c at e de t e r i o r a t i on w thout bei ng destr ucti veb Types of test i ngmet hods . The t e s t i n g of e l e c t r i c a l power systemequi pment i nvol ves checki ng t he

i nsul at i on adequacy, e l e c t r i c a l pr o p er t i e s , prot ect i on and c ont r o l , operat i on, andother i t em as t hey r e l a tt o t he o ve r a l l system Some of these checks ar e accompl i shed usi ng de-energi zed component t e s t s ,i ns t rumntat i on and re l ay operat i on andcal i brat i on t e s t s , energi zed f unct i onal t e s t i n g of contr ol c i r c u i t s ,megger t e s t i n g of power c i r c u i t s , phase out test i ng of power c i r c u i t s , andserv i ce t e s t i n g .

I nsul at i on can e i t h e r be s o l i d , l i q u i d , or gaseous d i e l e c t r i c mater i al s t h a t pr event t he f l owof e l e c t r i c i t ybet ween poi nt s of d i f f e r e n t po t e nt i a l . I nsul at i on test i ng i s per f ormed t o determne t he i n t e g r i t y of t he


17/104

c Di r ect- cur r ent (dc) testi ng . Whenado p ot e n t i a l i s appl i ed across an i n s u l a t i o n , t he r e s u l t a ntcurrent f l o w i s composed of several component s as f ol l ows :

TM- 694

i nsul ati on . Thi s usual l y c o n s i s t s of appl yi ng ahi gh p ot e n t i a l vol t age t o t he i t emandmeasur i ng t hel eakage current t h a t mayf l o wt o gr ound . Excessi ve l eakage current i s an i ndi cati on of d i e l e c t r i cbreakdown and/ or i mpendi ng f a i l u r e . I nsul ati onmayweaken over t i me at a r a t e t i g h t l y r e l at e d t o t heoperat i ng t i me and t emperat ure of operat i on. Ther ef ore, these t e s t s ar e r un peri odi cal l y t o t rack t hei nsul ati on d e t e r i o r a t i o n . I nsul ati on t e s t i n g , t he most commonel e ct r i c al testi ng perf or med, can beper f or med by appl yi ng ad i r e ct current ( d c ) or a l t e r nat i ng current ( a c ) vol t age Thetype andval ue of t hevol tage determnes whet her t he t e s t i s consi der ed nondest ruct i ve or dest ructi ve. The hi gher t he vol t age,t hemoredest ruct i ve t he t e s t . Usual l y dest ructi ve t e s t s ar e onl y r un one t i me i n t h e factory t o veri f y t hei n i t i a l strength of t he i n s u l a t i o n , and nondest r ucti ve t e s t s ar e r un as acceptance and mai nt enance t e s t s t omeas ur e d e t e r i o r a t i o n f r o mt he o r i g i na l val ue . Bot h t hedo and ac t e s t s ar e "gono- go" t e s t s . I n a dd i t i o n,t he do t e s t can i ndi cate t he amount of d et e r i o r a t i on and f orecast t he r emai ni ng t i me f or s af e operat i onbycompar i ng t he l eakagecurrent and t e s t vol t age t o val ues f r o mprevi ous t e s t s .a Advantageof di rect - curr ent testi ng . D rect- curr ent t e s t i s pref er r ed onequi pment whosechar gi ngcapaci t ance i s very hi gh, such as cabl es . D rect- curr ent vol t age s t r e s s i s consi der ed muchl e s s damagi ngt o i nsul ati on than ac vol tages . Thet i me of vol t age appl i cati on i s not as c r i t i c a l w t h do vol t age as w t h acvol tage. The t e s t can be st opped bef ore equi pment f a i l u r e . Meas ur ement s canbe taken concur rent l y . I t

i s not necessary t o makea separate i nsul ati on r e s i s t a n c e t e s t pr i or t o maki ng ado over p ot e nt i a l t e s t .b D sadvantageof di rect- curr ent testi ng. The s t r e s s d i s t r i b ut i on f o r t r ansf ormers, mot or s, andgener at or wi ndi ng i s d i f f e r e nt f o r do vol t age than f or ac vol t age . Ther esi dual charge a f t e r ado vol t age

t e s t must be caref ul l y di schar ged . Thet i me r equi r ed t o conduct ado hi gh-pot ent i al t e s t i s l onger than f oran ac hi gh-pot ent i al t e s t .

( 1) Capaci t ance- chargi ng current . Capaci t ance- char gi ng current i s t he current r e s u l t i n g f r o mcharge absor bed by t he capaci t or f or med by t he capaci t ance of t he bushi ng . Thi s current i s a f uncti on oft i mewh chal so depends on appl i ed do vol t age, i n s u l a t i o n resi st ance andt he t i me const ant of t he c i r c u i t .( 2) D el ectri c-absorpti on current . D i e l e c t r i c - a b s o r p t i o n c u r r e n t i s t he current t h a t i s absor bed and trappedi n t he d i e l e c t r i c duri ng t he char gi ng of the p i e ce of equi pment and r e l e as e d a f t e r t he equi pment i s di scharged .Thi s c u r r e n t can be c al c ul a t e d f r o m es t v ol t a g e, c ap ac i t a n ce , and t i me . I n a i r - c o o l e d and hydrogen- cool ed acr o t a t i n g machi nes, d i e l e c t r i c absorpti onv a r i e s w t h t emperat ure( 3) Sur f ace l eakage current . Thepassage of current over the surf ace of an i nsul ati on rather thanthrough i t s vol ume i s surface l eakage cur r ent . I n measur i ng i nsul ati on resi st ance of ar mat ure and f i e l dw ndi ngs i n r o t a t i n g machi nes (rated 1 hp, 750Wr g r e a t e r ) , ahi gh sur f ace l eakage current i s usual l ycaused bymoi st ur e or anot her type of partl y conducti ve cont amnati on present i n t he rotati ng mach i ne .( 4 ) Part i a l di scharge ( cor ona current) . Thi s i s a type of l ocal i zed di scharge r e s u l t i n g f r o mt ransi ent gaseous i oni zati on i n an i nsul ati on systemwhent he vol t age s t r e s s exceeds a c r i t i c a l val ue .

P ar t i a l di scharge i s not desi rabl eandshoul d be el i mnated . I t i s caused by overst ressi ng of a i r at sharpcorners of t he conduct or due t o hi gh t e s t vol t age I n shi el ded power cabl e system ( r a t e d >5 kV) ,humdi t y or wnd can i ncrease t he corona current .( 5) Vol umet r i c l eakage current . The c u r r e n t t h a t f l ows through t he vol ume i n s u l a t i o n i t s e l f i s vol umet r i cl eakage c u r r e n t . I t i s t he c u r r e n t t h a t i s of pri mar y i n t e r e s t i n t he eval uati on of t he condi ti on of t he i n s u l a t i o n . I nshi el ded power cabl e system ( r a t e d >5 kV) , humdi t y, c o nd e ns a t i o n, and p r e c i p i t a t i o n on t he s u r f a c e of a

termnati on can i nc r e as e s u r f a c e l eakage c u r r e n t and vol umetr i c l eakage c u r r e n t . Sur f ace l eakagecurrent and

2- 9


18/104

TM- 694

vol umetr i c current added t o g e t h e r i s t he q uo t i e nt of t he appl i eddo v ol t a g e and i n s u l a t i o n r e s i s t a n c e . I n l a r ge acr o t a t i n g machi nes r a t e d 10, 000 kVAor g r e a t e r and r a t e d 6000Vr h i g he r , mo i s t u r e , ont he endw ndi ngs,i n cr e as es s u r f a c e l eakage c u r r e n t and vol umetr i c l eakage c u r r e n t e s p e c i a l l y when d i r t i s a l s o ont hewi ndi ngSi nce t he i n s u l a t i o n mayweakenover t i me , agemaycause an i n c r ea s e i n t he var i ous c u r r e n t s dur i ng t e s t i n g .d I nsul at i on- r es i s tance ( megger ) t e st i ng . For equi pment contai ni ng el ec t roni c component s, meggert est i ng must not be per f or med However , t h i s equi pment shoul d be tested accordi ng t o manuf act ur er

s pec i f i c at i on s . I n an i nsul at i on-r esi stance t e s t , an appl i ed v ol t a ge , f r o m600 t o 5000 v o l t s , suppl i ed f r omasource of const ant p ot e nt i a l , i s appl i edacross t he i nsul at i on . The usual p ot e nt i a l source i s amegohmet er , al soknownas amegger , e i t he r hand or power oper at ed t h a t i ndi cat es t he i nsul at i onresi stance d i r e c t l y on a s c al e cal i br at ed i n megohm. Amegohmet er t hat i s ahand cr anked, a r e c t i f i e r -t ype, or bat tery- operat ed i nst r ument i s s u i t a b l e f or t est i ng equi pment rated up t o 600vol t s . Forequi pment r at ed over 600 v o l t s , use of a 1000- vol t or 2500- vol t motor - dr i ven or r e c t i f i e r - t y p emgohmter i s recommndedf or opt i mumes t r e s u l t s . Thequal i t y of t he i nsul at i on i s eval uat ed based ot he l e ve l of t he i n s u l a t i o n r esi stance . The i n s u l at i on r e s i s t a nc e of many types of i nsul at i on i s var i abl ewi t h t emperat ur e, so t he dat a obt ai ned shoul d becorrected t o t he st andar d t emperat ur e f or t he c l a s s ofequi pment under t e s t . Publ i shed charts s i m l a r t o t a b l e 2- 1 ar e avai l abl e fo r t h i s purpose . Themegohmval ue of i nsul at i on resi stance obt ai ned wi l l be i nver sel y propor t i onal t o t he vol ume of i nsul at i on bei ngtested . For exampl e, a cabl e 1000- f t (304 . 8 m l ong woul dbe expect ed t o have one-tenth t he i nsul at i onresi stance of a cabl e 100-ft ( 30. 48 m l ong i f al l ot her condi t i ons wer e i de nt i c a l . The i nsul at i on-r esi stanct e s t i s r e l a t i v e l y easy t o performand i s a u s e f u l t e s t used on al l types andcl asses of e l e c t r i c a l equi pment .I t s mai n val ue l i e s i n t he char t i ng of data f r omperi odi c t e s t s , corrected f or t emperat ur e, over t he l i f e oft he equi pment so t h a t det er i orat i ve trends m ght be detected .

Not es : kVi s t he ratedmachi net erm nal t o t erm nal v ol t a ge , i n r ms (root mean squar e) kVRecommendedmni mum nsul at i on r e s i s t a n c e val ues above, i n mgohm, at 40Cof t he e n t i r e machi newi ndi ng f or overvol t age test i ng or operat i on of ac anddo machi ne s t a t o r wi ndi ngs androtor wi ndi ngs .FromEEESt d . 43- 2000 . Copyr i ght C2000 I EEE Al l r i g h t s reserved .e Di el ec t r i c absorpt i on test i ng I n a d i e l e c t r i c - a b s o r p t i o n t e s t , avol tage suppl i ed f r omasource of c o n s t a n t

p ot e n t i a l i s appl i edacross t he i n s u l a t i o n . Thet e s t vol t age usedmayhave t o be s i g n i f i c a n t l yhi gher t han t hei n su l a t i on - r e s i s t a nc e t e s t i n or der t o ob t ai n measur abl e c ur r e nt r e a di n gs . The p ot e nt i a l source can be e i t he r ameg- ohmmet er , as descr i bed above or ahi gh- v ol t a g e power suppl y wi t h an ammet er i n d i c a t i n g t he current bei ndrawnby t he speci men under t e s t . Thevol t age i s appl i edf or an extended peri od of t i me, f r om5 t o 15 m nut es,and p er i od i c r eadi ngs ar e t aken of t he i n s u l a t i o n r e s i s t a n ce or l eakage current . The t e s t d a t a i s eval uat edon t heb as i s tha t i f an i n s u l a t i o n i s i n good c on di t i o n, i t s appar ent i n s u l a t i o n r e s i s t a nc e wi l l i n c r e as e as t he t e s tprogresses . Unl i ke t he i n su l a t i on - r e s i s t an ce t e s t , t he di e l ec t r i c - a bs or p t i on t e s t r e s u l t s ar e i ndependent of t hevol ume and t he t emperat ur e of t he i ns ul at i on under t e s t . For t he d i e l e c t r i c absorpt i on t e s t , t he val ues recorded aeach one mnute i n t e r v al are p l o t t e d on l o g - l o g paper wi t h c o or d i n at e s f or r e s i s t a nc e versus t i me . The sl ope oft he r e s u l t i n g curve g i v es agood i n d i c a t i o n of t he i n s u l a t i o n condi t i on Aood i n s u l a t i o n systemwi l l have a

2- 10

Tabl e 2- 1 Recommendedmni mum nsul at i on r esi s tance val ues at 40C( a l l val ues i nMMnimumnsul at i on Resi st ance a f t e r 1 mnute Test speci men(MI ) kV+ For most wi ndi ngs made before about 1970, al l( Exampl e : 15 kVmachi ne i s 1 S+1=16 MS2) f i e l d w ndi ngs, andothers not descr i bed bel ow

For most do armatur e andac wi ndi ngs b u i l t a f t e r100 about 1970 ( f or m- wound c o i l s )For most machi nes wi t h randomwounds t a t o rc o i l s and f or m- wound c o i l s rated bel ow 1 kV


19/104

s l o pe t h a t i s as t r a i g h t l i n e i n cr e as i n g i n r e s p e c t t o t i me. Thec h a r a c t e r i s t i c s l o pe of apoor i n s u l a t i o n systemw i l lbeacurve t h at f l at t e ns out wi th r e s p e c t t o t i me.f Pol ar i zat i on i ndex t e s t i n g . Thep o l a r i z a t i o n i ndex i s aspeci al i zed appl i cati on of t he d i e l e c t r i cabsor pt i on t e s t . The i ndex i s t he r a t i o of i n su l a t i on r e s i s t an ce a t two d i f f e r e n t t i mes a f t e r vol t ageappl i cat i on, usual l y t he i nsul ati on resi stance a t 10 m nut es t o t he i n s u l a t i o n r esi st ance a t 1 mnute . Theuse of pol ari zat i on- i ndex t e s t i n g i s usual l y conf i ned t o r o t a t i n g machi nes, cabl es, and t r ansf ormers . Apol ari zati on i ndex l e s s than 1 . 0 i n di c at e s t h a t t he equi pment needs mai nt enance befor e bei ng pl aced i nservi ce . Ref erences ar e avai l abl e f or pol a r i z at i on i ndexes f or var i ous types of equi pment as wel l as i nt a b l e 2- 2 . Accept ance t e st i n g s pec i f i c at i on s f o r E l ec t r i c al Power andDi stri buti on Equi pment andSyst ems NETA1999 andRecommendedPracti ce f o r Testi ng I nsul ati on Resi st ance of Rot ati ngMachi nery ( I EEE St d . 43- 2000) are references avai l abl e f or p o l a r i z a t i o n i ndexes f or var i ous t ypes ofequi pment . Thepol ari zati on i ndex t e s t l a s t s f or 10 m nut es . The i n s u l a t i o n r esi stance i s recorded a f t e r 1mnute , then agai n a f t e r 10 m nut es. Thep o l a r i z a t i o n i ndex i s t he quot i ent of t he 10-mnute and 1 mnuter eadi ngs as shown i n t he f ol l owi ng equat i on :Where

Where

PI =RI O/ R, ( di mensi onl ess)PI =pol ari zati on i ndexR=esi stance

For pol ari zati on i ndexes i n t r ansf ormers anacceptabl e val ue woul dbe 2or hi gher , val ues between 2and 1i ndi cate mar gi nal condi t i on, and val ues bel ow 1 i n di c at e poor condi t i on . Af t er i nsul ati on resi stancer eadi ngs have been made, t he t e s t vol t age i s returned t o zero and t he i n s u l a t i o n i s di schar ged .g H ghpot ent i al t e s t i n g . Ahi gh-pot ent i al t e s t ( h i - p o t ) c on s i s t s of appl yi ng vol t age across an

i nsul ati on a t or above t he do equi val ent of t he 60-Hzoperat i ng c r e s t vol t age Thedo equi val ent of t he 60-Hzoper ati ng c r e s t vol t age i s cal cul at ed usi ng t he f ol l owi ng equat i on :Vac=Vdc/ 42-Vdc i s t he equi val ent do vol t ageVac i s t he oper ati ng c r e s t ac vol t age

Theh i - pot t e s t canbe appl i ed e i t h er as ad i e l e c t r i c - a b s o r p t i o n t e s t or as t e p- v ol t a ge t e s t . DChi gh p ot e n t i a l t e s t sar e "go no- go" t e s t s . Thecabl e i s r e q ui r e d t o wi t hstand t he s p e c i f i e d vol t age f o r t he s pec i f i ed t i me dur ati on .These t es t s wi l l normal l y r e v e a l maj or probl ems due t o i mproper f i e l d h an dl i n g, i mpr oper l y i n s t a l l e d a c ce s s or i e sor mechani cal damage . Recommendedt e s t v ol t a g es a r e gi ven i n s t a n d a r d t a bl e s f or do and ac . Toperformt hedoHi - pot t e s t t hei nput vol t age t o t he t e s t s et shoul d be r egul ated Thecurrent sensi ngc i r c u i t s i n t e s t equi pments h a l l measur e onl y t he l eakage c u r r e n t associ atedwi th t he c a bl e under t e s t and s h a l l not i ncl ude i n t e r n al l eakageof t he t e s t equi pment . Recordwetbul b and dr y-bul b t emper atures or r e l a t i v e hum di ty and t emper at ure Thewetbul b t emper at ure i s def i ned as the t emperat ure gi venbyat her momet er bul bwhi ch i s coveredwi th an absorbentma t e r i a l ( l i n e n wetwi th d i s t i l l e d water) and exposed t o t heat mosphere so t h a t evapor ati on w i l l cool t hewat erand t he t hermomet er bul b Thedr y-bul b t emperat ure i s defi ned as the t emperat ure of t he at mosphere gi venbyanor di nary t hermomet er . Test each s ec t i o n of c ab l e i n d i v i d u a l l y wi th al l ot her conductors grounded. Al l s h i e l d smust a l s o be grounded . Term nati ons s h al l be adequat el y coronasuppressed byguard r i n g , f i e l d r educt i ons p he r e , or ot her s u i t a b l e met hods as necessary Precaut i on shoul d be taken t o i n su r e t h a t t hemaxi mumes tvol t age does not exceed t he l i m t s f or t e r m n at i on s s pec i f i ed i n I EEESt andard 48 or manuf act urers s pec i f i c at i on s .When appl i ed as adi el ec t r i c - a bs or p t i on t e s t , t hemaximumol t age i s appl i ed gr adual l y over aper i od of f rom60t o 90 seconds . Themaximumol t age i s then hel d f o r 5mnutes wi th l e ak ag e- c u r r e nt r eadi ngs bei ngtaken each

TM- 694

2 - 11


20/104

TM- 694

mnute. I n c a bl e s , hi gh ambi ent t emperat ure o r hum di ty at t heends of i mproper l y prepar ed c a bl e s can r a i s e t hedo l eakage current t o many t i mes i t s nor mal val ue Whenappl i ed as a s t e p - v o l t a ge t e s t , t he maximumvol t age i sappl i ed i n anumber of equal i ncrement s, us ua l l y not l es s than e i g ht , wi th each vol t age s t e p bei ng hel d f o r anequal i n t er v al of t i me. Ay pi c a l vol t age ver sus t i me gr aphas showni n f i g u r e 2- 2 . The t i me i n t er v al betweens t e p s shoul d be l ong enough t o al l owt he l eakage c u r r e n t t o r each s t a b i l i t y , appr oxi matel y 1 or 2mnut es. Al eakage- cur r ent r eadi ng i s taken at t he end of each i n t er v a l before t he vol t age i s r a i s e d t o t he next l e ve l .

Apl ot of t e s t vol t agever sus l eakage curr ent or i nsul ati on r esi stance i s drawn as t he t e s t pr ogr esses . Anonl i near i ncr ease i n l eakage current can i nd i c at e i mm nent f a i l u r e , and t he t e s t shoul d be di sconti nued .See f i gure 2- 3 .

2- 12

4 8 12 t i me ( m n )

Fi gure 2- 2 St ep- vol t age ver sus t i me

cmYmJ

Nobreakdowns i ni nsul at i on system I

Vol tage(kV)

Breakdownof~~"i nsul at i on system

Fi gur e 2- 3 St ep- vol t age hi ghpot ent i al t e s t currentAfter t hemaxi mumes t vol t age i s r eached, a d i e l e c t r i c absor pti on t e s t can be per f or med at t h at v ol t a ge ,usual l y f or a5-mnute per i od .h AChi ghpot ent i al test i ng Al ternat i ng- curr ent hi gh- pot ent i al t e s t s ar emade at vol t ages above t henor mal systemvol t age f or a s ho r t t i me, such a 1 mnute . The t e s t vol tages to be used var y dependi ng onwhet her the devi ce or c i r c u i t i s l owor hi gh v o l t a ge , apr i mar y or control c i r c u i t , andwhet her i t was t e s t e


21/104

a t t he f ac tor y or i n t he f i e l d . Manuf act urer s' i n s t r u c t i o n s and t he appl i cabl e st andar ds shoul d be consul t edf or t he pr oper val ues .i . I n s u l a t i o n powerfactor t e s t i n g . Thepower f a c t o r of an i ns ul a t i on i s ameas ur e of t heenergy componentof t he chargi ng c u r r e n t . Power- f actor t e s t i n g i s used t o det erm ne t he power f a c t o r of an i n s u l a t i o n systemPower- f actor t e s t i n g i s au s ef u l t o o l i n e va l u a t i n g t he q u a l i t y of i n s u l a t i o n i n power , d i s t r i b u t i o n , and i nst r umentt r ansf ormers ; c i r c u i t b r e a k e r s ; r o t a t i n g machi nes, cabl es ; r e g ul a t o r s ; and i ns ul a t i ng l i qui ds . Theequi pment t o bet e s t e d shoul d be i s o l a t e d f r o mt he r e s t of the system i f p r a ct i c al , and al l bushi ngs or t e r m na t i ons shoul d becl eanedand d r i e d . The t e s t shoul d be conduct edwhent he r e l a t i v e humdi t y i s be l ow70 percent andwhent hei ns ul a t i on systemi s a t a t emperat ure above 32F ( 0C) . The t e s t equi pment usedshoul d be such t h a t t hepowerf a c t o r or d i s s i p a t i o n f a c t o r can be r e a d d i r e c t l y or such t h a t t he char gi ng vol t - amper es and t he d i e l e c t r i c l o ss e s canbe r e a d s e pa r a t e l y so t h a t ar a t i o mght be comput ed Thet e s t equi pment shoul d a l s o have s u f f i c i e n tel ect r omagnet i c i n t e r f e r e n c e c an ce l l a t i on devi ces or s hi e l d i ng t o gi ve meani ngf ul t e s t r e s u l t s evenwhenused i nan a r e a of strong i n t e r f e r e n ce , such as an energi zed s ub s t a t i o n . El ect r omagnet i c i n t e r f e r e n c e d i s t o r t s t he r e a d i n gs ,y i e l d i n g i nc or r e ct val ues . Thed es i r e d measur ement s shoul d be per f ormedf ol l owi ng t he o pe r a t i n g i n s t r u c t i o n ssuppl i edwi th the t e s t equi pment . The l e a d connect i onsmayhave t o be changed s e v e r a l t i me s , dependi ng on t hecompl exi t y of t he a p p a r a t u s and t e s t equi pment . Ameani ngf ul e va l u a t i o n w i l l i ncl ude compar i son t omanuf act ur er' s r e s u l t s taken at t he f a c t o r y and/ or namepl at e d a t a . Ont r ansf or mer t e s t s , o b t a i n t hepower f a c t o rof each wi ndi ng wi th r e s p e c t t o ground and each wi ndi ng wi th r e s p e c t t o each o t h e r wi ndi ng I n a d d i t i o n , t e s t sshoul d be madeof each bushi ng wi th ar a t e d vol t age above 600v o l t s , e i t he r usi ng t he power f a c t o r or capaci t ance

t a p i f t he bushi ng i s so equi ppedor by use of a" h o t - c o l l a r " t e s t usi ngat e s t e l e ct r o de ar ound t he out si de s he l l oft he bushi ng. Onhi gher vol t age c i r c u i t b r e a k e r s , t hepower f a c t o r of each l i n e - s i d e and l o a d - s i d e bushi ngassembl y compl et e wi t h s t a t i o na r y contact and i n t e r r up t e r s , wi th the c i r c u i t breaker open, and each p ol e of t hec i r c u i t breaker wi t h the breaker cl osed shoul d be obt ai ned Onac r o t a t i n g machi nes, t he n e u t r a l connect i on ont he s t a t o r shoul dber emoved andat e s t of each wi ndi ng wi t h r e s p e c t t o t he other t wo wi ndi ngs and gr ound shoul dbe obt ai ned For c a bl e s , t he power f a c t o r of each conduct or wi th respect t o ground shoul d be obt ai ned and ah o t -c o l l a r t e s t shoul d be made of each pot head or t erm nat i on . Power- f actor t e s t i n g of i n s u l a t i n g oi l shoul d beper f or med i n accor dance wi t h Amer i can Soci et y f or Tes t i ng and Mat eri al s (ASTMD24 , St andard TestMet hod f or Di ssi pat i on Factor (orPower Factor) andRe l a t i v e P e r m t t i v i t y ( D i e l e c t r i c Const ant ) of E l e c t r i c a lI n s u l a t i n g Li qui ds .

2- 5 Swi t ch/ c i r cui t br eaker test i ng

TM- 694

I n a d d i t i o n t o t he i ns ul a t i on t e st i ng ment i onedabove, f or l a r g e sw tches and c i r c u i t b r e a k e r s t he f ol l owi ng t e s t scan be appl i ed.a Ci rcui t breaker t i me-t r avel anal ysi s . Thi s t e s t , used on medi umandhi gh- vol t age c i r c u i t breakersprovi des i nf ormat i on as t o whet her t he operat i ng mechani smof t he c i r c u i t breaker i s oper at i ng pr oper l y .Thi s t e s t can be used t o determne t he openi ng andc l os i ng speeds of t he breaker, t he i n t e r va l t i me f orc l os i ng and t r i p p i n g , and t he contact bounce . The t e s t provi des i nf or mat i on t h a t can be used t o det ectpr obl ems such as weak accel er ati ng s p r i n gs , defecti ve shock absorbers, dashpot s, b u f f e r s , and c l os i ngmec hani sms . The t e s t i s per f or medby amechani cal devi ce t h a t i s att ached t o t he breaker . Onedevi ce, ar o t a t i n g drumwi t h a chart at t ached, i s t empor ari l y connect ed t o the chassi s or tank of t he breaker . A

movabl e r od wi t h amar ki ng devi ce att ached i s i n s t a l l e d on t he l i f t r od por t i onof t he br eaker . As t hebreaker i s opened or cl osed, t he mar ki ng devi ce i ndi cat es t he amount of contact t r a v e l ont he chart as t hedrumo t a t e s at aknownspeed. W t h anot her avai l abl e devi ce, a t r ansducer i s attached t o t he mvabl er o d , and t he breaker operat i on i s recorded on an osci l l ograph .b Cont act - r esi stance t e s t i n g . Thi s t e s t i s used t o t e s t t he q u a l i t y of t he contacts on swi t ches and

c i r c u i t breakers . Aes t s e t desi gned f or t h i s purpose i s ava i l a b l e wi t h di rect - scal e c a l i b r a t i o n i nm cr ohms, capabl e of r eadi ng cont act r esi stances of 10 m cr ohms or l e s s . An a l t e r n a t e met hod i s t o pass a

2- 13


22/104

TM- 694

known l e ve l of di rect current t hr ough t he cont act s t r u c t u r e s and t omeasur e t he do ml l i v o l t drop acrosst he cont acts . Thedata obt ai ned can t hen be convert ed t o r esi st ance by appl yi ng OhmsLaw Thea l t e r n a t e method r equi r es asour ce of at l e as t 100 amper es w t h am l l i v o l t met er of appr oxi mat el y 0- 20mVr ange .2- 6 Transformer test i ngTr ansf ormer s ar e subj ect t o t he f ol l ow ng t e s t s i n addi t i on t o t he i nsul at i on test i ngment i oned above i npar agr aph 2- 4 However , dr y- t ype t r ansf ormrs woul dnot be subj ect t o f a u l t - g a s anal ysi s and i nsul at i ngl i q u i d anal ysi s due t o t he f a c t t h a t t hese t ypes of t ransformrs usual l y fea tureagaseous or dr y compoundi nsul at i ngmedi um Cast c o i l transformrs, whi ch ar e de f i ned as a t r ansf orm r w t h hi gh- vol t age c o i l scast i n an epoxy r e s i n , woul da l s o not be subj ect t o f a u l t - g a s anal ysi s and i nsul at i ng l i qui d anal ysi s due t ot he f a ct t hat t he core and c o i l s of t hese t ypes of t ransformrs are not i mmer sed i n an i nsul at i ng l i q u i d .Cast c o i l t ransformrs ar e consi der ed t o be dry-type t ransformrs .a Rcmformer t u rns- r at i oandpol ar i t y t e s t s . Thet u r n s - r a t i o t e s t i s used t o determne t henumber of t u r n s i none w ndi ngof atransformr i n r e l a t i o n t o t he numbe r of t u r n s i n t he o t h e r w ndi ngs of t hesame phase of t hetransformr . Thep o l a r i t y tes t det ermnes t he v e c t o r a i r e l a t i o n s h i p of t he var i ous t ransf ormr w ndi ngs . Thet e s t s

ar e appl i cabl e t o al l power and d i s t r i b u t i o n t r a ns f o r me r s . See f i g u r e 2- 4 f or ad i agr amof at y p i c al f l u i d f i l l e dpower t ransformrs . Cast c o i l transformrs ar e a l s o s u bj e c t t o t heset e s t s . Thet u r n s - r a t i o t e s t and t he p o l a r i t y t e scan be done ont ransformrs of al l s i z e s . Thet u r n s - r a t i o t e s t i s a l s o commonl yper formd on i nst r umnttransformrs . Thet e s t equi pment used wi l l or di n ar i l y be at u r n s - r a t i o t e st s et desi gned f o r t hepurpose, al t hough,i f not a va i l a bl e , twovol t mters or t wo ammet er s ( f o r c u r r e n t transformrs onl y) can be used . Whent wo acvol t mters are used, onei s connect ed t o t he h i g h- v ol t a ge w ndi ng and t he ot her i s connect ed t o t he l owvol t agew ndi ng Thehi gh vol t age w ndi ng i s exci t ed t o avol t age not exceedi ng t he r a t i n g of t he vol tmt er . Bot hvol t mters ar e read si mul t aneousl y . Aecond s et of r eadi ngs shoul d be takenw t h t hemte r i ng i nst rumnt si nt er changed . Theval ues i n d i c a t e d shoul d be aver aged t o c al c ul at e t he r a t i o . Amani ngf ul r a t i o measur ementmaybemadeusi ng onl y afewv o l t s of e x c i t a t i o n . Thetransformr shoul d be exci t ed f r omt hehi ghest vol t agew ndi ng i n order t o avoi d p os s i b l y unsaf e hi gh v ol t a ge s . Car e shoul d be taken dur i ng t he a p p l i c a t i o n of vol t ageand dur i ng t hemeasur ement . I t i s i mpor t ant t ha t si mul t aneous r eadi ngs f or bot h vol tmt ers be made Thevol tmt ers used shoul d have accur acy' smat chi ng w t h t he r equi remnt s of a0 5%a t i o c a l c u l a t i o n . Whenat u r n s - r a t i o t es t i s perf ormd, t he r a t i o shoul d be determned f or al l no- l oadt a p s . I f t he transformr i s equi ppedw t h al o ad - t a p changer , t he r a t i o shoul d be determned f or each l o ad - t a p changer p o s i t i o n .b Faul t - gas anal ysi s . Theanal ysi s of t he per cent age of combust i bl e gases pr esent i n t he ni t r ogen capof seal ed, pr essur i zed o i l - f i l l e d t ransformrs can pr ovi de i nf or mat i on as t o t he l i kel i hood of i nc i p i e nt

f a u l t s i n t he t rans formr . Faul t - gas anal ysi s can be per f ormed onmnera l - oi l - i mmrsed t ransformrs ofal l s i z e s . When arc i ng or excessi ve heat i ng occurs be l ow t he t op sur f ace of t he o i l , some oi l de composesSomeof t he pr oduct s of t he decomposi t i on ar e combust i bl e gases t hat r i s e t o t he t op of t he oi l andmxw t h t he ni t r ogen above t he oi l . The t e s t s et f or t hi s t es t i s desi gned f or t he pur pose .Amal l sampl e ofni t r ogen i s removed f r omt he t ransformr and anal yzed .c I nsul ati ng- l i qui danal ysi s . I ns ul a t i ng- l i qui d ana l y s i s can be per f ormed i n t he f i e l d on oi l - i mmr se

power t r ans fo rmrs of al l s i z e s . Regul ar t e s t s , onasemannual b as i s , shoul d be madeon i nsul at i ng o i l sand askar el s . Sampl es shoul d betaken f r omt he equi pment andt e s t e d i n accordance w t h t hemanuf act urer ' s i n s t r u c t i o n s .2- 7 . Rot a t i ngmachinet est i ngThe t e s t s descr i bed be l owar e f or r o t a t i ng machi nes such as mot or s and generators . Theset e s t s ar eappl i ed based on t he hor sepower andWa t i n g of t he mac hi ne .2- 14


23/104

TM 5-694

a. Insulation-resistance (megger) testing. The insulation resistance test as described in paragraph 2-

4d is also applicable to rotating machines. This testing procedure applies to armature and rotating or

stationary field windings. If the insulation resistance is below the established minimum, circuit

components should be tested separately until the low insulation reading is located. Insulation-resistance

history based on tests conducted on new motors or after rewinding, cleaning, or from recorded data made

under uniform conditions form a very useful basis for interpretation of a machine winding condition.When comparing records of periodic tests any persistent downward trend is an indication of insulationtrouble even though the values might be higher than the recommended minimum safe values.

LIQUID LEVEL GUAGE

PRESSURE RELIEF

DEVICE

PRIMARY BUSHINGS

SECONDARY

BUSHINGS

PRESSURE/VACUUM

GUAGE

TANK LIFTING

LUGS

ARRESTER

MOUNTINGPROVISION

LIQUID TEMPERATURE

GUAGE

CORE AND COIL

BRACING

COILS

COOLING RADIATORS

DRAIN/FILTERING VALVE

BASE

Figure 2-4. Power transformer diagram

(Reprinted from Department of the Army TM 5-686. Power Transformer Maintenance and Acceptance

Testing 16 November 1998).

b. Dielectric-absorption testing. A dielectric absorption test for a rotating machine is performed as

described in paragraph 2-4e. A more complete and preferred test than the insulation resistance test, the

dielectric absorption test applies the voltage for 10 minutes or more to develop the dielectric-absorption

characteristic. The curve obtained by plotting insulation resistance against time gives a good indication

of moist or dirty windings. A steady rising curve is indicative of a clean, dry winding. A quicklyflattening curve is the result of leakage current through or over the surface of the winding and is

indicative of moist or dirty winding. If facilities are not available for a 10-minute test, a polarization

index test can be performed by taking readings at 30 and 60 seconds. The ratio of the 60-to-30-second

2-15


24/104

TM- 694or t he 10- t o- l - m nut e r a t i o wi l l serve as an i ndi cat i on of t hew ndi ng condi t i on . Tabl e 2- 2 l i s t srecommendedaccept abl e val ues .Tabl e2-2 Recommendedmnimumal ues ofpol ar i zat i on i ndexf or a l l machi ne component s i nsul at i oncl asses .

ThePol ar i zat i on I ndex t e s t i s not appl i cabl e t o noni nsul ated f i e l d w ndi ngs (See I EEE St d . 43- 2000Secti on 12. 2 . 1 ) .Note The number s i n t he t hermal c l a s s r a t i ng a r e t he hot - spot t emperat ures i n degrees cent i grade of t herotat i ngmachi ne I f t he 1mn i n s u l a t i o n r e s i s t a nc e i s above 5000 MS2, the cal cul ated P I . mayor maynobe an i ndi cat i on of i n s u l a t i o n condi t i on and i s therefore not recommendedas anasses sment t o o l .FromI EEESt d . 43- 2000 . Copyr i ght 000 I EEE Al l r i g h t s reserved .

c Over pot ent i al test i ng Overvol t age t e s t s ar e per f ormed duri ng nor mal mai nt enance operat i ons ora f t e r serv i c i ng or repai r of i mpor t ant machi nes or duri ng comm ssi oni ng . Such t e s t s , madeon al l or p a r t sof t he c i r c u i t t o group, ensure t h a t t he i nsul at i on l e v e l i s s u f f i c i e n t l y hi gh f o r cont i nued safe operat i on .Both ac anddo t e s t equi pment ar e avai l abl e Thet e s t overvol t ages t h a t shoul d be appl i ed wi l l depend ont he type of machi ne i nvol ved and l e v e l of r e l i a b i l i t y requi red f r omt he machi nes . However , i t shoul d beof s u f f i c i e n t magni t ude t o search out weaknes ses i n t he i nsul at i on that m ght cause f a i l u r e . St andard acover- pot ent i al t e s t vol t agewhennew s t w c e r a t e d vol t age pl us 1000 v o l t s ac . Thedo over pot ent i al t e s ti s per f ormedbyappl yi ngavol t age and measur i ng t he l eakage current . Thevol t age appl i ed duri ng t heaccept ance t e s t i s af unct i on of t he equi pment vol t age r a t i n g as shownby t he f ol l ow ngequat i on :

do acceptance t e s t vol t age i n kV=1. 6[ . 8( 2E+, 000) ] whereE s t he rated vol t age i nkVdomai nt enance t e s t vol t age i n kV=1. 6[ . 6( 2E+1 , 0 00 ) ] whereE s t he rated vol t age i n kVThese val ues f or t e s t vol tages are gi ven i nAS t i t c h i n Ti me, Manual onEl ect r i cal I nsul at i on Testi ngf ort he Pract i cal Man, Bi dd l e I nst r ument s, 1981 . Thestandard durat i on of t he t e s t i s bet ween 1 t o 5m nut esThedo acceptance t e s t vol t age i s appl i ed t o each w ndi ng separat el y w t h t he ot her w ndi ngs gr ounded .Thevol t age i s appl i ed i n s t e p s . F i r s t onet h i r d of t he do acceptance t e s t vol t age i s appl i ed . Leakagecurrent r eadi ngs ar e t aken at one mnute i n t e r v a l s upt o amaxi mumof t en m nut es. Thent he vol t age i si ncreased i n 1 kVi n t e r v a l s recordi ng t he l eakage current and appl i ed vol t age at each s t e p . Suf f i ci ent t i ms h a l l be al l owed bet ween s t eps for t he l eakage current to s t a b i l i z e . Thedata s h a l l be pl ot t ed l eakagecurrent versus appl i ed t e s t vol t age . The pl o t wi l l y i e l d asmoot h curve w t h a r i s i n g sl ope f or agoodi n s u l a t i o n system Anysudden changes i n t he curve c h a r a c t e r i s t i c s ar e an i ndi cat i on of i mpendi ngf a i l u r e . Ahi gh-pot ent i al t e s t madet o determnethe condi t i on of t he i nsul at i on up t o apredet erm nedvol t age l e v e l i s di f f i c ul t t o i n t e r p r e t . I t i s common pr a c t i c e t o compareknowngood r e s u l t s agai nst t e s tspeci mens t o determne what i s accept abl e andwhat f a i l s t he t e s t .2- 8 . Prot ec t i ve rel aysProtect i ve rel ays ar e used t o sense abnormal i t i es and cause t he t roubl e t o be i s o l a t e d w t hmnimumdi st urbance t o t he e l e c t r i c a l systemandt he l e a s t damaget o t he equi pment at f a u l t . Protect i ve rel aysshoul d be s e t andacceptance tested pri or t o bei ng pl aced i n serv i ce andte

commissioning of electrical system.pdf

Documents