testing transf diff relays with single phase test currents - 03302015
TRANSCRIPT
7/23/2019 Testing Transf Diff Relays With Single Phase Test Currents - 03302015
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Methods for Testing
Transformer DierentialRelays Applied to Delta-Grounded Wye Transformers
Using Single-Phase TestCurrents
Tom rnstG Digital nergy
Craig Tal!otMinnesota Po"er
Te#as A$M Relay Conferen%e &'()
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Agenda
*ntrodu%tion Traditional +-phase testing method
Traditional (-phase testing method
Alternate (-phase testing methodAppli%ation e#amples
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*ntrodu%tion,
+-Phase testing %an !e %hallengingStraight for"ard magnitude $ phaseangles
Reuires . high-%urrent test set %hannels
(-phase testing
Reuires only & high-%urrent test set%hannels
Reuires non-o!/ious multipliers
Does not simulate real-"orld loading on
Delta-"ye transformers
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There is al"ays a "ay to do this
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*ntrodu%tion,
Alternate (-phase testing methodReuires only & high-%urrent test set%hannels
Simulates real-"orld (-phase loading%onditions
0o phase shifts
0o non-o!/ious multipliers
Suita!le for %ommission testing, tests thetransformer installation not the relaysettings
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Traditional +-phase testing,
Reuires simultaneous in1e%tion of test%urrents into a minimum of & relay"indings
Some test sets do not in%lude . high-%urrent %hannels
Magnitude relationship of the %urrents!ased on the transformer +-phase/oltage ratio
Slope %hara%teristi% tests
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Traditional +-phase testing,
Phase shift !et"een test %urrents %an!e %hallenging for delta 2 grd "yetransformers
3un%tion of the transformer internal ande#ternal %onne%tions, phases A4 5 $ C
might not !e on !ushings (4 & $ +Reuires thorough understanding of +-phase po"er
Same transformer %an !e +'6 lag or +'6lead
Slope %hara%teristi% tests
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Traditional +-phase testing,
Typi%aldelta - grd"ye
transformerandasso%iated+-phasetest%urrents
7+'6 lag8
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Traditional +-phase testing,
Typi%aldelta - grd"ye
transformer"ith rolledphasingandasso%iated+-phasetest
%urrents
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Traditional +-phase testing,
+-Phasetesting%onne%tion
s for a +'6lagtransformer
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Traditional (-phase testing,
Che%9s the fun%tionality of ea%h phase
:nly reuires & %urrent %hannelsMay reuire multipliers and phaseshifts that are not o!/ious 7Delta 2 GrdWye transformers8
Slope %hara%teristi% tests
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Traditional (-phase testing,
(-Phase
testing%onne%tions
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Somealternateideas are!etter than
others
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Alternate (-phase testing,
Conne%tions are related to thetransformer internal and e#ternal +-line diagrams
;ery ae%ti/e for %ommissioning
Simulates real-"orld load and short
%ir%uit %onditions0o non-o!/ious multipliers
0o non-o!/ious phase shifts
Slope %hara%teristi% tests
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Alternate (-phase testing,
Dierentially!alan%ed (-phase
through-%urrent for adelta - grd
"ye transf7+'6 lag8
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Alternate (-phase testing,
Dierentially!alan%ed (-phase test
%onne%tionsfor a delta -grd "ye
transf 7+'6lag8
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Alternate (-phase testing,
Dierentially!alan%ed (-phase
through-%urrent for adelta - grd
"ye transf7+'6 lead8
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Alternate (-phase testing,
Dierentially!alan%ed (-phase test
%onne%tionsfor a delta -grd "ye
transf 7+'6lead8
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Alternate (-phase testing,
Test %urrents %al%ulated !ased on0(<0& turns-ratio not /oltage ratio
=+ multiplier inherent
0o '-se >ltering multiplier reuired
Currents al"ays (?'6 apart
Test results %learly indi%ate ifdierential phase shift is set %orre%tly
Slope %hara%teristi% tests
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Alternate (-phase testing,
Dierentially !alan%ed through-%urrent
%ondition "ith %orre%t phase shift setting
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Alternate (-phase testing,
Dierentially !alan%ed through-%urrent
%ondition "ith in%orre%t phase shift
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Alternate (-phase testing,
Slope /eri>%ation "ith angle of "inding &
rolled until relay trips@ S '@(+<'@)'
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Alternate (-phase testing,
TestID
Winding 1(delta)connections
Winding 2 (wye)connections
A *n on A $ out on C AB *n on 5 $ out on A 5C *n on C $ out on 5 C
Test %onne%tions for a & "inding +'degree lag delta-"ye %onne%tion
transformer
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Alternate (-phase testing,
TestID
Winding 1(delta)connections
Winding 2 (wye)connections
A *n on A $ out on 5 AB *n on 5 $ out on C 5C *n on C $ out on A C
Test %onne%tions for a & "inding +'degree lead delta-"ye %onne%tion
transformer
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Wa9e up@ This is theinterestingpart
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Appli%ation #ample (, +'6ag
Transformernameplate
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Appli%ation #ample (, +'6ag
+-line
installationdiagram-dierentially
!alan%ed (-phase load
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Appli%ation #ample (, +'6ag
Test de>nitions
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Appli%ation #ample &, +'6ead
Transformer
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Appli%ation #ample &, +'6ead
+-line
installationdiagram-dierentially
!alan%ed (-phase load
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Appli%ation #ample &, +'6ead
Test de>nitions
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*n%orre%t :peration Analysis
Transformer dierential tripped one#ternal feeder fault
Caused !y "rong angle setting
Alternate method not used
0o load a/aila!le at time of %onstru%tionfor in-ser/i%e %he%9s
Using the alternate method mightha/e pre/ented the trip
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*n%orre%t :peration #ample
Wa/eform Capture
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Con%lusion,
Traditional +-phase testing method %an!e %hallenging
Traditional (-phase testing methoddoes not simulate real-"orld loading
Alternate (-phase testing methodsimulates real-"orld and tests the
settings against the installation
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