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Condition Based Assessment/Condition Based Assessment/
Aradhana Ray,Aradhana Ray, Charles SweetserCharles Sweetser
OMICRON, IndiaOMICRON, India OMICRON, USAOMICRON, USA
© OMICRON 24. November 2009 Page: 1
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A endaA enda• Sweep Frequency Response Analysis (SFRA)
• Advanced Diagnostic Measurements on Power
• u n y n
• ar a sc arge easuremen s
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Advanced Dia nosticsAdvanced Dia nostics• Field use and recognition is becoming
, ,
modern instrumentation
• Extension of Standard Tests that add value
• PF/TD, Tip-Up, Variable Frequencies
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Transformer Test Cate oriesTransformer Test Cate ories
•
• Thermal
• M h ni l
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Transformer TestsTransformer TestsDielectric Thermal Mechanical
DGA DGA SFRAOil Screen Oil Screen Leakage Reactance
Exciting Ima DC Winding RES Exciting Ima
TTR DC Winding RES
Partial Discharge
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SSFRA DiagnosticsFRA Diagnostics
Aradhana Ray,Aradhana Ray, Charles SweetserCharles Sweetser
OMICRON, IndiaOMICRON, India OMICRON, USAOMICRON, USA
© OMICRON 24. November 2009 Page: 6
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What is SFRA?What is SFRA?
Powerful and sensitive tool to assess themechanical and electrical inte rit of owertransformers active part
Measurement of the transfer function over awide frequency range
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Transformer Test Cate oriesTransformer Test Cate ories
•
• Thermal
• “M h ni l ”
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Transformer TestsTransformer TestsDielectric Thermal Mechanical
DGA DGA SFRAOil Screen Oil Screen Leakage Reactance
Exciting Ima DC Winding RES Exciting Ima
TTR DC Winding RES
Partial Discharge
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Dia nostic NoteDia nostic Note• Tests should be art of a
protocol
• supporting evidence.
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Transformer TestsTransformer TestsDielectric Thermal Mechanical
DGA DGA SFRAOil Screen Oil Screen Leakage Reactance
Exciting Ima DC Winding RES Exciting Ima
TTR DC Winding RES
Partial Discharge
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When to use SFRA?When to use SFRA? quality check during manufacturing
proof the transformer after short circuit testing
check the integrity of transformers after transport
routine dia nostic measurement
condition assessment after the occurrence of high transient
fault currents
diagnosis after transformer alarm or protection tripping
. .
combustible gases)
further ins ection after the observation of unusual routine test
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results
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WhenWhen to use FRA?to use FRA?e very ort
•Quality Assuring•Transport CheckingTruck Transport 1
T
r af
•After Short Circuit Test
•Failure InvestigationShip Transport
•Routine Measurement
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•Transport Checking
•Failure Investigation (DGA)
Truck Transport 2
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Which problems can be detected?Which problems can be detected?
Winding deformation axial&radialuc ng, ng… , par a w n ng co apse
Displacement between high and low voltagewindings
Shorted or o en turns
Faulty grounding of core or screens
Core movement and / or shorted laminates
Broken or o en internal connections
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Radial FailureRadial Failure
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Axial FailureAxial Failure
5 000 +001 1 000 +002 5 000 +002 1 000 +003 5 000 +003 1 000 +004 5 000 +004 1 000 +005 5 000 +005 1 000 +00 5 000 +00f/Hz
. + . + . + . + 3 . + 3 . + . + . + . + . + . +
-25
-20
-15
-10
-40
-35
-30
dB
-50
-45
100
150
1V 1U 1W 1V
f/Hz5. 000e+001 1. 000e+002 5 .000e+002 1 .000e+003 5 .000e+003 1 .000e+004 5 .000e+004 1 . 000e+005 5 .000e+005 1. 000e+006 5 . 000e+006
°
-100
-50
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Conductor TiltingConductor Tilting
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Core FaultsCore Faults
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??????????????
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SFRA Measuring MethodSFRA Measuring Method
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The SFRAThe SFRA Measurement PrincipleMeasurement Principle
Transformator
0
1
2
3
0 50 100ung U1/U1 in V/V
0
1
2
3
0 50 100ung U2/U1 in V/V
Erregungssignal(variable Frequenz)
Antwortsignal
-3
-2
-1
Zeit t in µs
Spann
3
-3
-2
-1
Zeit t in µs
Spann
Input signal Output signal
-
-1
0
1
2
0 50 100
Span
nung U/U1 in V/V
U2^U1^
1-|TF(f1)|
U2^| |
ϕ(f1)/2πf
variable frequency)
1.0
1500
200.0
Betragsfunktion|TFU2/U1(f)|
Phasenfunktionarc(TFU2/U1(f))
-3
-
Zeit t in µs
U1^| |
=ϕ
f/Hz1.000e+002 1.000e+003 1.000e+004 1.000e+005
dB
-10
°
150
PhaseMagnitude
0.2
0.4
0.6
0.8
|TFU2/U1(f)| in V/V|
-150.0
-100.0
-50.0
0.0
50.0
100.0
.
arc(TFU2/U1(f)) in deg
-70
-60
-50
-40
-30
-20
f/Hz1.000e+002 1.000e+003 1.000e+004 1.000e+005
-150
-100
-50
0
50
100
© OMICRON Page: 2224/11/2009
0.0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
f in MHz
-200.0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
f in MHzN V
-90
-80
N V
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TheoreticalTheoretical BackgroundBackground
400
500
600
700
800
900
U (V)
transformer
-0.20
0.00
0.20
0.40
0.60
0.80
I (A)
0
100
200
300
0.0 20.0 40.0 60.0 80.0 100.0
Zeit (µs)
complex RLCM-Network -0.80
-0.60
-0.40
0.0 20.0 40.0 60.0 80.0 100.0
Zeit (µs)
input signal response signal
filtering, sampling, windowing, FFT, quotient
2.5
2 0
3.0transfer function (magnitude) transfer function (phase)
0.5
1.0
1.5
.
|TF(f)|
-2.0
-1.0
0.0
1.0
.
arc(TF(f))
© OMICRON Page: 2324/11/2009
.
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Frequenz f
MHz
- .
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Frequenz f
MHz
frequency f frequency f
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TheoreticalTheoretical BackgroundBackground
Measurement Measurement
Cables Grounding
t X t x ω sin)( =
ca e ca e
CMC CMC
RMC12 RMC34
specimenm
m
Z R
R
sU
sU TF +
==)(
)(
1
2
CMC CMC
Complex RLC Network )/ (log20 1210 U U k =
U1 50Ω U2 50Ω
50Ω
)/ (tan 12 U U ∠∠=−ϕ
/1 .0 00e +0 02 1. 000 e+ 00 3 1 .0 00 e+ 004 1. 000 e+ 00 5 1 .0 00 e+ 006
dB
0
10
°
150Magnitude (k) Phase
H1 H2 H2 H3 H3 H1
/ z
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
f/Hz1.000e+002 1.000e+003 1.000e+004 1.000e+005 1.000e+006
-200
-150
-100
-50
0
50
100
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Swept Frequency Response Analysis (SFRA)Swept Frequency Response Analysis (SFRA)
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SFRA Princi leSFRA Princi le
C = ε * A/d
© OMICRON Page: 2524/11/2009
The transformer as a RLC networkThe transformer as a RLC network
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SFRA RLC BasicsSFRA RLC Basics
sLR
R
sU
sU TF
m
m
i
o
+==
)(
)(
0
1)(
)(
+==
sC R
sC R
sU
sU TF
m
m
i
o
0
101
102
103
104
105
106
107
-150
-100
-50
Frequency (Hz)
Amplitude [dB]
L=200 mH
L=2 mH
L=20 H
101
102
103
104
105
106
107
-200
-150
-100
-50
Frequency (Hz)
Amplitude [dB]
C=1uF
C=20nF
C=1pF
-100
-50
0
Phase [°]
L=200 mH
L=2 mH
L=20 H
0
50
100
Phase [°]
C=1uF
C=20nF
C=1pF
© OMICRON Page: 2624/11/2009
10 10 10 10 10 10 10
Frequency (Hz)
10 10 10 10 10 10 10
Frequency (Hz)
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RLS BasicsRLS Basics• Parallel RLC - VALLEY
• Series RLC PEAK
• 0 dB = 0 Ohms = Short
• -100 dB = ∞ = Open
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T ical ResultsT ical Resultsf/Hz
5.000e+001 1.000e+002 5.000e+002 1.000e+003 5.000e+003 1.000e+004 5.000e+004 1.000e+005 5.000e+005 1.000e+006
-20
-40
-30
-60
-50
dB
-70
100
150
N W sec N V sec N U
f/Hz5.000e+001 1.000e+002 5.000e+002 1.000e+003 5.000e+003 1.000e+004 5.000e+004 1.000e+005 5.000e+005 1.000e+006
°
-100
-50
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Measurement T esMeasurement T es
• Open Circuit - Exciting Ima
• or rcu - ea age eac
• Interwinding - CAP
© OMICRON
• rans er o age -
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MeasurementMeasurement SetupSetup
Open Circuit
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HVHV vs. LVvs. LV Winding ResponsesWinding Responses
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O en Circuit TestsO en Circuit Tests
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MeasurementMeasurement SetupSetup
Short Circuit Test
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O en vs. shorted testsO en vs. shorted tests
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Short Circuit TestsShort Circuit Tests
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MeasurementMeasurement SetupSetup
n er-w n ng measuremen s: apac ve e n uc ve r g
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CapacitiveCapacitive InterInter--Winding TestWinding Test
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InductiveInductive InterInter--Windin TestWindin Test
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Usable Fre uenc Ran esUsable Fre uenc Ran es
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TheThe General Curve StructureGeneral Curve Structure
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Anal sis Strate iesAnal sis Strate ies
• Baseline
• m ar n
• Phase Comparison
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7. SFRA Inter retation7. SFRA Inter retation
arison
arison
U V W U V W
Date XDate Y
sed c
om
sed c
om
f/Hz1 . 00 0 e +0 0 2 5 . 0 00 e +0 0 2 1 . 0 00 e +0 0 3 5 . 00 0 e+ 0 0 3 1 . 0 00 e +0 0 4 5 . 0 00 e + 00 4 1 . 0 00 e +0 0 5 5 . 0 00 e +0 0 5 1 . 0 00 e +0 0 6
-10
f/Hz1 . 00 0e + 00 2 5 . 00 0 e+ 0 02 1 . 00 0e + 00 3 5 . 00 0e + 00 3 1 . 00 0e +0 0 4 5 . 00 0 e+ 00 4 1 . 00 0 e+ 0 05 5 . 00 0e +0 0 5 1 . 00 0e + 00 6
20
-10
f/Hz1 . 0 00 e +0 0 2 5 . 0 00 e + 00 2 1 . 0 00 e +0 0 3 5 . 0 00 e +0 0 3 1 . 00 0 e +0 0 4 5 . 0 00 e +0 0 4 1 . 00 0 e +0 0 5 5 . 00 0 e +0 0 5 1 . 00 0 e+ 0 06
-20
-10
Trafo A Trafo A
Fingerprint Failure investigationTime b
Failure investigation
Inte rit verificationP
hase b
dB
-80
-70
-60
-50
-40
-30
-20
dB
-80
-70
-60
-50
-40
-30
-20
dB
-80
-70
-60
-50
-40
-30
f/Hz1 .0 0 0 e+ 0 0 2 5 .0 0 0 e+ 0 0 2 1 .0 0 0e + 0 0 3 5 .0 0 0 e+ 0 0 3 1 .0 0 0 e+ 0 0 4 5 .0 0 0 e+ 0 0 4 1 .0 0 0 e+ 0 0 5 5 .0 0 0e + 0 0 5 1 .0 0 0 e+ 0 0 6
dB
-80
-70
-60
-50
-40
-30
-20
-10
U vs. V
U V WU V W
Construction based comparison
Trafo ATrafo B
f/Hz1 . 00 0 e +0 0 2 5 . 0 00 e +0 0 2 1 . 00 0 e +0 0 3 5 . 00 0 e+ 0 03 1 . 0 00 e +0 0 4 5 . 00 0 e+ 0 0 4 1 . 0 00 e +0 0 5 5 . 0 00 e +0 0 5 1 . 0 00 e +0 0 6
-30
-20
-10
f/Hz1 . 00 0e + 00 2 5 . 00 0 e+ 0 02 1 . 00 0 e+ 00 3 5 . 00 0e + 00 3 1 . 00 0e +0 0 4 5 . 00 0 e+ 00 4 1 . 00 0e +0 0 5 5 . 00 0e + 00 5 1 . 00 0e + 00 6
-40
-30
-20
-10
© OMICRON Page: 4224/11/2009
dB
-80
-70
-60
-50
-40
dB
-80
-70
-60
-50
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SFRA & Transformer Trans ortationSFRA & Transformer Trans ortation
transportation.
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Transportation is not allways easyTransportation is not allways easy
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First indication of transport damageFirst indication of transport damage
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SFRASFRA -- ResultsResults
Suspect unitSuspect unit Sister transformerSister transformer
--
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Af i h fAf i h f
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After opening the transformerAfter opening the transformer
Bent clamping rod,Bent clamping rod,Ruptured clampingRuptured clamping
© OMICRON Page: 4724/11/2009
to the rightto the right
ramerame
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Possible Testing IssuesPossible Testing Issues
• Oil• Residual Magnetization
© OMICRON
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Influence of the insulatin oilInfluence of the insulatin oil
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ue: t - reen: t out
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Com arison: with / without TankCom arison: with / without Tank
f/Hz5 .0 00 e+ 00 1 1 .0 00 e+ 00 2 5 .0 00 e+ 00 2 1 .0 00 e+ 00 3 5 .0 00 e+ 00 3 1 .0 00 e+ 00 4 5 .0 00 e+ 00 4 1 .0 00 e+ 00 5 5 .0 00 e+ 00 5 1 .0 00 e+ 00 6
1
f/Hz1. 000e+006 2. 000e+006 3. 000e+006 4. 000e+006 5. 000e+006 6. 000e+006 7. 000e+006 8. 000e +006 9. 000e+006
1
-30
-20
-10
-30
-20
-10
-60
-50
-40
-60
-50
-40
dB
-70
100
150
dB
-70
100
150
U V U V (1)
f/Hz5 .0 00 e+ 00 1 1 .0 00 e+ 00 2 5 .0 00 e+ 00 2 1 .0 00 e+ 00 3 5 .0 00 e+ 00 3 1 .0 00 e+ 00 4 5 .0 00 e+ 00 4 1 .0 00 e+ 00 5 5 .0 00 e+ 00 5 1 .0 00 e+ 00 6
°
-100
-50
U V U V (1)
f/Hz1. 000e+006 2. 000e+006 3. 000e+006 4. 000e+006 5. 000e+006 6. 000e+006 7. 000e+006 8. 000e +006 9. 000e+006
°
-100
-50
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StandardisationStandardisation in the Worldin the World
DL 911/2004DL 911/2004PC57.149/D5PC57.149/D5WG A2.26WG A2.26
CHINA
© OMICRON Page: 5124/11/2009
IEC S d d 60076IEC S d d 60076 1818
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IEC Standard 60076IEC Standard 60076--1818
© OMICRON Page: 5224. November 2009
T t C tiT t C ti
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Test ConnectionsTest Connections
© OMICRON
Test Recommendations (IEEE)Test Recommendations (IEEE)
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Test Recommendations (IEEE)Test Recommendations (IEEE)
•
• DETC as Found
• Open Circuit Test
• Short Circuit Test
© OMICRON
RadialRadial Deformation (IEEE)Deformation (IEEE)
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RadialRadial Deformation (IEEE)Deformation (IEEE)
© OMICRON
Axial DeformationAxial Deformation
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Axial DeformationAxial Deformation
© OMICRON
Core DefectsCore Defects
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Core DefectsCore Defects
© OMICRON
TurnTurn toto Turn ShortTurn Short
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TurnTurn--toto--Turn ShortTurn Short
© OMICRON
Open WindingOpen Winding
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