page 1 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00 –DGA / DRM ON TAP-CHANGERSFOR ROUTINE TESTS
page 2 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00Scope of Tests defined in C57.12.00 (Tap Changers)
Section Test Tap-ChangerPositions Comment
Table 18 (Static) Resistance Measurement Min / N / Maxonly with first unit of newdesign
Table 18/8.3.1.
Ratio Test AllVariable supply voltage, noload
Table 18/8.3.2.
Impedance voltage andload-loss test
Min / N / Max Determination of uk, I0
8.3.2.1. Impedance testing Min / N / Max Which test setup ?
Table 18No-load lossesat 1.0 and 1.1 x UN
NDetermination of no-loadlosses, I0
Table 18 Operational testSequence
N–Min–Max–NVerification of mechanicaland electrical function
page 3 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00Scope of Tests defined in C57.12.00 (Tap Changers)
Section Test Tap-ChangerPositions Comment
Table 18 (Static) Resistance Measurement Min / N / Maxonly with first unit of newdesign; method has beenvoted out (Fall 2013)
Table 18/8.3.1.
Ratio Test AllVariable supply voltage, noload
Table 18/8.3.2.
Impedance voltage andload-loss test
Min / N / Max Determination of uk, I0
8.3.2.1. Impedance testing Min / N / Max Which test setup ?
Table 18No-load lossesat 1.0 and 1.1 x UN
NDetermination of no-loadlosses, I0
Table 18 Operational testSequence
N–Min–Max–NVerification of mechanicaland electrical function
page 4 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00Proposal for Additional Tests
(introduced by T.Ansari, J.Foldi, Fall 2013)
Transformer Test Pass criteria
De-energized One complete cycle of operationat 85% auxiliary supply voltage
§ All tap changes shall be completedsuccessfully with no signs of abnormalmotor sounds
Energized
No-load condition at nominalrated voltage (UN):One complete cycle of operation
§ Oil samples taken from the main tankbefore and after the test shall notindicate any dissolved gas increases§ Oil samples taken from the Diverter
compartment before and after the testshall not indicate any dissolved gasincreases for tap changers of thevacuum switching type§ Voltage on the open side and no-load
current I0 show uniform patternthroughout the range (step curve)§ Sound shall be uniform through all
switching operations
Transformer in Load Lossconnection with minimum 80%of the maximum nameplatecurrent IN in the regulatedwinding:One complete cycle of operation
page 5 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00Proposal for Additional Tests
Transformer Test Pass criteria
De-energized One complete cycle of operationat 85% auxiliary supply voltage
§ All tap changes shall be completedsuccessfully with no signs of abnormalmotor sounds
Energized
No-load condition at nominalrated voltage (UN):One complete cycle of operation
§ Oil samples taken from the main tankbefore and after the test shall notindicate any dissolved gas increases§ Oil samples taken from the Diverter
compartment before and after the testshall not indicate any dissolved gasincreases for tap changers of thevacuum switching type§ Voltage on the open side and no-load
current I0 show uniform patternthroughout the range (step curve)§ Sound shall be uniform through all
switching operations
Transformer in Load Lossconnection with minimum 80%of the maximum nameplatecurrent IN in the regulatedwinding:One complete cycle of operation
ðThese tests should be introduced to PC57.12.00 (Table 18) or Section 8.3
page 6 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00DGA on Tap Changers is not recommended for Routine Tests !
– During the test, the oil heats up and produces dissolved gases,due to heating and/or catalytic effectsð Gas patterns before and after the test(s) cannot be the same !
– DGA on Tap Changers is meaningful only for vacuum switching LTC typesð conventional arc-switching LTC types cannot be tested this wayð IEEE Standard is not generally applicable
– Limit values for DGA are type-specificð Different data sets, one for each tap-changer type/family/brandð Potential source for misinterpretation !
– Gas generation depends on application parametersð ”Normal” values vary with every applicationð Values which are normal for one type may indicate a fault for another type
page 7 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00Tap Changer Population – Big variety of types/models
ABB UZ
ReinhausenOILTAP® M
ReinhausenOILTAP® V
ReinhausenVACUTAP® VR
TransitionResistors
In-Tank TypeCompartment Type
ArcArc-Breaking-in-OilSwitching Technology
Switching TechnologyVacuum
Switching Technology
Reinhausen VACUTAP® RMV-II
TransitionReactance
page 8 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00DGA on Tap Changers
– Monitoring of LTC aging process– Detection of irregularities during LTC Life
When can it be helpful ?
– Trained personal for sampling, analysis, interpretation– Regular samplingð building up a history / trend analysis– Initial sample after commissioningð “Base line” data– Individual interpretation rules, depending on LTC model / brand / operational parameters
(see PC57.139)– Guidance by LTC manufacturer is recommended
What does it need ?
page 9 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00Winding Resistance Measurement
– In field service– Finding contact problems
When can it be helpful ?
Change-over selector problem Fine tap selector problem
Source: Hydro Quebec, CIGRE 2006 Publication A2-102
page 10 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00Dynamic Resistance Measurement (DRM)
– In field service / maintenance– Finding contact problems– Check of timing of tap selector AND diverter switch
When can it be helpful ?
– DRM equipment (different suppliers)– Initial sample after commissioningð Reference curve (individual fingerprint)– Trained personal for analysis and interpretation
! Different LTC types ð Different signals !– Guidance by LTC manufacturer is recommended
What does it need ?
page 11 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00Dynamic Resistance Measurement (DRM)
Resistor type LTC (on-site measurement, fault-free)
page 12 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00Dynamic Resistance Measurement (DRM)
Diverter switch Resistor type LTC
“Higher”
“Lower”
ðHigh sampling rate shows switching sequence of Diverter Switch
Source: Raka Levi, “Dynamic Resistance Measurement applied to On-Load Tap Changers”
page 13 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00Dynamic Resistance Measurement (DRM)
Reactance type LTC (on-site measurement, fault-free)
page 14 of 1403/11/2014IEEE C57.12.00 – DGA / DRM on Tap Changers for Routine Tests Rainer FrotscherI I I
IEEE C57.12.00Dynamic Resistance Measurement (DRM)
bridging to non-bridging non-bridging to bridging bridging to non-bridging
Startm
otordrive
Reactance type LTC (on-site measurement, fault-free)