IEEE C57.12.00 – DGA / DRM ON TAP-CHANGERS FOR ROUTINE

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


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


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


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


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


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


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


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 ?


IEEE C57.12.00Winding Resistance Measurement

– In field service– Finding contact problems


Change-over selector problem Fine tap selector problem

Source: Hydro Quebec, CIGRE 2006 Publication A2-102


IEEE C57.12.00Dynamic Resistance Measurement (DRM)

– In field service / maintenance– Finding contact problems– Check of timing of tap selector AND diverter switch


– 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 ?



Resistor type LTC (on-site measurement, fault-free)



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”



Reactance type LTC (on-site measurement, fault-free)



bridging to non-bridging non-bridging to bridging bridging to non-bridging

Startm

otordrive

Reactance type LTC (on-site measurement, fault-free)

Documents

IEEE C57.12.00 – DGA / DRM ON TAP-CHANGERS FOR ROUTINE