hv field testing and ccvt re-verification december 2013
TRANSCRIPT
HV Field Testing and CCVT Re-verification
December 2013
© 2013 Quanta Technology LLC Page 2
CVT Calibration and Re-Verification Circuit
IED
Comparator
Fiber cable
Voltage measurement accuracy of 0.05% of amplitude and 0.05 degrees of phase.
4 V or 115V rated
69 V/ 115 V
CVT OVT
CVT Calibration
Control Room
Reference OVT
0.05% Class
OVT Electronics
Copper Cable
69 V/ 115 V
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CCVT or PT Calibration
CCVTs or PT under test
Ref. VTs connecting to HV line (live)
Electronic comparator (bridge)
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CCVT or PT Accuracy Re-verification Report
Test report provides:
1. Ratio Error and RCF
(Ratio Correction
Factor)
2. Phase Error, and
3. TCF (Transformer
Correction Factor)
for the CCVT under test at
the real operating voltage,
per IEEE Std. C57.13 and
C57.13.6.
Electronic Comparator (bridge) with < 0.05%
uncertainty traceable to NIST
Extract from Current/Voltage Sensors for Precise Measurements of Power Quality in
Distribution Systems for the Smart Grid
Eddy So and Farnoosh RahmatianNational Research Council Canada and Quanta Technology
IEEE PES General Meeting, Vancouver, BCJuly 23, 2013
© 2013 - Quanta Technology Canada ULC
Ease of Installation and Use• Safety• Light weight• Easy to connect to HV line
– High-impedance– Isolation
• Integrated data processing• Rugged design (environmental elements)
© 2013 - Quanta Technology Canada ULC
Traceability• Unbroken chain of measurements• Compliance with regulations and standards• On site calibration / verification of sensors
– The accuracy requirements of the reference system– Uncertainty < 1/4 devices being verified in the field
• Documentation
© 2013 - Quanta Technology Canada ULC
Calibration and Traceability• Traceability
– Unbroken Chain of Measurements Tracing Back to National and/or International Standards (e.g., NIST)
– Uncertainty analysis and certification
International Standard
National Standard – National Labs, e.g., NIST, NRC
Regional or Portable References
Device Under Test
DUT 1 DUT 2 DUT n
Ref. A Ref. B
NIST Reference Std
DUT 3
Ref. C
NRC Reference Std
International Reference Std
Example:
0.2 – 1.0%
200-1000 ppm
20-50 ppm
DUT 4
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Calibration Circuit for OVT (OPT)
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Calibration Results for OVT (OPT)Ratio Error
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Calibration Results for OVT (or OPT)Phase Error
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Live-line Connections of OVT• Advantage OVT
– Excitation Current about 1 mA regardless of rated voltage, as compared to conventional PT excitation current of about 100 mA to 1 A (depending on rated voltage).
• Can be connected live
© 2013 - Quanta Technology Canada ULC
OVT Qualification Conclusion• NRC (NIST) Test Results indicate the suitability
of OVT to be used as reference Instrument Transformers for live-line on-site calibrations of HV Revenue Metering Systems of accuracy class 0.2 – 0.3, including HV PMU Systems which usually are of accuracy class 0.5 – 1.0.
• Because of its linearity, certain accuracy and performance parameters can be extended over harmonics and frequency
© 2013 - Quanta Technology Canada ULC