Transformers Magazine, Vol. 2 No. 3, 2015.
Original scientific paper
Monitoring, diagnosis and fault finding on a power transformer
Michael Krüger
; OMICRON electronics
Udo Ranninger
; OMICRON electronics
Laurentiu Viorel Badicu
; OMICRON electronics
Abstract
An old transformer showed high concentrations of hydrogen and methane detected by the dissolved gas analysis which is usually performed at least annually as a routine test on bigger transformers. The utility decided to install a monitoring system for measuring gasses in the oil, partial discharges according to the IEC 60270 standard and additionally in the ultrahigh frequency range, capacitance and dielectric loss factor at 220 kV bushings, and for detecting transient over-voltages.
Different challenges were faced during design and installation of the diagnostic system and during the evaluation of the monitoring data. One year after installation, the monitoring system detected a strong increase of hydrogen and methane and also of partial discharges at 220 kV bushings. This initiated further diagnostic measurements. Partial discharges were detected and located. After opening the transformer the faults were identified. The damage was so serious that it was decided to scrap the transformer. This way the monitoring system could prevent a bigger damage in the substation.
Keywords
transformer; monitoring; condition diagnosis; dissolved gas analysis (DGA); partial discharge (PD) measurements; fault location; capacitance and dissipation factor monitoring
Hrčak ID:
182716
URI
Publication date:
8.7.2015.
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