Partial Discharge Measurements on 110kV Current Transformers. Case Study. Results

Abstract

The case study presents a series of partial discharge measurements, reflecting the state of insulation of 110kV instrument transformers located in Sibiu county substations. Measurements were performed based on electrical method, using MPD600: an acquisition and analysis toolkit for detecting, recording, and analyzing partial discharge, product of Mtronix Precision Measuring Instruments. MPD600 consists of three acquisition units (to separate, this way, the DP signal from electromagnetic disturbances, based on the three Phase Amplitude Relation Diagram – 3 PARD), an optical interface and a computer with dedicated software. The system allows measurements of partial discharge on site, even in presence of strong electromagnetic interferences because it provides synchronous acquisition from all measurement points. Measurements, with the ability to be calibrated, do render:  a value subject to interpretation according to IEC 61869-1:2007 + IEC 61869-2:2012 + IEC 61869-3:2011 and IEC 61869-5: 2011;  the possibility to determine the nature of the fault by identifying defective winding. Considering the results, the 110kV instrument transformer was directed to the repair shop and had the fault identified. The case study presents a series of partial discharge measurements, reflecting the state of insulation of 110kV instrument transformers located in Sibiu county substations. Measurements were performed based on electrical method, using MPD600: an acquisition and analysis toolkit for detecting, recording, and analyzing partial discharge, product of Mtronix Precision Measuring Instruments. MPD600 consists of three acquisition units (to separate, this way, the DP signal from electromagnetic disturbances, based on the three Phase Amplitude Relation Diagram – 3 PARD), an optical interface and a computer with dedicated software. The system allows measurements of partial discharge on site, even in presence of strong electromagnetic interferences because it provides synchronous acquisition from all measurement points. Measurements, with the ability to be calibrated, do render:  a value subject to interpretation according to IEC 61869-1:2007 + IEC 61869-2:2012 + IEC 61869-3:2011 and IEC 61869-5: 2011;  the possibility to determine the nature of the fault by identifying defective winding. Considering the results, the 110kV instrument transformer was directed to the repair shop and had the fault identified.