Interpretation of partial discharges arising in medium voltage cable connections requires detailed knowledge of impedance values which represent substation components. A technique is presented that allows online impedance measurement in substations and ring main units (RMUs) without the need of switching. The measurement employs a Bulk Current Injection Probe (BCIP) clamped around a conductor inside the substation or RMU. The input impedance of the BCIP is measured using a pulse response measurement. Combining this impedance with a model of the BCIP yields the impedance of the RMU or substation at that location. The paper introduces the BCIP model and the calibration procedure to determine the model values The performance of the impedance measurements is verified using a test loop with different known impedances. The performance is checked with a measurement at an active RMU.
|Title of host publication||Proceedings of the 21st Nordic Insulution Symposium, Nord-IS 09, 15-17 June 2009, Gothenburg, Sweden|
|Place of Publication||Gothenburg|
|Publisher||Chalmers University of Technology|
|Publication status||Published - 2009|