Abstract-This paper introduces a new advanced partial discharge detection system for detecting partial discharge activity in the accessories of power cables during the acceptance test. The system consists of three autonomous PD measuring systems which communicate via a wireless communication network with one main computer. As a result, the measured data of each measuring unit can be displayed and analyzed at one single point near e.g. the voltage source which makes easy communication between the measuring technician and test engineer possible.Based on several field measurements performed in Europe on different 380kV and 150kV cables systems aspects of measurement and data processing are discussed.
The UHF partial discharge measurement technique is under research in order to be used for the detection, identification and localization of discharging defects within a power transformer. However, it requires installed dielectric windows on the transformer tank for the placement of the UHF sensors, a feature not available in all transformers especially old ones that have a higher risk of failure. Therefore, it is necessary to develop UHF sensors that can be used in the case of transformers without dielectric windows. In this paper such a sensor in its early design stages is studied, which can be inserted in a transformer from one of its valves.
Different diagnostic techniques are currently available for on-line insulation condition assessment of power transformers. Amongst these techniques a relatively new technique for detecting partial discharges (PD) in the Ultra High Frequency range of the spectrum is also introduced. The UHF technique has been recently presented in the field of transformer diagnostics, and although it is under development it shows great potential for on-line detection, recognition and location of PD activity.This paper describes the practical application of the UHF technique on two new identical 90 MVA, 150 kV power transformers. Both transformers are equipped with four external UHF sensors. Initially, injection measurements were performed to investigate the effects experienced by UHF signals when propagating through the transformer. Moreover, software developed to model the propagation of UHF signals inside the transformer tank was tested in its application to these specific transformers.The results obtained during the both the induced voltage test, as well as during the PD acceptance test in the factory are described. The practical experiences related in this paper provide further insight into the application of UHF PD monitoring techniques to power transformers.
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