PD measurement is a worldwide-accepted method for insulation diagnosis and a required part of the acceptance testing for many HV assets. To facilitate PD measurements different techniques/methods have been developed and they are in use for laboratory and on-site applications. All these methods can be divided into conventional and unconventional PD measuring methods. The latter are the subject of this guide.@en

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.@en

In this paper measuring results of partial discharges in power cable accessories are described. For the purpose of measuring simultaneously partial discharge activity in three or more accessories during an acceptance test, a wireless partial discharge detection system was developed. Therefore, each power cable accessory is equipped with either an internal or external sensor to decouple the partial discharge signals. The system uses narrow-band detection and is described in this paper. The computers controlling the measuring units are connected via a wireless network which allows communication between the different units and the main computer situated at the voltage source site. Moreover, effective real time noise-suppression is possible by tuning the system to a noise-free frequency band. Practical examples of this system are shown based on several measurements performed in the field.@en

The VHF/UHF PD detection technique is a non-intrusive method for power cable PD diagnostics. It incorporates a VHF/UHF current probe placed at the grounding of the cable and a spectrum analyzer connected to the probe. This technique however is very difficult to calibrate due to different factors affecting the frequency response of the measuring setup. In this paper the calibration procedure is described and discussed. Furthermore two examples of on-site calibration are presented, before the actual PD measurements take place. In these examples the sensitivity of the technique is also studied.@en

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.@en

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.@en

This paper describes the first results from experimental investigations which have been carried out to study the partial discharge phenomena in power transformer insulation. Using different types of modeled insulation defects and ageing tests it is aimed to organize a database of known defects, which will be used for recognition of discharges of unknown sources of defects. Moreover, the first results of the investigation of degradation processes of pressboard during ageing are described. The experiments were carried out using the classical IEC 60270 method and the UHF method. Phase resolved patterns of the defects were collected for statistical analysis. Different defects were discriminated using cluster analysis.@en