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This paper describes and compares different de-noising approaches for partial discharge (PD) measurements. The working principles of antenna gating, dynamic noise gating, real-time pulse waveform analysis and synchronous multiterminal PD measurements will be described briefly. Hints will be given which method is most suitable for different measurement situations and noise conditions. This also covers...
Power transformers are important nodes in the electrical power grid. Common reasons for breakdown are problems in the insulation system. Detecting partial discharge in the insulation system of a power transformer at an early stage reduces the risk of total breakdown of power apparatus. One method to detect partial discharge is the acoustic measurement. With this technique a detection and localization...
Partial Discharge (PD) measurements are considered as a powerful technique for testing and monitoring the condition of high-voltage (HV) insulations. PD diagnostics is generally accepted as an early breakdown indicator, which is also reflected in numerous standards. In the present contribution, the authors describe the fundamentally different propagation mechanisms of electrical impulses in the conventional...
Partial Discharge (PD) measurements are considered as a very powerful technique for testing and monitoring the condition of high-voltage (HV) insulations. PD activity is generally accepted as an early breakdown indicator, which is also reflected in numerous standards. In the present contribution, the authors describe the fundamentally different propagation mechanisms of electrical impulses in the...
The reliability of electrical systems depends on the quality and availability of the power apparatus. Power transformers are important nodes in the electrical power grid. Common reasons for breakdown are problems in the insulation system. Detecting partial discharge in the insulation system of a power transformer at an early stage reduces the risk of total breakdown of power apparatus. One method...
For PD measurements in unscreened laboratories, factory environments, or even during on-site conditions, the measuring result is overlaid and sometimes dominated by numerous disturbances. As common-wave interferences such as radio signals, e.g., can easily be suppressed by frequency-domain filters, pulse-like disturbances cannot be eliminated by filters due to their broad-banded frequency spectrum...
On-side PD measurements are very often interfered by external disturbances as corona from neighboring systems and switching activity from the grid, respectively. Therefore no clear assignment of PD sources to the object is possible. However, a substantiated risk assessment requires such assignment and, even more, an identification and location of the PD fault. As the classical PD measurement methods,...
Power transformers are critical, capital-intensive assets for utilities and industry. Transformers are extremely reliable; however, many of the transformers in use today have already exceeded their design life. Today transformers are not automatically replaced, if they have reached the end of their life span, but left in service as long as possible. In contradiction to the past power transformers...
This paper shows the benefits of synchronous multichannel PD measurements. Different methods of evaluation as 3PARD, 3PTRD and 3CFRD are presented in theory and by application examples. These advanced evaluation techniques require a fully synchronized multi-channel PD measuring system for advanced PD data evaluation. PD source separation and the separation of PD and interferences can simplify the...
With four case studies (dry-type transformer, power transformer, GIS, generator) this paper describes the principle of synchronous multi-channel PD measurements and its benefits for PD data evaluation. With respect to monitoring the tracing of a charge value as QIEC over the measuring time is not sufficient to assess the PD activity of an HV apparatus. With state-of-the-art PD evaluation techniques...
Frequency response analysis (FRA) is a powerful and sensitive tool to assess the mechanical and geometrical integrity of core, windings and clamping structures within power transformers, by measuring their transfer functions over a wide frequency range. Despite a rapidly increasing number of users throughout the world and a significantly growth of knowledge about the application of the method, the...
With the advancing age of power transformers, a regular check of the operating conditions becomes more and more important. The Dissolved Gas Analysis (DGA) is a proven and meaningful method such that if increased proportions of H2 and hydrocarbon gases are found in the oil, the fault must be located as soon as possible. In order to find out the reason for high gas values, further tests have to be...
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