The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Under the general backgrounds of fast development of economy, Chinapsila power industry is undergoing a new upsurge of infrastructure construction. With the urgent need of the whole society for reliable power supply, condition based Maintenance strategy is becoming the mainstream of the operation and management of the power system. In this paper, recent progress of condition monitoring and diagnostic...
Partial discharge (PD) measurements performed online can provide important information regarding insulation system reliability. However, PD detectors suitable for online measurements (or monitoring) should be endowed at least with tools that are able to deal with noise and multiple PD sources. PD source identification tools that can exploit data streams from other sensors are, moreover, very important...
In this paper, recent progress in condition-monitoring and diagnostic techniques for power equipment in Japan is reviewed and discussed with a future technical perspective. In particular, the dissolved gas-in-oil analysis (DGA) technique for power transformers and the UHF partial discharge detection technique for gas insulated systems are introduced in order to both enhance measurement reliability...
Recent R&D progress on condition monitoring and diagnosis for power apparatus such as substation equipments including GIS and main transformer, rotating machineries including hydro-generator, turbo-generator, and HV motor, and power distribution equipments including power cable, overhead line system and lightning arrester, and so on in Korea are investigated in this paper. The fields experiences...
This paper represents the VHF/UHFpartial discharge measurement technique compared with conventional partial discharge measurement method, IEC 60270. The artificial partial discharge objects which represent corona discharge, internal discharge, and surface discharge, were set up and tested with the mention techniques. The test results show that three kinds of partial discharge give obviously different...
The diagnostic examination of partial discharges (PD) for the condition assessment of insulating systems of high voltage (HV) equipment, formerly carried out mostly in test bays to control new products after the manufacturing process, has reached currently numerous on-site/on-line applications as well as being used for the permanent monitoring of HV equipment with e.g. strategic importance. Basic...
A method based on frequency characteristics to distinguish partial discharge (PD) source in oil filled transformer is proposed. Frequency spectrum of electromagnetic wave from two typical PD sources, i.e., protrusion of metal and air void in oil was investigated. It was found that metal protrusion gave PD signal with stronger component in the frequency range above several hundreds MHz compared with...
A metallic particle appeared in a gas insulated switchgear (GIS) sometimes adheres on a solid spacer surface. If the adhered metallic particle is exposed to a surge high voltage, a breakdown (BD) may be induced. Therefore, it is eagerly demanded to diagnose its risk correctly under the service voltage by partial discharge (PD) measurement. In this paper, particle-initiated surface PD characteristics...
Impulse damage may occur to insulators within electrical systems due to lightning strikes, switching operations or self-clearing flashovers. This damage may not result in immediate failure of the system; however, progressive degradation can occur due to repeated events. If it is possible to develop economical systems to monitor the effects of impulse degradation of solid insulation, it may be possible...
This paper presents results of PD test at elevated frequency of supply. Particular attention was given to the discharges that occur in moist pressboard layers immersed in transformer oil. The effect of moisture content on the PD activity was investigated based on the observation of the PD quantities and the characteristics of the PD distributions. Data obtained from the PD test is presented in phase-resolved...
Appearance of electrical discharges in high voltage apparatuses with reasonable magnitude and frequency can be interpreted as abnormal condition. The discharge may take place in several types. Firstly, corona discharges which represents abnormal electric stress on a conductor. Secondly, void discharge which represents discharge take place in a gas filled void in solid or liquid insulation. Thirdly,...
We have designed and manufactured four types of typical defects found in power transformers to simulate partial discharge (PD) in oil insulated power transformers. Stable PD signals were generated by applying AC voltages on to the PD cells. We measured spectral response of PD signals from these defects using our Ultra-high frequency (UHF) PD measuring system and apparent discharge using IEC60270 PD...
Experiments of partial discharge (PD) current pulse and phase resolved PD characteristics were performed using various artificial defects in oil/pressboard composite insulation system in oil-filled transformer. As artificial defects, we used barrier insulation model-in-oil, oil wedge model, air void model, floating electrode model, and oil gap model. As a result, it was found that the rise time, fall...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.