Search results for "Partial discharge"
showing 10 items of 70 documents
Time Evolution of Partial Discharges in a Dielectric Subjected to the DC Periodic Voltage
2022
Partial discharge (PD) detection can be considered one of the most useful tools for assessing the insulation conditions of the power apparatus in high-voltage systems. Under AC conditions, this analysis is widely employed in online and offline tests, such as type tests or commissioning, and can be carried out by applying the phase-resolved PD (PRPD) method, since the patterns can give information about the defect classification. Under DC voltages, the classic pattern recognition method cannot be performed, and the measurements show complexities related to the nature of the phenomena. For this reason, to date, a standard for PD measurements under DC does not exist. In previous papers, a new …
Electrical Aging Tests on Enameled Wire Exposed to Gamma Irradiation
2011
Electromagnetic radiated field measurements for partial discharge diagnostic
2004
Recently, improvements have been made in the diagnostic of electrical insulation systems by means of electric Partial Discharge (PD) standard measurements through a stochastic approach in the treatment of the acquired data: in this way, the identification of the defects as well as the separation of multiple defects simultaneously active, have been successfully performed. However, the standard PD measurement process can be affected by the well-known parasitic effects due to conducted noise whose spectrum can have characteristics similar to those of the measured signal. Moreover, the classic PD measurement system have to be suitable assembled on the Device Under Test (DUT) so determining a co…
Partial Discharge on-line measures in cable's EPR insulation
2004
In this paper, an experimental study, carried out on an operating MV cable, is presented. The aim is to identify, locate and characterize defects in the cable's EPR (ethylene-propylene copolymer rubber) insulation. Direct partial discharge measurements have been compared to those obtained by high frequency electromagnetic field measures. The latter have been carried out using a sensor which does not require any galvanic connection with the system under test and that performs an intrinsic localization of the defect. Moreover, an analysis of an MV cable junction has been carried out using the same tools.
Overcoming synchronization issues in wireless technology Partial Discharge measurement
2016
In this paper, several aspects of the fundamentals of wireless Partial Discharge (PD) measurements are first discussed. Then, the relevance of the problem of voltage synchronization in PD wireless diagnosis is outlined. When portable instruments are used for PD detection, the main issue is the voltage measurement at the site where the PD detection is carried out. When such analysis is carried out over shielded cables, the AC (50/60 Hz) voltage reference signal is not easily detectable, while one of the basic parameters for PD diagnosis, the displacement of the inception voltage of the PD as compared to the reference voltage, is not available. Even if highperformance sensors are readily avai…
A portable instrument for the location and identification of defects generating PD
2011
A portable instrument based on an antenna probe and suitable for partial discharge detection, have been characterized through both laboratory and on-site experiments carried out on coils and stator windings of ac rotating machines. The antenna probe allows the capture of electromagnetic waves in a bandwidth of 0.1–100 MHz. Pulse signals and ac supply voltage reference are obtained by means of high-pass and low-pass filters, respectively, so avoiding the need of a direct connection with the objects under test. By this way, real-time phase resolved partial discharge patterns can be derived. Results of a comparison of the diagnostic information provided by PD patterns due to conducted and irra…
Performance of the Shape of Partial Discharge Signal Wireless Probes
2013
This paper focuses on the evaluation of the performances of three different antenna sensors suitable of Partial Discharge (PD) measurements. Monopole, triangular and spherical antennas were simulated by means of the surface moment method. The transmitting system is modeled by a power electronic device with a fault current between two metal plate. The shape of the simulated transmitted and received signals have been compared to verify the sensor the provides the best fidelity among the three. The auto-correlation function and the Pearson correlation index are adopted here for the comparison. A discussion on the dynamic characteristic of the different antenna probes and their use in different…
A two-end traveling wave fault location system for MV cables based on LoRa technology
2017
In this paper a new low cost device is proposed for fault location in power distribution system. The device is part of a system that should include several units installed in couples at the two ends of MV cable lines. Their low cost justifies a widespread installation of these devices, moreover other functionalities could be considered so as to enrich the potential of the system for MV cables monitoring and asset management. The system exploits a two-end traveling wave technique, low complexity and low cost solutions both for the analog front end as well as for the communication infrastructure. A LoRa network is indeed considered as wireless modulation technique perfectly suited when commun…
A computer‐aided instrument for pattern recognition of partial discharges
1998
In this paper a new computer‐aided digital system for partial discharge (PD) measurements is presented. The system is able to collect a great number of data, up to a pulse repetition rate of 100kHz, during the acquisition phase, thus allowing an off‐line analysis of PD data. After a description of the instrument, some experimental tests performed on epoxy specimens are here presented in terms of amplitude, phase and energy resolved histograms. Finally, emphasis is given to the very interesting use of the instrument for pattern recognition techniques in the discrimination and classification of discharges in HV components.
Partial discharges on IGBT modules: Are sinusoidal waveforms sufficient to evaluate behavior?
2014
In recent years, the increasing use of AC-DC converters, especially in the field of renewable energy sources has led to the implementation of new modulation techniques, in particular the ones based on the pulse width modulation. The purpose of the present work is to verify the different behavior that is obtained when the components are subjected to the partial discharge test carried out with a sinusoidal waveform, and when they are subjected to PWM stress-type, similar to the actual signal generated by this type of electronic components. By considering equal rms value of the fundamental sine wave, the comparison has shown different partial discharges patterns.