Partial discharge

About: Partial discharge is a research topic. Over the lifetime, 13997 publications have been published within this topic receiving 102058 citations. The topic is also known as: PD.

A neuro-fuzzy approach for the detection of partial discharge

Abstract: Dielectric surfaces exposed to partial discharges (PD) undergo aging, which is reflected by changes in the discharge pulse form. An approach is described in which fuzzy logic and neural networks are used in conjunction with the wavelet transform to identify the parameters in the PD pulse form for the purpose of classifying the aging phenomena due to partial discharge degradation.

Investigation on insulation material morphological structure of 110 and 220 kV XLPE retired cables for reusing

Abstract: Most of the 110 and 220 kV cables are in service till the end of life, but part of them would be out of service by refurbishment This research is focused on evaluating the cable insulation and determining whether the cable can be reused All the cables used in this research satisfactorily passed the AC voltage and partial discharge tests Then the fourier transform infrared spectroscopy, thermogravimetry analysis, differential scanning calorimetry, dynamic mechanical analysis, and tensile machine were used to analyze the insulation morphological structure and performance of 20 retired 110 and 220 kV crosslinked polyethylene cables obtained from the Beijing and Zhuhai districts The results show that the structure parameters which can represent the physical change and the irreversible chemical change of cables have obvious time dependence characteristic DSC result shows that crystallinity, melting range, and crystallization rate increase slightly with service years DMA experiment illustrates that the temperature of mechanical loss peak, Tγ, shifts to a higher temperature while the mechanical loss increases slightly and temperature dependency of storage modulus increases with service years The electrical treeing experiment utilized cable operated for 17 years, which is the longest operation year for the samples Compared with new cable, the cable operated for 17 years has a slight decrease in tree initiation time and an obvious increase in tree propagation time These experiment data show that the insulation material morphological structure is mainly stable, and the test results are also a contribution to the lifetime expectancy evaluation of the 110 and 220 kV XLPE cable

Partial discharge detection in oil with optical methods

Abstract: The partial discharge measurement is a very well known possibility to assess the quality of an insulation system of high voltage devices, because the life of high voltage equipment depends on the present of partial discharge. The aim is the detection of a beginning destruction in the electrical insulation as a result of electrical stress. A multiplicity of different partial discharge sources and their appearances show different physical and electrical characteristics. For the measuring, physical effects, such like optical, electrical and acoustical appearances, will be used. New methods for the detection of partial discharge have become more importance in last years. In the working field of technical diagnostics alternatives to the conventional partial discharge (PD) measuring techniques are looked for, with the aim to evaluate the insulation condition of electrical equipment.

Approach to partial discharge development in closely coupled cavities embedded in solid dielectrics by the lumped capacitance model

Abstract: The use of the typical ABC equivalent circuit for one cavity in solid dielectrics for internal partial discharge modelling has been common practice for many years. The introduction of an equivalent circuit for two closely coupled cavities permits the investigation of the interaction between discharges in such cavities in a solid dielectric when it is stressed by high AC voltages. In this model circuit, cavities and solid dielectric parts are represented as lumped capacitances, while the resistance and the inductance of the test voltage source are taken into consideration. By using a version of the Electromagnetic Transients Program (EMTP), the waveforms of the voltage across the two cavities, as well as those of the voltage across the neighbouring parts of the solid dielectric, have been traced, and the transient voltage stressing of these parts has been analysed for repetitive discharges in the two cavities.

Negative Coaxial Cylindrical Corona Discharges in Pure N2, O2, and Mixtures Thereof

Abstract: Direct‐current corona studies were made on coaxial cylinders with inner cylinder at negative potentials in pure N2, pure O2, and mixtures of 1 percent 10 percent O2 in N2, and on clean dry air from 27‐mm to 760‐mm pressure. Observations of current potential relations from field intensified ionization currents to as near breakdown as possible were made noting thresholds for current transitions, pulsed discharges and other oscillographic as well as visual appearances. Negative wire corona does not exist as such in truly pure N2. Unless a high series resistance was in the line once the critical region of potential was reached, the gap broke down to an arc. With current limiting resistor bombardment of the filament with positive ions from the low order pre‐discharge released enough gaseous impurity so that after six minutes the resistor could be removed and the internal resistance of the negative ion space charge near the anode held the current at 2000 μa. The behavior indicated that breakdown was preceded by a low current Townsend discharge that cleaned up or conditioned the filament. In all the negative wire studies the onset thresholds vary with the past history of the wire, and the threshold potential at higher pressures overshoots the minimum operating potential of the discharge once it has set in. Studies with 1 percent O2 indicate that the threshold discharge with clean gas is a continuous current with a diffuse glow which in time contracts to a cathode spot with Trichel pulses. Similar behavior applies to air at lower pressure. The negative wire in O2 shows very heavy predischarge currents with relatively small current jumps when random Trichel pulses appear, and further small current jumps when the fixed spot with regular Trichel pulses appears. There is evidence for a continuous heavy background of Townsend discharge along the whole wire until the visible spot and heavy pulsed discharge appears. The duration of Trichel pulses in pure O2 is two to ten times those in air with point to plane geometry and two to three times those in air with coaxial cylindrical geometry. Lower pressures in pure O2 show many current transitions and transitions between discharge forms.