Partial Discharge characterization based on leakage current pulses waveform for contaminated glass insulator string

Partial discharge (PD) is an electrical discharge event that does not completely bridges the electrodes in the insulation systems under applied field. Although PD does not cause immediate breakdown of the insulation, it may affect the insulation performance in the long term due to repetition of PD events. The occurrence of PD causes leakage current (LC) to flow, thus an attempt to characterize PD based on LC pulses waveform is presented in this paper. Results show that PD can be characterized (according to their occurrence with respect to the AC supply) as follows: corona discharge occurring in lightly contaminated insulators, surface discharge occurring in medium contaminated insulators and finally internal discharge occurring in heavily contaminated insulators. The ability to distinguish the type of PDs from the LC waveform could be used to monitor and predict the condition of the insulator. The outcome can be incorporated in a conditioning monitoring system

Effect of contaminant flow-rate and applied voltage on the current density and electric field of polymer tracking test

E1ectrical failure due to surface discharge on the insulation material will cause material degradation and eventually leads to system failure. The flow of leakage current (LC) on the insulator surface under wet contamination was used as the technique for determining the materiel degradation level. According to IEC 60587 standard, the LC exceeding 60 mA for more than two seconds is considered as failure. The analysis of electric field and current density distributions on the linear low-density polyethylene (LLDPE) and natural rubber blend material using finite element method (FEM) analysis was conducted. The physical parameters used in FEM simulation were applied voltage and contaminant flow rare which is in term of contaminant conductivity. Tracking test condition of IEC 60587 standard was applied as the reference work in simulation using FEM software of QuickField. The results show that the electric field and current density were critical in higher applied voltage and contaminant flow rate. The highest average and maximum current density and electric field reported in both applied voltage of 6kV and flow rate of 0.90 mlmin-1

Compact high-voltage pulse generator for pulsed electric field applications: lab-scale development

Square wave pulses have been identified as more lethal compared to exponential decay pulses in PEF applications. This is because of the on-time which is longer causes a formidable impact on the microorganisms in the food media. To have a reliable high-voltage pulse generator, a technique of capacitor discharge was employed. Four units of capacitor rated 100 μF 1.2 kV were connected in series to produce 25 μF 4.8 kV which were used to store the energy of approximately 200 J. The energy stored was discharged via HTS 181-01-C to the load in the range of nano to microseconds of pulse duration. The maximum voltage applied was limited to 4 kV because it is a lab-scale project. The electrical circuit diagram and the development procedure, as well as experimental results, are presented

Application of PDC analysis to identify effect of electrical tracking on conductivity of LLDPE-NR nanocomposite

Polymeric nanocomposites are widely used for high voltage outdoor insulating application due to their good electrical performance. Recently, SiO2, TiO2 and MMT nanofillers are being used as filler because there are listed as main nanofiller commonly used in electrical engineering. Natural rubber (NR) was used because the nature of the interphase is found to affect viscoelasticity and it develops several interphases with the Linear Low-Density Polyethylene (LLDPE) matrix. One of the problems associated with outdoor polymeric insulators is tracking of the surface which can directly influence the reliability of the insulator. This paper presents the outcome of an experimental study to determine the conductivity level of the LLDPE-NR compound, filled with different amount of SiO2, TiO2 and MMT nanofiller using Polarization and Depolarization Current (PDC) measurement technique. LLDPE and NR with the ratio composition of 80:20 were selected as a base polymer. Results show that different compositions as well as the surface physical conditions affect the PDC measurement result

Effect of switching method in polarization and depolarization current (PDC) measurement technique

Switching method in Polarization and Depolarization Current (PDC) measurement technique is an appealing area to look at, especially in terms of its behavior over time based monitoring. Previous researches on this technique did not deliberate the effect of switching method in its measurement analysis. Most of the researchers use a conventional HV relay that acts as a switching component. This paper studies the behavior of PDC measurement results and its relationship between the types of switching methods used. It is due to the research hypothesis where different switching method produces distinctive PDC measurement results. Determination of which optimal method that suit with this technique can be made by comparing PDC measurement results; the result which analogous to the reference is considered as the finest method. Two different switching methods were applied in this research, which are HV relays and series-connected of 600V, 30A, Insulated Gate Bipolar Transistor (IGBT

Identification of acoustic signals of internal electric discharges on glass insulator under variable applied voltage

A Partial Discharge (PD) is an unwanted phenomenon in electrical equipment. Therefore it is of great importance to identify different types of PD and assess their severity. This paper investigates the acoustic emissions associated wi1h Internal Discharge (ID) from different types of sources in the time-domain. An experimental setup was arranged in the high voltage laboratory, a chamber with an electrode configuration attached to it was connected to a high voltage transformer for generating various types of PD. A laboratory experiment was done by making the models of these discharges. The test equipment including antennas as a means of detection and digital processing techniques for signal analysis were used. Wavelet signal processing was used to recover the internal discharge acoustic signal by eliminating the noises of many natures

Fiber optic acoustic sensor based on SMS structure with thin polymer diaphragm for partial discharge detection

This paper proposes a fiber optic acoustic sensor (FOAS) based on a single-mode fiber - multimode fiber - single-mode fiber (SMS) structure attached to a thin polymer film used as a diaphragm. The diaphragm was specially developed to enhance the sensitivity towards the acoustic pressure-wave resulted from the partial discharge (PD) events. The sensitivity and signal-to-noise ratio (SNR) characterizations of the FOAS without and with a thin polymer film were performed. Both time-resolved and phase-resolved partial discharge (PRPD) patterns measurements were carried out in air and oil media. The experiment was conducted with three-electrodes using FOAS in conjunction with the conventional PD measurement as per IEC 60270 standard. The sensor achieved a sensitivity up to −31.21 dBm and −30.8 (0 dBm is defined as 1V/µBar) using broadband and tunable light source, respectively. The discharge characteristics pattern of FOAS was verified with IEC 60270 standard, and the patterns of FOAS resembled IEC 60270 standard. The proposed FOAS was capable for detecting the PD using both broadband and tunable laser lights. The use of the thin polymer film had a significant impact on the acoustic sensitivity. With the simple, low-cost design structure and free from electromagnetic interference, FOAS is found to be suitable as an in-situ sensor for detecting the acoustic signals of partial discharge and can be utilized inside the transformer

Application of Polarization and Depolarization Current in High Voltage Insulator - A Review

Deterioration of cable insulator can be caused by many factors such as aging, fault and breakdown. These factors are caused by the presence of moisture, impurities and heat due to high temperatures in an insulator. The maintenance and replacement for insulation system in power cables, power transformers and electric machine stator are generally expensive and time consuming. Thus, the performance and ability of an insulator can be monitored through polarization and depolarization current (PDC). Polarization and depolarization current (PDC) is a non-destructive test method that is used to analyse many factors that affects the behaviour of an insulator in time domain. This paper presents the review on application of polarization and depolarization current test method on different type of insulator. The factors that affects the performance of different type of insulator will be discussed in this paper. Moreover, the theory of polarization and depolarization current will be explained in order to understand the behaviour of polarization and depolarization current curve when fault occurs. Last but not least, this paper will provide a review on the different type of factors that affects the performance of different types of insulation

Characterization of leakage current on high voltage glass insulators using wavelet transform technique

The measurement and analysis of leakage current (LC) for condition-based monitoring and as a means of predicting flashover of polluted insulators has attracted a lot of research in recent years. Leakage current plays an important role in the detection of insulator's condition. This paper proposes a method for reducing the noise included in the current signal. The tests were carried out on cleaned and polluted glass insulators by using surface tracking and erosion test procedure of IEC 60587. Wavelet analysis method is used to compress the leakage current data. Experimental results shows that the actual signals of leakage current are related to the levels of insulator contamination

Polymer nanocomposites in high voltage electrical insulation perspective: a review

Polymer nanocomposites have attracted wide interests in various industries. This new class of material is capable of providing significant improvements in combined electrical, thermal and mechanical properties. Although the potential use of polymer nanocomposites in electrical insulating industry has only recently begun to be explored, a great number of researches have been conducted with regards to high voltage electrical insulation performance. However, it is found that the fundamental physics and chemistry concerning the property enhancement due to the incorporation of nanocomposites is still poorly understood, and there is still room for improvement in this research area. This paper serves to highlight some of the past developments of polymer nanocomposites and to inspire some potential fields that can be explored in high voltage electrical insulation perspective. Effect of the electrical discharges that causes the surface tracking and partial discharge phenomena on the polymer nanocomposites are the main subjects to be discussed in this pape