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

Characteristics of grounding performance at Taman Bukit Perdana

Grounding system is one of the important part during installation of power systems. The function of grounding system is to enable protection to the power system in case of any current leakage or lightning strike. A grounding system will disconnect the circuit as soon as the fault current flows through the earth [1]. Every potential connection or equipment that may cause the current leakage must be grounded. In a simple way, it can be defined as the system to protect and stabilize the operation for human and equipment during fault conditions

Effect of broken skirts on voltage distribution along insulator strings

The existence of broken glass insulator as part of a complete string may alter the local voltage distribution. A finite element software is used to study the effect of broken glass insulator (stub) to the voltage distribution profile. In this paper we present the voltage distribution profile across single and ten units of glass insulator string with different locations. The results show that the presence of broken insulator under dry conditions and without contaminants affects the distribution profile of voltage. The local voltage distribution is certainly altered when the stub is present at any location in the string. However, maximum percentage increase in voltage is experienced when the stubs are located near to the ground (GND) end. This result helps to explain the ability of transmission line insulation system to operate satisfactorily even with the presence of stubs along the string

Smart distribution board overload detector by using microcontroller

A statistic by Economic Planning Unit (EPU) on the electricity growth in Malaysia has shown an increment in line with economic growth [1]. In line with government policies, the energy supply industry has been molding itself to cater to the rapid development of the nation in hopes of creating a better and smarter nation [2]. There are many developments and implementation of smart energy consumption to save energy and cater to future energy challenges

Electrical withstand performance of Malaysian based palm oil under influence of HVDC stress

Overvoltage is a phenomenon where electrical waveform applied to circuit or device exceeds normal operating parameters. The sources of overvoltage are often unpredictable and can lead to permanent degradation, failure or temporary malfunction of devices and systems. Equipment running with HVDC needs to be equipped with a proper protection system and insulation strength properties better than typically being rated to the HVAC system

Top oil heat distribution pattern of ONAN corn oil based transformer with presence of hot spot study using FEMM

Transformer thermal modelling is a crucial aspect to be considered as this may help the determination of heat capacity of transformer. This paper present, simulation study on Oil Natural Air Natural (ONAN) transformer heat distribution pattern with and without presence of hot spot temperature (HST). This paper aims to compare the effects of different HST value at different locations inside the transformer unit as well as to evaluate the top oil thermal behaviour of corn oil as cooling mechanism in a transformer. To achieve aforementioned objectives, three HSTs were introduced to the 30 MVA transformer winding to find the total heat build-up in the top of the transformer tank. The outcome of thermal properties is examined using x-y temperature plot. From the results found that the location of HST affects overall transformer’s temperature. HST at the top of the winding give a significant effect compared to when HST is at the bottom of the winding. It is also evident that the usage of corn oil reduced the temperature distribution of the transformer. The findings suggest that the temperature distribution study especially on transformer is important to monitor in-service transformer in a non-invasive manner

Comparison on space charge and voltage distribution of high voltage insulator subjected to different contamination levels

This paper presents the study of space charge distribution on high voltage (HV) insulators under different levels of contamination. Two types of HV insulators were used in this work particularly glass and porcelain insulators. A string of 4-unit glass and porcelain insulators with 33 kV of lines voltage was designed and simulated using QuickfieldTM software. Four levels of contamination layer with different thickness have been applied on the surface of insulators to observe the effect of space charge distribution. Simulation results show that different types of insulators used at transmission lines give different effects on charge and voltage distribution. It is also found that the amplitude of charge for a single porcelain insulator is much higher compared to a single glass insulator. Similarly for a string of 4-unit insulators, the voltage distribution along the creepage distance of porcelain insulators is much higher compared to glass insulators under all contamination levels

Space charges analysis on insulator with uniform layer contamination effect

High voltage direct current (HVDC) transmission provides an attractive alternative for bulk power transfer. However, HVDC transmission may have loss about half per unit length of high voltage alternating current (HVAC) at the same amount of power carried. This is due to the space charge formation around the conductor in HVDC cables. It is known that the presence of space charge inside an insulator may distort the local electric field and surface energy. This paper investigates the effect of electrostatics for space charge, electric field and surface energy in the HVDC cable in clean and contaminated conditions. The effect of uniform layer contamination from oil, sandstone and fresh water was conducted on 11 kV XLPE cable using finite element software under electrostatics study. The contamination layer was created around the XLPE cable by multifarious the radius of layer contamination from the conductor. The simulation results show that enlargement of contamination layer radius by 1.0 mm (light), 1.5 mm (medium) and 2.0 mm (heavy) resulted in the reduction of surface energy by 20% and electric field by 22% but increase the space charge amplitude by 76%. The study also found that fresh water can be considered as the worst contamination compared to oil and sandstone

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 with 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