A critical review on soil ionisation modelling for grounding electrodes

Grounding electrode resistance non-linearly changes under impulse conditions due to soil ionisation phenomenon. Several models have been proposed to model soil ionisation for grounding electrodes applications. However, to date, there is yet an attempt made to compile all these works into a comprehensive review article. Therefore, this paper is written with the objective of summarizing all related works in this field as a one- stop reference. With reference to the literature, this paper is written to summarize the working principles of the soil ionisation models as well as the accuracy and performance analysis of the models. This paper, particularly highlights the deficiencies of the available models in terms of accuracy and performance. This knowledge will contribute to the development of a new accurate and efficient soil ionisation model

Aging detection of glass disc insulator by using infrared camera

Suitable diagnostic techniques for outdoor glass insulators are important for ensuring the reliablilty and stability of power system. The possibility of insulator flash-over increases, especially when the insulator is covered by pollution layers or has an internal defect. In this paper, a new technique to detect the pollution level and invisible damage by measuring the surface temperature of glass disc insulators is proposed. A high definition camera had been used to determine the surface temperatures of four glass insulators. The effects ofapplied voltage on the surface temperature and its distribution were studied. The results show the possibility of using the infrarad camera to detect the aging level and invisible damages of the glass insulators

Leakage current based thermal modeling of glass disc insulator surface

The stability of transmission lines relies on the health of the insulators, such as glass string insulators, which may occasionally flashover during an overvoltage. The likelihood of flashover increases notably when the glass insulator is wrapped by a wet contaminant layer. In this paper a study of the surface thermal profile of glass disc insulators insulation had been carried out for both clean and polluted surfaces. A finite-element simulation with time dependent model was carried out using COMSOL Multiphysics software. The variation of the insulator surface temperature with applied voltage as well as with pollution layer thickness is explained. The results illustrate the significant effect of pollution conductivity on heat propagate along the surface of the glass insulators with the increase higher voltages’ magnitudes. Study of the aging level impact on a steady state thermal for glass insulation surface is also carried out

An improved circuit-based grounding electrode considering frequency dependence of soil parameters

This paper presents the simulation of circuit-based vertically oriented grounding electrodes with the consideration of frequency dependence of soil resistivity and permittivity. The resistivity and permittivity were determined using equations proposed by Sundae and Dwight and the frequency dependence properties were modelled according to Scott's model. It was found that the voltage response was highly affected by the frequency, especially at high soil resistivity of 1000 ω and above (up to 4% decrease in voltage response). As for the low soil resistivity cases, the voltage response was less affected by the frequency, which is 1.4% and 1% lower for soil resistivity of 100 ω and 10 ω respectively. Obviously, the current circuit-based model (frequency independent model) tends to provide overestimated results. Therefore, the effect of frequency on the soil resistivity and relative permittivity should not be neglected when determining the transient performance of grounding electrode in order to obtain accurate results

The level of creativity in English writing among Jordanian secondary school students

The aim of this study is to explore the level of creativity in English writing among Jordanian secondary school students.The researchers have used a random sample of 100 students of secondary school students in Irbid and Amman cities in Jordan.Adapetd Torrance Test of Creative Thinking (TTCT) was used to measure their creativity in English writing.TTCT test is thought to be the best test to evaluate the creativity dimensions of students in writing.TTCT assesses fluency or the number of ideas; flexibility, the variety of categories in the answers; and originality, which consists in considering innovative answers, neither familiar nor inappropriate.The results of the study showed that the respondents fall in the moderate level of creativity

Modelling of electroluminescence in polymeric material using dimensional analysis method: effect of applied voltage and frequency.

Electroluminescence (EL) method has been used by several researchers to observe the behaviour of an aged polymeric material. EL is a phenomenon that occurs when the atoms of a material are being excited due to the application of and external high electrical stresses. The changes in the energy level of these excitation states can be used as an indicator for the initiation of electrical ageing. There are several factors that affect the behaviour of EL emission such as, among others, applied voltage, applied frequency, ageing of material and types of materials and gases used are discussed in this paper. A mathematical approach relating these factors and the intensity of EL is proposed through the aid of Dimensional Analysis method. A close relationship is obtained between experimental and simulation that suggests this mathematical approach can be utilized as a tool to predict electrical ageing of insulation material

The correlation of statistical image and partial discharge pulse count of LDPE-NR composite

High voltage insulation must be designed in such a way that it is very resistant to ageing including that from partial discharge (PD). Many studies were previously carried out on composites based on low density polyethylene (LDPE). However, the use of natural rubber (NR) and nanosilica (SiO2) in the LDPE-NR based composites is relatively new. Furthermore, the PD resistant performance of the composites is yet to be extensively researched. This work aims to analyze the correlation between PD pulse count and its related image to interpreting the effect of PD signals. The results show there is a strong correlation between PD pulse count and the statistical image. The results indicate that the surface image statistical analysis can be used as a tool to justify the total of the PD pulse count on the surface for different samples of composite

Conductive and inductive coupling between faulted power lines and buried pipeline by considering the effect of soil structure

The AC total interference of faulted power lines to gas pipelines sharing the same right of way, which may pose a threat to operating personnel and equipment, was studied. The main advantage of this work is to determine the effects of different soil structures on the induced voltage for various soil resistivities. Two main approaches were used to compute the induced voltages, namely the method of moment (MOM), which is based on electromagnetic field theory, and the circuit based method, which uses the circuit grounding analysis to compute the conductive interference and the circuit based models to compute the inductive interference. A 10-km-long parallel pipeline-transmission line model was developed. The soil resistivity was varied, and the induced voltages obtained from both approaches were compared. Soil resistivity and soil structure are important parameters that affect the AC interference level. The results of the study show that the earth potentials and the metal GPRS are independent. Higher soil resistivity causes the tower ground resistance to increase, thus making the shield wire’s attractiveness as a fault current return path to increase, which in turn forces the induced net EMF and the cumulative GPR in the pipeline to reduce

Flexible Wearable Antenna on Electromagnetic Band Gap using PDMS substrate

A robust and low-profile electromagnetic band-gap (EBG) based on flexible wearable antenna covering 2.4 GHz frequency band is presented. The incorporated EBG with antenna reduces the  radiation into the human body around 17 dB and decreases the impacts of frequency detuning. The overall dimension of the antenna integrated with EBG is 56 x 56 x 4 mm3 with relative impedance bandwidth of 8.3% is achieved. The proposed design has improved the gain up to 7 dBi. Specific absorption rate (SAR) assessment is also studied to certify the performance of the antenna when it is located proximity to human tissue. The flexible antenna with aforementioned performances could be chosen as a good candidate for integration into a range of wearable devices for medical application

A novel green antenna phase-shift system with data acquisition boards

A novel green phase shifter system is proposed in this research. The system is developed by a combination of reconfigurable beam steering antennas and data acquisition (DAQ) boards. A combination of two reconfigurable beam steering antennas, located side-by-side, forms a spatial configuration structure with a fabricated ‘green’ element plank of rice husk placed in between. The concept of a spatial configuration technique has been ‘mutated’ by shifting the structure of spiral feed line and aperture slots of first beam steering antenna by as much as 45 ◦ . The PIN diode switches connected to the DAQ boards enable the intelligent capability of the spatial antennas. The activation of certain degree radiation patterns of either the first beam steering antenna or the second beam steering antenna depends on the memory of the DAQ boards — Beam Manager. When an intruder comes from the cardinal angles of 0◦/ 360◦, 90◦, 180◦, or 270◦, its range and angles’ location will be automatically detected by the first antenna through the output ports of the 1st DAQ: P1.0, P1.1, P1.2, and P1.3. The second antenna is then activated by the output ports of the 2nd DAQ: P2.0 up to P2.3, to adaptively maneuver the beam towards four different ordinal directions of 45◦, 135◦, 225◦, and 315◦