N. A. M. Jamail

Effect of nanofillers on the polarization and depolarization current characteristics of new LLDPE-NR compound for high voltage application

Polymeric nanocomposites in which the nanosize fillers are evenly distributed in the polymer material attract attention as an insulating material due to their ability to enhance the materials performance properties of electrical and mechanical. For high voltage (HV) insulation application, one of the targets is to obtain new insulators with improved dielectric properties. This paper presents the outcome of an experimental study to determine the conductivity level of the linear low-density polyethylene- (LLDPE-)natural rubber (NR) compound, filled with different amount of SiO2 and TiO2 nanofiller by using the polarization and depolarization current (PDC) measurement technique. linear low-density polyethylene (LLDPE) and natural rubber (NR) with the ratio composition of 80u2009:u200920 are selected as a base polymer. The experiment was conducted to find PDC pattern and conductivity variations of each of the LLDPE-NR/SiO2 and LLDPE-NR/TiO2 samples. The results show that the addition of SiO2 filler exhibited less conductivity compared to TiO2 filler with certain percentage. From the study, it can be concluded that LLDPE-NR/SiO2 is a better insulator compared with LLDPE-NR/TiO2.

Comparative study on conductivity using Polarization and Depolarization Current (PDC) test for HV insulation

Polarization and Depolarization Current ( PDC) testing is a non-destructive dielectric testing method to determine the conductivity of insulations. It is one of the dielectric diagnostic techniques based on time domain measurement. PDC measurement technique has gained immense popularity due to its ability to assess the condition of HV insulation. PDC measurement can provide information about the conductivity within the initial periods (seconds) after a DC step voltage application. This paper present the review and comparison results from several published papers on application of PDC method in finding the conductivity of the various types of insulators. The scope of the review covered solid and liquid insulations types. In this paper, for solid insulation the studied was focused one ables insulations, electric machine stator insulation and paper insulator in power transformer insulation. For liquid insulation, the review and comparison was done on the biodegradable and mineral transformer oils. The review results show that the PDC technique successfully give indication on level of conductivity of the HV insulation materials.

Comparative Study on Conductivity and Moisture Content Using Polarization and Depolarization Current (PDC) Test for HV Insulation

The Polarization and Depolarization Current (PDC) measurement is an efficient and effective diagnostic technique based on time domain measurement, for evaluating the high voltage insulation condition. This paper presents a review and comparison results from several published papers on the application of the PDC method to finding the conductivity and moisture content of various types of insulators. For solid insulation, the study was focused on cable insulation, electric machine stator insulation, and paper insulator in transformer insulation with different conditions. For liquid insulation, the review and comparison was done on biodegradable and mineral transformer oils, with fresh oil condition, and aged condition. The results from previous researchers tests were complied, analyzed and discussed, to evaluate the application of the PDC method to monitor the conductivity and moisture of HV equipment insulation systems. From the review results, the PDC technique successfully gives an indication of the conductivity and moisture level of high voltage insulation.

Electrical tracking characterization of LLDPE-Natural Rubber blends filled with nanofillers

Electrical tracking is a process of formation of permanent conducting path across the insulating material due to the surface erosion under high voltage application. The existing of leakage current (LC) on the wet contaminated material surface causes the generation of surface discharges that resulted to the material degradation. Electrical tracking test can be indicated as failure when LC exceed 60 mA for more than two seconds or at least 25mm of formation of carbon track or erosion breaks through the thickness of the sample. In this paper, a new formulated thermoplastic elastomer material which composed of Linear Low-Density Polyethylene with Natural Rubber (LLDPE/NR) filled and unfilled with different percentage of silicone oxide (SiO2) or titanium oxide (TiO2) as nanofiller is presented. The compound was tested based on IEC 60587 inclined plane tracking test procedure. The analysis of LC and rate of carbon track development were also conducted. Surface morphology analysis was carried out for investigating the degraded surface structure of the materials. The formulation of pure LLDPE/NR has shown the highest average leakage current whereas the composition of LLDPE/NR-TiO2 with 1 % wt of nanofiller was found to be the best electrical tracking resistance due to the lowest average leakage current and no carbon track appeared. The blends of LLDPE/NR-SiO2 show that low average leakage current and no carbon track in less than 5 % wt nanofiller. The usage of 5% wt or more for both nanofiller had shown the worst in carbon track formation.

Design of HV switching for polarization & depolarization current measurement

The method of assessing the insulation condition in high voltage (HV) electrical equipments can never be overemphasized. Over the years, several method of assessing the insulation condition have been researched & used by many researchers. One of these methods is using the dielectric response of the materials to determine the Polarization and Depolarization Current (PDC). PDC is a non-destructive assessment method that combines a sequence of switching operations & current measurement for time domain response. In this paper, the HV switching sequence for a PDC assessment was designed & built to fulfill the PDC assessment basic theory. The switch was applied on three materials used in HV insulation to determine their polarization current (ip) & depolarization current (id). Test duration for both ip & id were 10000 seconds and the test results are presented as a current pattern. The current pattern is consistent with the theoretical current wave PDC pattern from literatures thereby confirming the validity of the built switching device.

Polarization & depolarization current (PDC) measurement in cellulose insulating materials

The study of electrical insulating materials can never be overemphasized. When these materials are subjected to either electrical or thermal stresses each one respond in a uniquely different way from one another. The response of insulating materials to its stressors is a stochastic process with varying dependent variables. The discovery of newer or composite insulating materials, having better electrical properties, have further deepened this lack of understanding. Researchers and engineers have utilized the dielectric relaxation in the materials as an assessment tool. Polarization and Depolarization Current (PDC) is one of such assessment tools to measure the relaxation current when a sudden stress is applied or removed. This paper presents study of the relaxation current in Kraft paper and how moisture diffusion in it affects the conductivity of the Kraft paper. This assessment technique was done using a multi physics software; COMSOL Multiphysics. COMSOL Multiphysics has been chosen because dielectric relaxation has a multidisciplinary science of physic, chemistry and electrical engineering involved in the process. 100V dc was applied across cellulose molecule and the resulting conductivity, σ and moisture diffusion was measured and presented. The result shows the interesting relationship between conductivity & changes in moisture in the solid insulation.

Potential and Electric Field Characteristics of Broken Porcelain Insulator

A new type of leaky-wave antenna (LWA) using half-mode substrate integrated waveguide (HMSIW) as the base structure is proposed in this paper. The structure consists of an array of slot, antenna designed to operate in X band applications from 8 to 12 GHz. HMSIW preserves nearly all the advantages of SIW whereas its size is nearly reduced by half. The antenna radiates one main beam that can be steered from the backward to the forward direction by changing frequency.Internet of things (IoT) has described a future vision of internet where users, computing system, and everyday objects possessing sensing and actuating capabilities are part of distributed applications and required to support standard internet communication with more powerful device or internet hosts. This vision necessitates the security mechanisms for end-to-end communication. A key management protocol is critical to ensuring the secure exchange of data between interconnecting entities, but due to the nature of this communication system where a high resource constrained node may be communicating with node with high energy makes the application of existing key management protocols impossible. In this paper, we propose a new lightweight key management protocol that allows the constrained node in 6loWPAN network to transmit captured data to internet host in secure channel. This protocol is based on cooperation of selected 6loWPAN routers to participate in computation of highly consuming cryptographic primitives. Our protocol is assessed with AVISPA tool, the results show that our scheme ensured security properties.

Breakdown Characteristic Analysis of Paper- Oil Insulation under AC and DC Voltage

This paper presents the study of breakdown characteristic of Kraft paper insulated with two different types of insulating fluid, which are Palm oil and Coconut oil. Palm oil and Coconut oil are chosen as the alternative fluid to the transformer oil because it has high potential and environmentally-friendly. The Segezha Kraft papers with various thicknesses (65.5 gsm, 75 gsm, 85gsm, 90 gsm) have been used in this research. High Voltage Direct Current (HVDC), High Voltage Alternating Current (HVAC) and carbon track and severity analysis is conducted to observe the sample of aging Kraft paper. These samples have been immersed using Palm oil and Coconut oil up to 90 days to observe the absorption rate. All samples started to reach saturation level at 70 days of immersion. HVDC and HVAC breakdown experiments have been done after the samples had reached the saturation level based on normal condition, immersed in Palm oil and immersed in Coconut oil. All samples immersed in liquid show different breakdown voltage reading compared to normal condition. The analysis of carbon track and severity on surface has been done using Analytical Scanning Electron Microscope (SEM) Analysis. The results of the experiment show that the sample of Kraft paper immersed in Palm oil was better than Coconut oil immersed sample. Therefore the sample condition was the main factor that determines the value of breakdown voltage test. Introduction

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 results.

Conductivity variation observed by polarization and depolarization current measurements of high-voltage equipment insulation system

Nondestructive and time domain dielectric measurement techniques such as polarization and depolarization current (PDC) measurements have recently been widely used as a potential tool for determining high-voltage insulation conditions by analyzing the insulation conductivity. The variation in the conductivity of an insulator was found to depend on several parameters: the difference between the polarization and depolarization currents, geometric capacitance, and the relative permittivity of the insulation material. In this paper the conductivities of different types of oil-paper insulation material are presented. The insulation conductivities of several types of electrical apparatus were simulated using MATLAB. Conductivity insulation was found to be high at high polarizations and at the lowest depolarization current. It was also found to increase with increasing relative permittivity as well as with decreasing geometric capacitance of the insulating material.