Feasibility Study on Electrical Properties of 20 kV Polymeric Insulator Dry Test and Rainwater Test

Insulator is a very important equipment in an electric power system. Ceramic insulators have been widely used to support conductors in 20 kV power lines. The problem of ceramic insulators is that they are heavy, easily contaminated on the surface and require a lot of energy in the manufacturing process. Therefore, polymer insulators were developed. This paper presents the design of an epoxy resin polymer insulator with Titanium Dioxide (TiO2) as a nanofiller. The leakage current test was carried out in a high voltage laboratory by applying an AC high voltage of 50 Hz to the insulator dry conditions and the insulator wetted by rainwater contaminants. The results of the leakage current test in dry conditions are 487.6 μA, rainwater contaminated conditions are 594.93 μA, insulation resistance in dry conditions is 2.07 G-Ohms, and contaminated conditions are 1.41 G-Ohms. Based on the test results show that the insulator leakage current increases up to 22% when the surface of the insulator is contaminated with rainwater. Meanwhile, the insulation resistance decreased by up to 32% in conditions contaminated with rainwater. The value of leakage current and insulation resistance indicates that the epoxy resin insulator with TiO2 as filler is electrically feasible to use.

Mathematical modeling of polymer dielectric strength considering filling concentration

Enhancement of Dielectric strength is an important issue to enhance power system reliability. Insulation filling such as Alumina Trihydrate (ATH) and Silicon dioxide (Sio2) are used to enhance the dielectric strength of polymer insulator. The paper proposes a mathematical model of dielectric strength considering different temperatures and filling percentages using neural network. Moreover, comparison of filling materials is carried out through this model. The comparison shows the superiority of ATH in enhancing the dielectric strength of the polymer. Also, the obtained model will help in getting the best filling concentration without needing to repeat the tests which can be considered as a techno-economical solution to enhance the dielectric strength. Finally, the curve fitting is used to get the dielectric strength model not only as a function of filling concentration percentage but also as a function of temperature.

Reconfigurable Multifunctional Ambipolar Polymer Transistors with Improved Switching-off Capability Upon Non-Uniformly Distributed Compensation Potential

Ambipolar field-effect transistors allowing both holes and electrons transport can work in different states, which are attractive for simplifying the device manufactures and miniaturizing the integrated circuits. However, conventional ambipolar transistors intrinsically suffer from poor switching-off capability because the gate electrode is not able to simultaneously deplete holes and electrons across the entire transport channel. Here, we show that the switching-off capability of polymer ambipolar transistor is largely improved by up to 3 orders, through introducing non-uniformly distributed compensation potentials along the channel to synchronically tune the charge transport at different channel locations. Non-uniformly gate-stressed conjugated-polymer@insulator blend film induces non-uniformly trapped charges in the insulators, which consequently generates non-uniform compensation electrical field imposed in the conjugated-polymers. Both n-type and p-type operations with high mobility (2.2 and 0.8 cm2s-1V-1 respectively) and high on/off ratio (105) are obtained in the same device, and the device states are reversibly switchable, which provides a new strategy for three-level non-volatile memories and artificial synapses.

Finite Element Analysis of the Breakdown Prediction for LDPE Stressed by Various Ramp Rates of DC Voltage Based on Molecular Displacement Model

Predicting the electrical breakdown of polymers is critical for certifying the endurance and lifetime of high voltage power equipment. Since various factors contribute nonlinearly to the breakdown phenomena of polymer insulators, it is difficult to assess the impact of each factor independently. In this study, we numerically analyzed the breakdown phenomenon because of the ramp rate of the DC voltage applied to a polymer insulator, low-density polyethylene (LDPE), using the finite element method (FEM). To predict the breakdown initiation, we analyzed the relaxation time of the conduction current through the insulator as a significant indicator. The bipolar charge transport (BCT) model was used to analyze the charge behavior within the LDPE, and the breakdown voltage was predicted by incorporating the molecular displacement model. This analysis was conducted for a wide range of ramp rates from 10 to 1500 V/s. The current density was calculated using two different methods, namely the energy and average methods, and the results were compared with each other. The results of the numerical model were further verified by comparing with those from experiments reported in the literature.