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Corona discharges caused by water droplets on the surface of polymeric insulators can affect the long-term reliability of the component by lowering the surface hydrophobicity encouraging surface discharges. It is well-known that droplet-initiated discharges behave differently under AC and DC field stress affecting the hydrophobicity of polymeric outdoor insulation materials. The presented investigations...
We have been investigating sterilization of liquid food by high electric field pulse. In this paper, high electric field pulse is applied to aqueous solution with Escherichia coli changing the components of the solution. As results, the survival rate of samples decreases with the ion concentration in aqueous solution. We consider that the performance of high electric field pulse sterilization depends...
This paper studies the electric breakdown problem of a semi-permeable crack in piezoelectric material under combined mechanical and electric loads. According to Stroh formalism, the differences of the electric potential and the displacement of the crack are first derived and the quadratic equation containing the electric displacement inside the crack is obtained. Meanwhile, the electric field is also...
In this paper the combined electro-thermal life model for the insulation of power cables is extended in order to include the volume enlargement law, whereby the statistical breakdown behavior with the increase of insulation volume is accounted for. In this way, a new comprehensive model is obtained, whose usefulness lies in that it includes the effect of volume enlargement - beside that of electrical...
Space charge accumulation characteristics in Epoxy resin with various heat treatments were investigated under DC high stress using as pulsed-electro acoustic (PEA) method. Epoxy resin has been used as sealing material for semiconductor devices. Recently, a new semiconductor like silicon carbide (SiC) has been developed to use it at high temperature environment. However, the conventional epoxy resin...
Polyethylene has been one of the widely studied polymeric insulation materials. One of the major issues related to polymeric materials is the easy formation of space charge which may cause electric field enhancement. In this paper, a numerical simulation based on a bipolar charge injection/transport model is used to obtain characteristics of space charge in polyethylene under the combined AC and DC...
The ability to withstand high voltages in vacuum is one of the key reasons for its choice as an insulation medium for distribution-class voltage fault interrupters. However, the dielectric performance of vacuum is still not fully understood, sometimes leading to contradictory results. In this paper, high voltage withstand test results are presented. The subsequent location and quantity of the discharge...
Surface flashovers that are initiated from the triple junctions in vacuum interrupters can restrict their overall performance of vacuum's solid insulation especially for the voltage ranges of 72.5 kV and above. This has to be taken into account for the insulation coordination of vacuum interrupters. A basic model of a 72.5 kV vacuum interrupter was simulated in order to study the electric field stress...
Energy harvesting has been studied with great interest in recent years. Ambient vibration is a potential energy resource for low-power devices or electronic devices in extreme/remote area. Methods on enhance the energy conversion amount has been long been a main subject in energy harvesting field. The present study developed a precise model working under hybrid of electrical and mechanical excitations...
A set up originally designed for e31f measurements of piezoelectric thin films was operated in a way to assess life time issues with simultaneous recording of polarization change, PV-loop integral, and piezoelectric beam deflection. A 1μm thick PZT 53/47 thin film was subjected to 109 unipolar pulses with 150 kV/cm driving voltage at 100 kHz and 50 % duty cycle. The observed fatigue was restricted...
Piezoelectric materials have interesting properties for actuator or sensor applications. The direct conversion of electrical to mechanical power is a key property to build lightweight structure. However their small displacement capabilities oblige the designers to put them in amplification structure such as benders. In order to size them at best an accurate model for the stress and electric field...
Understanding ferroelectricity in polymers presents a formidable challenge, as specific requirements in the crystalline ordering of the polymer chains must be met that run counter to the propensity of polymers to form largely disordered structures. Consequently, poly(vinylidene fluoride) (PVDF:[-CH2-CF2-]n and its copolymers formed with poly(trifluorethylene) (PFTE:[-CHF-CF2-]n have been investigated...
Space charge behavior and conduction current in XLPE and annealed LDPE under DC high electric field were investigated. One of the reasons for the different breakdown property in XLPE from that in LDPE may be based on the existence of cross-linking by-products in XLPE. Furthermore, a thermal history in cross-linking process for XLPE under high temperature may also cause of the difference. It is generally...
Being a part of the power cable network, the cable terminal is more likely to have issues. And these problems usually derive from production or installation. In a regular PD check, an internal discharge caused by a design flaw in the cable terminal was found. And this design has been widely applied in the real practice. Aiming at this kind of defects, this paper figured out the causes of the fault,...
The application area of pulsed power technology has been expanding into biological and medical fields. In particular, nanosecond pulsed electric fields (nsPEFs) could directly act on intercellular components without destruction of cell membrane. Clarification of biological effect of endoplasmic reticulum (ER) stress response by nsPEFs would suggest new methods of prevention or therapy of disorders,...
This paper presents a 2d finite-element analysis for a 33-kV, three-phase, three-core cross-linked polyethylene (XLPE) power cable termination. To enhance the cable termination lifetime, many factors are examined to reduce the electric-field intensification and the induced current density in the copper sheath. The aim of this simulation is to investigate how the electric and the induced current density...
In high voltage engineering, optimization of electric field distribution is directly related with the design of high voltage electrode surface. Various field optimization techniques are in use and this paper presents a new method based on the biogeographically isolated habitats for the optimization of high voltage electrode surface. This new method is known as Biogeography Based Optimization (BBO)...
We investigate current collapse in GaN MIS-HEMTs for >600 V operation. Extreme trapping leading to total current collapse has been observed after OFF-state stress at high voltage. We attribute this to high-field tunneling-induced electron trapping (“Zener trapping”) inside the AlGaN barrier or the GaN channel layers. The trapping takes place in a narrow region right under the edge of the outermost...
Silicon carbide (SiC) is an inorganic material which has non-linear conductivity characteristics. When mixed nano-size SiC into silicone rubber (SIR), the composites can achieve non-linear conductivity characteristics also. In this paper, the non-linear conductivity properties of 5wt%, 15wt%, 30wt%, 45wt% nano-SiC/SIR composites are investigated. The relationship between conductivity and electric...
This paper focuses on analyzing the electric field and temperature distribution in a typical stress grading system used in medium voltage rotating machines under pulse width modulation voltage source conditions. Two analysis models for electric field and heat transfer processes are developed to take into account the nonlinear relationship between the electric field and the electrical conductivity...
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