Materials Literature
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Zinc oxide (ZnO) is a unique material that exhibits semiconducting, piezoelectric, and pyroelectric multiple properties. Using a solid-vapor phase thermal sublimation technique, nanocombs, nanorings, nanohelixes/nanosprings, nanobows, nanobelts, nanowires, and nanocages of ZnO have been synthesized under specific grow…
The influence of structure and physical-chemical nature of polymers on electret charge relaxation in fiber polymer materials based on various polymer matrix (polyethylene, polyamide, polypropylene), produced by melt-blown technology, was investigated in this work. It has been established, that increase of electret eff…
The present work is concerned with the development of a new technique for simultaneous measurements of space charge profiles and TSDC spectra on polymer sheets without manipulating the sample and dismantling the measuring cell. During the TSDC run, the space charge profile is measured at several temperature levels by…
Very narrow artificial tubes have been used to investigate the behaviour of discharges in conditions similar to those encountered in electrical trees. In the present study a discharge sequence measured prior to the formation of an electrical tree at the tube tip has been analysed to see if there was any evidence for t…
When superconducting power apparatuses and electronic devices are commercially available in the near future, polymers will play a decisive role in the design of electrical insulation. The working temperatures of superconductors regardless of low temperature superconductors at liquid helium temperatures or high tempera…
The presence of partial discharge is one of the most prominent indicators of defects and ongoing degradation processes in electrical insulation systems. Lately ns orders partial discharge signal measurements has become of major interest, because the waveforms of partial discharges are changed with the degradation of t…
In order to investigate the effect of surfactant on water tree generation, experiments were conducted using XLPE specimens containing various types of nonionic surfactants. The experiments were conducted while applying a voltage stress of 3 kV/mm at ambient temperature in copper sulfide and sodium chloride solutions.…
We have developed partial discharge current pulse waveform analysis (PD-CPWA) method in order to assess insulation degradation of solid insulators with degraded insulation performance. PD-CPWA focuses on the time transition of individual PD waveform parameters such as peak value, rise time, di/dt in a single PD curren…
Relevant standards such as the IEC60270 concentrate on a measurement frequency band below 1 MHz and on lumped, i.e. non-distributed test objects. On-line partial discharge measurements often require using higher frequencies to avoid noise interference. With respect to the basic gas discharge physics, the rise time of…
Space charge formation at interfaces between polyethylene and other polymeric materials were observed using a PEA method. Many polymeric materials are proposed to be used as the pre-molded joint for XLPE insulated cables. However, there are few investigations of space charge accumulation at the interface between diffe…
This paper reports on a study of the influence of the level of alumina trihydrate (ATH) on the electrical insulation properties and the tracking and erosion resistance of high temperature vulcanized silicone rubber (HTV-SIR). The electrical resistance of silicone rubber was measured using a high resistance meter. It d…
Based on the test results carried out on several types porcelain and AC composite insulators as well as a DC insulator in the artificial climate chamber, this paper puts forward the flashover performance of tested insulators at the atmospheric pressure of the altitude of 4000-meter and above concomitant with the conta…
It is known that space charge is formed in cables insulated with crosslinked polyethylene. It is assumed that the crosslinking byproducts or the crosslinked polymer morphology is responsible for the space charge. In order to examine these possibilities, low-density polyethylene, crosslinked polyethylene, and degassed…
Dependence of space charge distribution on voltage m application time is observed by pulsed electro-acoustic method in silicone rubber sample. Aluminum and copper are used as lower and upper electrodes, and a dc electric stress of 5-70 kV/mm is applied. Test results show that the primary space charges in samples are h…
Room temperature vulcanized (RTV) silicone rubber (SIR) coatings are used increasingly on outdoor HV porcelain and glass insulators and bushings when subjected to heavy pollution. An important property of the RTV-SIR coating is its ability to restore the hydrophobicity of the surface after a layer of contamination has…
The object of this paper is to clarify some of the items that regard space charge injection and accumulation in AC in polyethylene-based materials. In particular, the dependence of space charge injection threshold on supply frequency (from DC to 1000 Hz), as well as of space charge accumulation on electrical stress, f…
This paper discusses behavior of partial discharge (PD) under repetitive bipolar impulse voltage. Using different waveforms of square voltages, PD inception and elimination voltages (PDIV/PDEV) have been investigated in detail on 50 /spl mu/m air gap between J-shaped enameled wire and plane electrode with polyimide fi…
Insulation degradation mechanism and identification of defect types for cross-linked polyethylene (XLPE) cable and joint have not been cleared yet. Measurement of partial discharge (PD) is one of the most important things of testing the high voltage cable. In this paper, we investigated PD characteristics measured for…
This paper deals with the effect of humidity on Partial Discharge (PD) characteristics in a void with insulation-insulation configuration. The PD patterns were measured using the CIGRE Method-II specimen with various levels of relative humidity. Using the same experimental setup, the statistical time lag was also meas…
A testing apparatus for voltage endurance of film materials subjected to partial discharges on its surface was developed according to IEC-343 and ASTM-2275. It consists of electrode unit, power supply unit and control unit, and has the function of testing simultaneously six group samples. The single chip computer is u…