Insulator (electricity)

About: Insulator (electricity) is a research topic. Over the lifetime, 15941 publications have been published within this topic receiving 108950 citations. The topic is also known as: electrical insulator.

Fiber optic voltage sensor for 420 kV electric power systems

Abstract: We present an optical fiber voltage sensor for 420 kV electric power lines. The sensor exploits the converse piezoelectric effect of quartz and measures the voltage by a line integration of the electric field. The alternating voltage is partitioned to a series of four cylinder-shaped quartz crystals, which are embedded in polyurethane resin within a 3.2-m long insulator tube of fiber reenforced epoxy. The alternating piezoelectric deformations of the crystals are sensed by a common elliptical-core dual-mode fiber, which is wound onto the circumferential crystal surfaces. The fiber is interrogated using low coherence interferometry. We determine the dielectric design of the sensor from a numerical analysis of the electric field distribution within and in the vicinity of the sensor. We experimentally verify the dielectric reliability under ac overvoltages up to 520 kV root mean square (rms) and lightning and switching impulse voltages up to 1425 and 1050 kV, respectively. Further, we investigate the sensor performance including accuracy, dynamic range, bandwidth, and temperature dependence.

Experimental Study of Current Discharge Behavior and Hard X-ray Anisotropy by APF Plasma Focus Device

Abstract: Amirkabir (APF) is a new Mather-type plasma focus device (16 kV, 36 μf, and 115 nH). In this work we present some experimental results as variation of discharge current signal respect to applied voltage at the optimum pressure, focusing time of plasma versus gas pressure, and variations of current discharge with different insulator sleeve dimensions. As we prospected optimum pressure tending to increase as we tried to higher voltage levels. The time taken by the current sheath to lift-off the insulator surface and therefore quality of pinched plasma depends on the length of the insulator sleeve. The results show that the insulator diameter can influence on pinch quality. Behavior of hard X-ray (HXR) signals with the pressure and also anisotropy of HXR investigated by the use of two scintillation detectors. The distribution of HXR intensity shows a large anisotropy with a maximum intensity between 22.5° and 45° and also between −22.5° and −67.5°.

Graded or stepped energy band‐gap‐insulator MIS structures (GI‐MIS or SI‐MIS)

Abstract: A new concept in nonvolatile semiconductor memory using graded or stepped energy band‐gap insulators under the gate electrode of a metal‐insulator‐semiconductor type structure is described. With the graded or stepped insulator, electrons or holes can be injected from the gate electrode at low to moderate applied fields. These carriers then flow under the applied voltage bias into a wide energy band‐gap insulator (such as SiO2) with a purposely introduced charge trapping layer (such as ion‐implanted As, deposited W, or deposited polycrystalline Si). This trapping layer captures and stores electrons (’’write’’ operation) or holes (’’erase’’ operation) with as close to 100% efficiency as possible. Because of the larger energy barriers at the semiconductor (such as Si) interface with the wide energy band‐gap insulator (such as SiO2), few carriers of the opposite sign are injected. Therefore, the substrate Si‐SiO2 interface, for instance, can be used strictly for charge sensing (’’read’’ operation) such as in ...

Electric-Field Limits for the Design of Grading Rings for Composite Line Insulators

Abstract: A major consideration for utilities applying composite insulators on overhead lines and substations is the aging of the polymer materials used for insulator housing. Historically, a primary driver for composite insulator development was to achieve a good contamination of flashover and aging performance. However, the application of composite insulators is not only limited to highly contaminated areas since large numbers are now also installed in locations with low contamination severities. The study of the long-term aging and life expectancy of composite insulators in clean environments is, therefore, of fundamental importance. Recent work at the Electric Power Research Institute (EPRI) and STRI has identified water-induced discharge activity as an important aging mechanism in these environments. This paper summarizes the findings of the extensive research carried out by these two organizations to determine a practical limit for the permissible E-field on insulator surfaces for design purposes. The initial work by the EPRI to determine e-field thresholds for water-induced corona, published in 1999, is expanded on the basis of small- and full-scale tests by both organizations to refine threshold levels and determine the influence of insulator parameters, such as hydrophobicity and shed profile. The influence of water-induced corona on the aging performance of insulators is also investigated on the basis of in-service inspections, accelerated aging tests, and natural exposure tests. The implications of this work on the need and dimensioning procedures for grading rings are also discussed.