Pressboard

About: Pressboard is a research topic. Over the lifetime, 1123 publications have been published within this topic receiving 9089 citations.

Understanding surface discharge activity in copper sulphide diffused transformer insulation under harmonic AC voltages

Abstract: In the present study, the surface discharge injected current were measured by using High Frequency Current Transformer (HFCT) It is observed that the rise time of the current pulse is about 800 ps It is confirmed that the injected current pulse radiates Ultra High Frequency (UHF) signal and the dominant frequency of the UHF signal formed due to the surface discharge injected current is about 09 GHz The characteristic frequency contents of the UHF signal formed due to surface discharge activity is the same with the virgin and copper sulphide diffused pressboard material The Atomic Absorption Spectroscopy (AAS) results indicate that the amount of copper content in pressboard material have increased with the increase in the concentration of Dibenzyl disulphide (DBDS) in transformer oil The Phase Resolved Partial Discharge (PRPD) analysis indicates that at the point of surface discharge inception, the discharge occurs at the peak of the applied AC voltage and when the applied voltage magnitude is increased the discharge occurs at the rising portion of the applied AC voltage It is noticed that with increase in DBDS concentration, there exists an increase in the discharges

Analysis of Discharge Image and Particle Characteristics of Needle Plate in Transformer Oil Under AC Voltage

Abstract: For the development of converter transformer applications, research on the discharge characteristics in transformer oil is required. This article presents an analysis of the streamer discharge characteristics caused by a needle-plate electrode in oil-pressboard insulation under ac voltage and discharge images on the time scale of microseconds. Based on the discharge image, a Gaussian filter, image segmentation of the Otsu algorithm, and Canny edge detection are used to detect the edge of the discharge image. By extracting the discharge profile image, the discharge characteristics are effectively identified. The size and quantity of particles in transformer oil during the discharge are analyzed. Research on the characteristics of streamer discharge propagation is not only helpful for understanding the process of discharge but also has important significance for converter transformer design from the perspective of inhibiting streamer discharge.

Experimental Study on Bubble Effect of Oil–Paper Insulation in Natural Ester

Abstract: The rapid temperature rise brought by short-term overload may cause the oil–paper insulation of transformer to produce bubbles. The existence of bubbles will reduce the electrical strength of transformer insulation and may lead to partial discharge or even breakdown of the oil–paper insulation in the transformer. In this article, the bubble effect of oil–paper insulation in natural ester is studied experimentally. A bubble effect test platform is designed and built according to the temperature conditions of the transformer in operation, and bubbling tests are carried out for natural ester-cellulose insulation. Initial temperature of bubble escape (ITBE) is obtained for different winding insulation paper layers, temperature rise rate, and pressboard aging time, respectively. The experimental results show that the bubbles aggregate in the gap between the paper layers before bubbles escape into oil, and ITBE is affected by winding insulation paper layers. Besides, a higher temperature rise rate corresponds to a lower ITBE. With the thermal aging of pressboard, ITBE increases, because the number and diameter of pores decrease in fibers of pressboard.

Secondary low-gas-emission chemical power supply

Abstract: electrical engineering; secondary power supplies and electrochemical aqueous-electrolyte capacitors. SUBSTANCE: power supply (it may be nickel-cadmium, nickel-iron, nickel-metal-hydride, or lead storage cell) has its auxiliary electrode manufactured from material made of activated carbon fibers and placed between separator and negative electrode; it is mounted on negative-electrode surface; size of most pores of auxiliary electrode is greater than that of most separator pores. Auxiliary electrode may be made in the form of fabric or non- woven material, pressboard, or paper. It may be placed on one or both sides of negative-electrode plates. Total volume of electrolyte in pores of separator and electrodes is smaller than total volume of their pores. EFFECT: reduced gas-emission level in the course of charge; reduced electrolyte level check and replenishment intervals. 5 cl, 2 dwg