Pressboard

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

Research on return voltage method to diagnose insulation moisture in transformer

Abstract: Moisture in power transformer strongly influences the dielectric properties of oil-paper insulation system. The insulation paper gradually degrades over time, therefore, it is imperative to assess integral condition of oil-paper insulation for assuring a normal operation of power transformers. As a non-destructive diagnostic technique, return voltage measurement is an effective assessment method of water content in transformer pressboard. The study presented in this paper aims of further investigating the reliability of the quantification of water content using dominant time constant in transformer pressboard. Field tests performed on several transformers in different status have shown that the return voltage measurement method can estimate the moisture content in paper insulation of power transformers effectively.

Effect of Non-conducting Particle in Transformer Oil Partial Discharge Characteristics

Abstract: This paper investigates, the effect of non-conducting particle in transformer oil partial discharge (PD) characteristics with quasi-uniform field under applied AC voltage. Non-conducting particle such as cellulose fibre from paper or pressboard were used to study the PD characteristics. The cellulose fibre is hydroscopic and absorbs water very quickly. The cellulose fibre having very high affinity to draw water from oil at room temperature. Once the cellulose fibre become wet, the conductivity and permittivity may increase, it can significantly affect the insulation performance of the oil. Dryness of the cellulose fibre greatly depend on the temperature and drying condition. Therefore the cellulose fibre from pressboard dried in an oven at temperature of 105 °C for 1 h, 2 h, 4 h and 6 h were used to study the effect of cellulose fibre in oil with different dry conditions. The cellulose fibre without drying is also used to study the wet condition. PD detection according to IEC 60270 was employed to understand the effect of non-conducting particle on transformer oil PD characteristics under quasi-uniform field. The phase resolved PD (PRPD) pattern, PD characteristics such as magnitude, number, discharge power, rise and duration time were analysed. The observed PRPD pattern began from 45o and 225o phase of applied AC cycle, further increase of voltage can enhance the appearance of PD throughout the phase, and patterns are similar trend regardless of the wet conditions of cellulose fibre. The observed PDIV is close for each dry conditions of cellulose fibre whereas discharge magnitude has significant variation.

Compound hot pressboard for hot press

Abstract: The utility model discloses a compound hot pressboard for a hot press. The compound hot pressboard for the hot press comprises the hot pressboard with an upper working plane and a lower working plane, wherein the upper working plane and the lower working plane of the hot pressboard are provided with a flexible buffer layer in a pasting mode, the external surface of the flexible buffer layer is provided with a stainless steel plate, and the stainless steel plate tightly wraps up the hot pressboard covered with the flexible buffer layer. The compound hot pressboard for the hot press is capable of meeting the requirement that veneer, micro-veneer and decorative paper are pasted on an artificial board with basic material which are high in density, strong in intensity and poor in surface flatness, and quality of attaching veneer is improved.

Modeling of Ion Injection in Oil-Pressboard Insulation Systems

Abstract: To make a High Voltage Direct Current (HVDC) transmission more energy efficient, the voltage of the system has to be increased. To allow for that the components of the system must be constructed to ...