Pressboard

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

Improved generation heat supply system for multilayer hot pressing trigger

Abstract: The utility model discloses an improved generation heat supply system for multilayer hot pressing trigger, including the frame body, this frame body superimposition erects the hot pressboard that a plurality of layers are hollow structure, be equipped with the elastic connection component between the two adjacent hot pressboards, the both sides of hot pressboard are connected respectively and are equipped with a heating device, these two heating device are linked together through this hollow structure's hot pressboard, heating device includes that the heat carries the body and be used for connecting the body of being connected that body and hot pressboard were carried to the heat, a plurality of heat output mouth has been laid on the heat transport body, and the heat is carried the one end of body and is provided thermal vapours source and is linked together. The utility model discloses not only can improve thermal conveying speed, can make in addition on the heat transmits the hot pressboard sooner more uniformly, improve the effect of solidifying of glue, the quality that makes the plywood obtains more that furtherly improves.

Analysis of incipient discharge activity in nano particles dispersed ester oil insulation

Abstract: In recent times, ester oil is used as insulation in transformers. In order to improve the performance characteristics, silicondioxide nano particles were dispersed in the oil. An attempt has been made to understand the corona activity under high frequency AC and harmonic AC voltages with different level of distortion. No characteristic variation in corona inception voltage is observed with increase in supply voltage frequency. The UHF signal formed during corona discharge activity has dominant frequency at near 1 GHz An attempt has been made to understand the surface charge accumulation characteristics of paper insulation impregnated in nano particle dispersed ester oil. It is observed that in paper insulation in nano ester oil, the initial charge accumulation is low. Phase resolved PD analysis was carried out to understand corona activity in ester oil and nano particle dispersed ester oil, under AC and harmonic AC voltages. Fourier Transform Infrared spectroscopy (FTIR) analysis was carried out in order to quantify effect of nano particles on surface characteristics of oil impregnated pressboard (OIP) sample.

Non-power supply thermal compressor

Abstract: The utility model relates to a device which presses, levels or adhibits a working face by use of heat quantity from fuel combustion in a combustion chamber (3) of hot-pressing device via a heat-conducting hot pressboard (2) of heat-conducting board in case of no power supply. The device is composed of a hot pressboard (2) which is connected with a combustion chamber (3), a top cover (4), a switch (5), a support (6) and a handle. The utility model can be operated without power and is carried conveniently.

Applying HF and VHF/UHF Partial Discharge Detection for Distribution Transformer

Abstract: This paper represents application of high frequency (HF) and very high frequency/ultrahigh frequency (VHF/UHF) partial discharge (PD) detection for a distribution transformer. A capacitive sensor is used to detect the HF electric field caused by charge transfer inside oil–paper insulation due to PD at the defect site, and an electromagnetic sensor or antenna is used for detecting electromagnetic PD transients in the air outside the investigated transformer in the near-field region. Three types of artificial PD sources in air and insulating liquid, which are corona discharge, surface discharge and air void discharge in pressboard, were investigated. Three identical distribution transformers were rated at 22 kV, 400 V and 50 kVA, and were designed and constructed. The first transformer was filled with mineral oil, the second was filled with natural ester and the third was filled with palm oil. The PD generated by the air-filled voids in the insulating papers and pressboards of these transformers with five different conditions were investigated, i.e., non-impregnated paper, impregnated paper for 3 hours, 6 hours, 9 hours and 12 hours. The impregnation process was done with 65°C liquid temperature, and the pressure in the oven was around 5 mbar. From the experimental results, it can be concluded that the electromagnetic PD transients radiated from the corona discharge of both high-voltage (HV) and low-voltage sides in the air are in the VHF range, and surface discharge frequency is extended up to the UHF range. For the PD in the insulating liquid, the phase resolved PD (PRPD) pattern in the HF range is a valuable tool to characterize the PD sources. The PD in an air-filled void inside the insulating paper of the mineral oil transformer is obviously different compared with those of the natural ester transformer and the palm oil transformer. For the manufacturing of distribution transformers in this research, it is found that after the paper insulation is dried out, the impregnation process for a period of 9 hours is suitable for improving the oil–paper insulation with an acceptable PD level. This paper is the cross-field application by applying the antenna and communication theory for detecting the discharge problems in HV equipment.