scholarly journals Dual-Temperature Evaluation of a High-Temperature Insulation System for Liquid-Immersed Transformer

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1957 ◽  
Author(s):  
Xiaojing Zhang ◽  
Lu Ren ◽  
Haichuan Yu ◽  
Yang Xu ◽  
Qingquan Lei ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Aging ◽  
Thermal Calculation ◽  
Insulation System ◽  
Dielectric Parameters ◽  
Distribution Transformers ◽  
Aging Test ◽  
Insulation Systems ◽  
Paper Insulation ◽  
Natural Ester

A high-temperature oil–paper insulation system offers an opportunity to improve the overloading capability of distribution transformers facing seasonal load variation. A high-temperature electrical insulation system (EIS) was chosen due to thermal calculation based on a typical loading curve on the China Southern Power Grid. In order to evaluate candidate high-temperature insulation systems, Nomex® T910 (aramid-enhanced cellulose) immersed in FR3 (natural ester) was investigated by a dual-temperature thermal aging test compared with a conventional insulation system, Kraft paper impregnated with mineral oil. Throughout the thermal aging test, mechanical, chemical, and dielectric parameters of both paper and insulating oil were investigated in each aging cycle. The thermal aging results determined that the thermal class of the FR3-T910 insulation system meets the request of overloading transformer needs.

Improvement of High-Temperature Reliability of Ball Bond Using Platinum-Modified Gold Alloy Wires

2007 ◽  
Vol 4 (2) ◽  
pp. 45-50 ◽  
Author(s):  
Kazunari Maki ◽  
Yuji Nakata ◽  
Masayoshi Nagao ◽  
Akifumi Mishima
Keyword(s):  
High Temperature ◽  
Thermal Aging ◽  
Gold Alloy ◽  
Microstructural Analysis ◽  
Ball Bond ◽  
Ball Shear ◽  
Aging Test ◽  
Bond Degradation ◽  
Bonding Wires ◽  
Ball Bonds

For superior Au/Al ball-bond reliability, we have developed the 3N (>99.9 wt% Au), 2N5 (>99.5 wt% Au) and 2N (>99 wt% Au) Au alloy bonding wires which contain less than 0.1, 0.5 and 1 wt% Pt, respectively. In the thermal aging test of squashed balls (40 μm in diameter), which consists of storage in air at 250°C and evaluation with wire pull and ball shear, it has been found that there are interesting differences in the ball-bond degradation as a function of wire type. Even the samples bonded using the 3N wire with a very small amount of Pt show superior ball-bond reliability compared with those using a 4N (>99.99 wt% Au) wire without any addition of Pt. The ball-bond degradation in the thermal aging test is reduced significantly with increasing Pt content of a wire. From microstructural analysis of the aged 2N ball bonds, the Pt-containing layer, which seems to play a crucial role in improvement of the ball-bond reliability, have been found in the upper part of intermetallic compounds.

Behavior of machine insulation systems subjected to accelerated thermal aging test

2010 ◽  
Vol 17 (5) ◽  
pp. 1364-1372 ◽  
Author(s):  
M. Farahani ◽  
E. Gockenbach ◽  
H. Borsi ◽  
K. Schafer ◽  
M. Kaufhold
Keyword(s):  
Thermal Aging ◽  
Aging Test ◽  
Insulation Systems ◽  
Accelerated Thermal Aging

Properties of high temperature resistance and salt tolerance drilling fluids incorporating acrylamide/2-acrylamido-2-methyl-1-propane sulfonic acid/N-vinylpyrrolidone/dimethyl diallyl ammonium chloride quadripolymer as fluid loss additives

2014 ◽  
Vol 34 (2) ◽  
pp. 153-159 ◽  
Author(s):  
Junlin Su ◽  
Qi Chu ◽  
Mao Ren
Keyword(s):  
High Temperature ◽  
Ammonium Chloride ◽  
Thermal Aging ◽  
Sulfonic Acid ◽  
Drilling Fluid ◽  
Gel Permeation Chromatography ◽  
Fluid Loss ◽  
Drilling Fluids ◽  
Aging Test ◽  
Before And After

Abstract A quadripolymer of acrylamide (AM), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS), N-vinylpyrrolidone (NVP) and dimethyl diallyl ammonium chloride (DMDAAC) was synthesized by solution free radical polymerization, and characterized using Fourier transform infrared (FTIR), gel permeation chromatography (GPC) and thermogravimetric analysis (TGA) methods. The rheological and filtrate properties of saturated brine-based fluid with AM/AMPS/NVP/DMDAAC quadripolymer were investigated before and after thermal aging tests. The apparent viscosity (AV), plastic viscosity (PV) and yield point (YP) increased and the filtrate volume decreased with increase in the concentration of AM/AMPS/NVP/DMDAAC quadripolymer after thermal aging test at 180°C for 16 h. The filtrate volume could be controlled when the concentration of AM/AMPS/NVP/DMDAAC quadripolymer reached 2.0% under these conditions. The filtrate volume of saturated brine-based fluid could be controlled effectively at a thermal aging temperature not exceeding 200°C and was smaller than that of the AM/AMPS/NVP terpolymer. The AM/AMPS/NVP/DMDAAC quadripolymer was better at improving the quality of a filter cake than the AM/AMPS/NVP terpolymer. The drilling fluid containing the AM/AMPS/NVP/DMDAAC quadripolymer had an excellent tolerance to salt and high temperature.

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

2020 ◽  
Author(s):  
Sakda Maneerot ◽  
Masaaki Kando ◽  
Norasage Pattanadech
Keyword(s):  
High Frequency ◽  
Partial Discharge ◽  
Mineral Oil ◽  
Surface Discharge ◽  
Distribution Transformer ◽  
Impregnation Process ◽  
Distribution Transformers ◽  
Insulating Liquid ◽  
Paper Insulation ◽  
Natural Ester

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.

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