Papers by Sheshakamal Jayaram
[Proceedings] 1992 Annual Report: Conference on Electrical Insulation and Dielectric Phenomena
ABSTRACT Inactivation of Lactobacillus brevis cells in suspensions of phosphate buffer solutions ... more ABSTRACT Inactivation of Lactobacillus brevis cells in suspensions of phosphate buffer solutions of different conductivities (170 μS/cm to 2230 μS/cm) using electric pulse application has been investigated. Survivability as a function of pulse application number has shown a logarithmic death for all test conditions. A maximum reduction in survivability was obtained in low-conductivity liquid medium. The pulse energy influences the survival rate of L . brevis cells by altering the liquid temperature during pulse discharge; however, the direct lethal effect of heating was insignificant as the maximum temperature rise was only 22°C upon application of 600 pulses of 8 W-s/pulse
Conference Record of the 1991 IEEE Industry Applications Society Annual Meeting
1991 Annual Report. Conference on Electrical Insulation and Dielectric Phenomena,
The paper reports the results of a study of charge separation J by forcing low conductivity liqui... more The paper reports the results of a study of charge separation J by forcing low conductivity liquids through micro-pore f different types and pore sizes. The influence of filtration on 4 tendency of the test liquids has been studied for a range of f l i and temperatures. The cellulose acetate cellulose nitrate Millipo charged the oila positively, while glass fibre Sartorius pre filters the oils negatively. The charging tendency of Norpar 15 d when the flow rate was-> 6 x lo6 m31s). Based on the expel results it is propocred that the charge content of the oil can be re forcing the oil through defined micro-pore structure 01 composition and by allowing the charged oil to relax electric relaxation chamber.
IEEE Transactions on Power Delivery, 2007
One of the most important factors in an artificial pollution test of transmission and distributio... more One of the most important factors in an artificial pollution test of transmission and distribution insulators of power systems is the short-circuit current of the source. Most laboratories do not have strong source and test transformers. In this paper a test setup has been introduced to improve the performance of high-voltage laboratories for pollution test. It is based on adding
International Journal of Emerging Electric Power Systems, 2008
This paper presents the results of an investigation on evaluating room-temperature-vulcanized (RT... more This paper presents the results of an investigation on evaluating room-temperature-vulcanized (RTV) silicone rubber coatings for high-voltage insulators of substations and overhead transmission lines. It is based on tests conducted for three different available RTVs that are currently used by utilities. The study compared three commercial coatings: RTV-A and RTV-B filled with ATH (aluminum tri-hydrate) as the primary filler, and RTV-C filled with silica. The relative comparison between them is based on their electrical and chemical characteristics. The evaluation employed standard and research-based evaluation methods, including the salt fog test, the inclined plane test, thermo-gravimetric analyses (TGA), thermal conductivity measurement, soaking in water, the mechanical test, and SEM photographs. Results of the inclined plane test showed that the silica-filled coating is not resistive against tracking and erosion compared with ATH-filled coatings. It was observed that filler size ...
IEEE Transactions on Industry Applications, 2008
ABSTRACT Variable-speed pulsewidth-modulated (PWM) drives allow for precise speed control of indu... more ABSTRACT Variable-speed pulsewidth-modulated (PWM) drives allow for precise speed control of induction motors, as well as a high power factor and fast response characteristics, compared with nonelectronic speed controllers. However, due to the high switching frequencies and the high dV/dt, there are increased dielectric stresses in the insulation system of the motor, leading to premature failure, in high power and medium- and high-voltage motors. Studying the degradation mechanism of these insulation systems on an actual motor is both extremely costly and impractical. In addition, to replicate the aging process, the same waveform that the motor is subjected to should be applied to the test samples. As a result, a low-power two-level high-voltage PWM inverter has been built to replicate the voltage waveforms for aging processes. This generator allows for testing the insulation systems considering a real PWM waveform in which both the fast pulses and the fundamental low frequency are included. The results show that the effects of PWM waveforms cannot be entirely replicated by a unipolar pulse generator.
Electric Power Systems Research, 2017
As an extensive network of resistances, capacitances, and inductances, a transformer has inherent... more As an extensive network of resistances, capacitances, and inductances, a transformer has inherent characteristic parameters that are functions of frequency. The form of these functions is predicated on the geometric design of the transformer and materials that comprise it. Any change in the structure of a transformer will be reflected in its frequency response characteristics. Of the possible changes that can take place in a transformer structure, an internal short circuit is one of the far-reaching incidents that has been recently reported for many wind-farm transformers. Detecting the location of an internal short circuit that has occurred in a transformer winding is therefore beneficial in the repair process and also in improving future designs. In an effort to identify trends with inter-turn fault locations and frequency responses, this research investigates the effect of the location of deliberately initiated internal faults on parameters such as transfer voltages and input impedances by means of sweep frequency response analysis (SFRA). The analysis of three different model transformers with different core and winding designs shows several trends in frequency response patterns, depending on the location of the internal short circuits. The paper discusses such trends as a potential use of SFRA in locating inter-turn winding failures that may result in noticeable short circuits.
2013 IEEE Electrical Insulation Conference (EIC), 2013
ABSTRACT
CEIDP '05. 2005 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, 2005., 2005
... Majid Sanaye-Pasand 2 Hosein Mohseni2 1 ECE Department, University of Waterloo,Ontario, Canad... more ... Majid Sanaye-Pasand 2 Hosein Mohseni2 1 ECE Department, University of Waterloo,Ontario, Canada 2ECEDepartment, University of Tehran, Iran ... 7 ° 6 -RTV-BArgin RTV-A ag d 5o ... On the other hand, the 3rd harmonic of RTV-B increased by 11% due to acid aging but the ...
IEEE Transactions on Dielectrics and Electrical Insulation, 2015
The paper reviews previous work on the DC inclined plane test and suggests equivalent DC voltage ... more The paper reviews previous work on the DC inclined plane test and suggests equivalent DC voltage levels in parallel to AC voltage in the ASTM inclined plane tracking and erosion test. The aim of this work is to provide a basis for standardizing the inclined plane test for DC voltage. Round robin tests done in five laboratories on five specimens of a silicone rubber material were done with the purpose of establishing appropriate ratios by which the equivalent DC voltages can be determined with respect to the corresponding AC voltages. These levels were determined as 67% and 87%, for +DC and-DC respectively, of the AC initial tracking voltage.
Electric Power Systems Research, 2017
IEEE Transactions on Power Delivery, 2000
One of the most important factors in an artificial pollution test of transmission and distributio... more One of the most important factors in an artificial pollution test of transmission and distribution insulators of power systems is the short-circuit current of the source. Most laboratories do not have strong source and test transformers. In this paper a test setup has been introduced to improve the performance of high-voltage laboratories for pollution test. It is based on adding
IET Science, Measurement & Technology
This work studies the changes that occur in transformer insulation properties when voltages with ... more This work studies the changes that occur in transformer insulation properties when voltages with steep fronts and high-frequency contents are applied. With a significant growth in the number of wind-farms and solar-plants that use power-electronic-based converters, the problems associated with such voltages on insulation has led to increasing concerns. Distorted voltages accelerate the transformer insulation degradation. Two identical transformers are studied by energizing independently under power frequency sinusoidal and width-modulated pulse trains. The dielectric characteristics of the test objects, like partial discharge activities, insulation resistance, are periodically measured during the ageing process. After a period of 500 hours of testing the dissolved gases are also analyzed. The results for both transformers are compared and discussed.
Conference on Electrical Insulation and Dielectric Phenomena, 1992
The performance of antistatic additives as charge suppressants in the insulating liquid Voltesso ... more The performance of antistatic additives as charge suppressants in the insulating liquid Voltesso 35 has been investigated in a wide range of operating temperatures, 24-105°C. The ionic additive Stadis 450 is found unsuitable as a charge suppressant in transformer oils because of a large increase in the liquid conductivity with as little as 2-5 ppm of Stadis 450 added. The
IEEE Transactions on Dielectrics and Electrical Insulation, 2015
ABSTRACT The paper reviews previous work on the DC inclined plane test and suggests equivalent DC... more ABSTRACT The paper reviews previous work on the DC inclined plane test and suggests equivalent DC voltage levels in parallel to AC voltage in the ASTM inclined plane tracking and erosion test. The aim of this work is to provide a basis for standardizing the inclined plane test for DC voltage. Round robin tests done in five laboratories on five specimens of a silicone rubber material were done with the purpose of establishing appropriate ratios by which the equivalent DC voltages can be determined with respect to the corresponding AC voltages. These levels were determined as 67% and 87%, for +DC and -DC respectively, of the AC initial tracking voltage, and for practical purposes, these levels are rounded to 70 and 90%.
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Papers by Sheshakamal Jayaram