pulse-width modulated (pwm) adjustable frequency drives (afds) are extensively used in industries for control of induction motors. it has led to significant advantages in terms of the performance, size, and efficiency but the output voltage waveform no longer remains sinusoidal. hence, overshoots, high rate of rise, harmonics and transients are observed in the voltage wave. they increase voltag...

in this study, the effect of wall orientation on the optimum insulation position in the wall from different perspectives is studied numerically. using crank- nicolson one dimensional transient heat conduction equation is solved for the wall with convection boundary conditions. outdoor temperature is considered as a periodic function of time. since natural night ventilation is used in the buildi...

The overall life of oil-immersed power transformers depends on the long-term life of the oil–paper insulation system throughout continuous operation. Studying the reliability assessment methods for oil–paper insulation can help determine the reliability level of power transformers accurately, and ensure their safe and stable operation. In the present paper, the life of oil–paper insulation is p...

Pulse-width modulated (PWM) adjustable frequency drives (AFDs) are extensively used in industries for control of induction motors. It has led to significant advantages in terms of the performance, size, and efficiency but the output voltage waveform no longer remains sinusoidal. Hence, overshoots, high rate of rise, harmonics and transients are observed in the voltage wave. They increase voltag...

In this study, we discuss about the energy saving in different type of building walls by using optimum insulation thickness with suitable insulation material. The energy saving is maintained by reducing the energy consumption in buildings. Heat losses from building envelope have a major share in waste of energy. So it is essential to save the energy by using optimum insulation thickness. The in...

a unique high frequency transient overvoltage surge suppressor for the protection of motors and transformers from steep wave-front, short rise-time, high magnitude, spikes, surges and other transient voltages, generated by switching, lightning and other sources. The protective characteristics of ZORC: Eliminates inter-turn insulation failures Extends the life of machine insulation Eliminates mu...

In this paper, a Markov maintenance model for predicting the remaining life of transformer insulation has been developed. It incorporates various stages of insulation deterioration and minor maintenance state. Given that a current state of insulation ageing has been reached, from a diagnostic testing and inspection, this model is capable of computing the predicted average time before insulation...

To find feasible alternatives to the use of SF6 in medium voltage switchgear equipment, AREVA T&D and Tsinghua University has started a cooperation to investigate the feasibility of using vacuum. This paper focused on three main points of the design of the Vacuum Insulated Switchgear (VIS): the maintainability of vacuum system, the insulation performance, and the thermal behavior under operatin...

The insulation of the high voltage equipment is deteriorated due to the partial discharges (PDs). So it is required to monitor PDs continuously for prediction of insulation life, replacement time and early indication of outages of HV power equipment. In this work, an optical network is used to detect and measure the PDs in a model transformer.