High voltage generators are being subject to higher voltage rating and are being designed to operate in harsh conditions. Stator windings are the main component of generators in which Electrical, magnetically and thermal stresses remain major failures for insulation degradation accelerated aging. A large number of generators failed due to stator winding problems, mainly insulation deterioration...

The main insulation system in high-voltage direct current (HVDC) transformer consists of oil-paper insulation. The formation of space charge in insulation paper is crucial for the dielectric strength. Unfortunately, space charge behavior changes because of the corrosive sulfur substance in oil. This paper presents the space charge behavior in insulation paper induced by copper sulfide generated...

In order to evaluate the reliability of using repulped cellulose in transformers, the aging process was applied on standard and repulped cellulose in a laboratory accelerated model by increasing of temperature to 150 ° C and their behavior was monitored by measuring the amount of 2-furfural released in oil by HPLC (High Performance Liquid Chromatography) in the consecutive aging periods and...

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...

Early detection of avalanche breakdown in an embedded planar capacitor dielectric is addressed in this paper. These failures were observed during accelerated temperature and voltage aging of embedded planar capacitors. At the time of avalanche breakdown there was a sharp drop in the value of insulation resistance. There was no trend in the values of insulation resistance before failure, making ...

Mineral oil is widely being used as insulation for high voltage equipments such as transformer due to its excellent dielectric properties. Recently, due to environment consideration and the long term availability, organic liquid insulations from plantations are being introduced. However, the performance of such insulations in composite with paper should be investigated in order to maintain the ...

Natural esters have become of interest for the industry in recent years as dielectric liquids power transformers, and many studies are focused on their chemical properties influence degradation solid insulation due to aging. However, very little is known about impact evolution mechanical paper insulation, which acknowledged a considerable overall performance reliability during operating life tr...

This paper investigates the morphology, thermal, and electrical properties of LDPE (low-density polyethylene)-based nanocomposites after thermal aging. The FTIR (Fourier transform infrared spectroscopy) spectra results show that thermo-oxidative reactions occur in neat LDPE and LDPE/SiO₂ nanocomposites when the aging time is 35 days and in LDPE/MgO nanocomposites when the aging time is 77 days....

This paper describes the aging behavior of the oil impregnated repulped cellulose and compares it with the aging behavior of the oil impregnated standard cellulose. In order to evaluate the reliability of using repulped cellulose in transformers, the accelerated aging process was applied to both types of cellulose by increasing the temperature to 150 °C and their aging behavior was studied and ...

The oil/paper insulation system in a transformer degrades under various chemical, thermal and electromechanical stresses during its operation. Dielectric response measurements like the Return Voltage Measurement (RVM) and Polarisation and Depolarisation Current (PDC) measurement are currently being used for condition assessment of the insulation. In the current research project, the ageing cond...