Improved Insulation Durability to Improve Transformer Aging

Abstract

In transformers, in addition to the primary and secondary coils, there are several other important components and accessories in which the insulating material is one of the most critical components of a transformer. Sufficient insulation between different active parts are necessary for safe operation. Adequate insulation, it is not only necessary to insulate the coils from each other, or from the core and tank, but also guarantees the safety of the transformer against accidental surges, but with the growth in size and complexity of power stations, transformer is facing insulation problems. The evaluation of the transformer overload capacities certainly leads to complex variables that affect the operating life of the power and distribution transformer. In this study, the long-life calculation is performed on the basis of two experiments, which are related to the insulation degradation of the mineral oil and cellulose paper such as by adding different types of nano-particles to the mineral oil to enhance the strength of oil, and by changing the loads under different operating conditions to control the deteriorating rate of the insulation to prevent the life of the transformer. The insulation breakdown strength is improved from 37 kV to 71 kV by mixing the semiconductor nanoparticles such as gadolinium-doped ceria (GDC) and cerium dioxide (CeO2) with mineral oil. Moreover, for cellulose paper, thermal degradation rate is kept below its limit by reducing the temperature when controlling the load.

Prognostication of Failures Using Signal-to-Noise Ratio to Determine Partial Discharges Activities in Power Transformers

“…As seen in Fig. (6) there is no PD activity at the rated voltage of the coil applied for 5 hours and the entire graph simply consists of spikes that are probably due to small electromagnetic noise present in the environment and noise picked up within the measuring circuit. Moreover, the very small amount of noise detected may perhaps also be due to slight corona that may occur inside the tank as the distance of coil from the walls of the enclosure tank was less than that in actual transformer assembly.…”

“…Throughout its service life, a transformer is under the influence of cyclic chem-ical, electrical, thermal, mechanical, and electromagnetic stresses during normal and ab-normal load conditions [4]. The transformer insulation is subjected to different stresses and degrades gradually during operation, depending on the duration and magnitude of overvoltage which results in the core overheating and overstressing the insulation [5,6]. Sometimes, poor insulation design and the use of sub-standard materials results in localized over-heating due to corona type discharges [7].…”

Effect of Impregnated Phenolic Resins on the Cellulose Membrane for Polymeric Insulator

“…Polymers, such as ethylene propylene rubber (EPR) [1], ethylene propylene diene methylene (EPDM) [2], silicon rubber [3], paper [4], and thermoset resins, such as phenolic resin (PF) [5], are commonly used for electrical insulation, in addition to glass and ceramic. The polymer electrical insulator is widely used in electronic packaging [6], thermal management [7], high-voltage systems [8], coating [9], distribution lines [10], etc.…”

Analysis of Polarization and Depolarization Currents of Samples of NOMEX®910 Cellulose–Aramid Insulation Impregnated with Mineral Oil

“…Particularly for new power transformers, the technical condition of the electric insulation saturated with dielectric fluids is regarded as the basic hazard to safe operation, where the key factors are the level of moisture as well as the degree of ageing, defined as the degree of the materials' thermal degradation [1][2][3][4][5][6]. Despite decades of designing and manufacturing power transformers, cellulose electric paper saturated with insulating mineral oil continues to be used as the basic electric insulation system.…”