The most important parameter in transformers life expectancy is the hot-spot temperature level which accelerates the rate of aging of the insulation. The aim of this paper is to present thermal models for transformers loaded at prefabricated MV/LV transformer substations and outdoor situations. The hot-spot temperature of transformers is studied using their top-oil temperature rise models. The ...

The breakdown voltage of mineral insulation oil was systematically investigated under the influences of moisture, acidity, pressure and particles. The standards IEC156/95 (VDE0370/Part5/96 and ASTM D1816) specified the test conditions. Moisture provides charge carriers, therefore a moisture saturation of 0 to 20 % decreases the breakdown voltage from 72 down to 61 kV. Acids as aging products de...

Power systems and transformer are intrinsic apparatus, therefore its reliability and safe operation is important to determine their operation conditions, and the industry uses quality control tests in the insulation design of oil filled transformers. Hence the service period effect on AC dielectric strength is significant. The effect of aging on transformer oil physical, chemical and electrical...

The thermal conductivity of three mixtures of nitrogen and cyclopentane is measured using a transient hot wire method, at temperatures between 315.14 and 395.89K, and pressures up to 0.53MPa. These mixtures are important in the evaluation of the evolution of the thermal insulation capacity of closed-cell polyurethane foams considering their aging during the respective applications’ total life t...

Transformers are the basic and valuable equipment of electricity network. Transformers correct function has important role in reliability of network .distribution transformers are designed for work at nominal frequency and full sinus current. Application of nonlinear loads in recent decades, such as power electronic loads, caused higher levels of harmonic. This kind of load can lead to creating...

The increasing energy consumption levels of buildings within Europe call for controlled and improvements to savings efficiency effective regulations. However, many aging energy-inefficient require energetic retrofitting that can employ various façades solutions insulation materials. selection the most sustainable options in each situation therefore requires a decision-making methodology be used...

Transformers play a crucial role in power systems. In this respect, fault diagnosis and aging state assessment have garnered significant attention from researchers. Herein, accelerated thermal Raman scattering experiments are conducted on oil–paper insulation samples to accurately detect states. The categorized into different stages based the polymerization degree of insulating paper. Principal...