The main problem in power transformers is the degradation of the isolation, and partial discharges are a major contribution to this shortcoming. Partial discharges inside mediumand high-power transformers generate ultrasonic pressure waves which are usually detected by using acoustic piezoelectric sensors placed outside the transformers. In this paper we describe an optical fibre interferometri...

This paper reports on the results of recent research and development efforts to study and assess various impacts of ferroresonance phenomenon on operating performance of power transformers and to investigate ways to mitigate the effects of such phenomenon. Three-phase core-type transformers are used in the study. The results of the technical investigation and the associated ferroresonance exper...

Prediction of the remaining life of high-voltage power transformers is an important issue for energy companies because of the need for planning maintenance and capital expenditures. Lifetime data for such transformers are complicated because transformer lifetimes can extend over many decades and transformer designs and manufacturing practices have evolved. We were asked to develop statistically...

Economically transformers constitute one of the largest investments in a Power system. For this reason, transformer condition assessment and management is a high priority task. If a transformer fails, it would have a significant negative impact on revenue and service reliability. Monitoring the state of health of power transformers has traditionally been carried out using laboratory Dissolved G...

The development of electrical railway systems leads to critical power quality problems in the power grid. This paper discusses a kind of half-bridge-based railway power quality compensator system (HBRPQC) that can compensate negative sequence currents, harmonics, and reactive power simultaneously. In order to keep the HBRPQC performance efficient for the different kinds of transformers used in ...

This paper presents the effects of instrument transformers connection points on the measured impedance by distance relays in the presence of Flexible Alternating Current Transmission System (FACTS) devices with series connected branch. Distance relay tripping characteristic itself depends on the power system structural conditions, pre-fault operational conditions, and especially the ground ...

As an integral part of the Smart Grid, smart transformers both work independently to constantly regulate voltage and maintain contact with the smart grid in order to allow remote administration if needed and to provide information and feedback about the power supply and the transformers themselves. Through a process known as voltage optimization, a smart transformer provides the exact amount of...

Usually, harmonics are the base point when engineers start to analyze waveform distortion. Frequencies of these voltage and current waveforms are integer multipliers of the base frequency of power system (50 Hz or 60 Hz). If it is not the case then these are named as intermediate harmonics. The sinusoidal waveforms of voltage characterize the ideal power system with the highest clarity of base ...

The successful realization of a project for slitting core laminations for power transformers under minimizing costs is presented. The production of the core of power transformers requires great amounts of grain oriented silicon steel (up to 200 tons for a single transformer). The shape of the cross section of the core is approximated to a circle by stacking sheets of diierent widths. To supply ...