Isolation transformer

About: Isolation transformer is a research topic. Over the lifetime, 8145 publications have been published within this topic receiving 72396 citations.

The influence of square voltage waveforms on transformer insulation break down voltage

Abstract: The use of Voltage Source Converters (VSCs) in HVDC transmission and, more generally, in flexible AC transmission systems (FACTS), raises concerns over the endurance of turn/turn insulation of grid/converter interface transformers. In this paper, tests performed on oil-impregnated paper specimens are discussed. The results indicate clearly that shorter rise times and higher repetition frequencies have a strong impact on both partial discharge inception voltage and breakdown voltage. These results suggest that deeper investigation might be important to understand the long term behavior of these insulation systems.

ZVS Converter With Parallel Connection in Primary Side and Series Connection in Secondary Side

Abstract: This paper presents an active snubber dc/dc converter to realize the zero voltage switching of power switches. Thus, the switching losses on power switches can be reduced. The primary windings of two transformers are connected in parallel to reduce the transformer current stresses. To reduce the transformer secondary winding turns at high-output-voltage applications and distribute output power to two transformers, two transformer secondary windings are connected in series. Thus, the transformer primary currents are automatically balanced. A full-wave diode rectifier is used at the secondary side to realize full-wave rectification at the output side and reduce voltage stress on rectifier diodes. Finally, the performance of the proposed converter is evaluated on a 600-W (400 V/1.5 A) laboratory prototype.

Primary adjusted switched-mode power supply

Abstract: In order to adjust the output voltage and output current of a galvanically isolated switched-mode power supply, on the primary side there is formed an auxiliary voltage (15) proportional to the secondary voltage, and said auxiliary voltage is studied by means of a window comparator, so that when the auxiliary voltage is within the reference window, there is applied fixed power adjustment, and when the auxiliary voltage falls outside the reference window (>max,

Localising low-level short-circuit faults on the windings of power transformers based on low-frequency response measurement of the transformer windings

Abstract: Early detection and localisation of winding faults within the transformer can help make preventive actions and reduce potential damages to the transformer and the power system. This research work presents a new technique for sensitive detection and localisation of shorted turns on the windings of power transformers throughout low-frequency response measurements of the transformer windings. To this end, using genetic algorithm, the detailed model of the damaged winding by the fault is estimated from the measured low-frequency response data up to 10 kHz. The fault is localised along the winding by establishing the differences between the transfer functions of the healthy and faulty state of the winding units using statistical indicators. The experimental measurements which were made on a test transformer damaged by a low-level short-circuit fault proved that the newly developed method is sufficiently able and sensitive to detect and localise failures of only few shorted turns on the transformer windings.

Effect of power system harmonic on degradation process of transformer insulation system

Abstract: Harmonic is one of common phenomenon occurred during power system operation, especially when the non linear load applied within the power system. These harmonic will affect to the transformer, such as increasing hysteresis losses (magnetization) on steel and iron of transformer core, where the value is temperature depended. Degradation of transformer insulation can be driven by this temperature increasing. The harmonic that monitored continuously can be use as a reference parameter of degradation level of transformer insulation. To determine the actual condition of transformer insulation we developed Dissolved Gas Analysis (DGA) to enrich data analysis and using power quality monitoring to determine the power condition. This paper will discuss the possibility effect of harmonic phenomenon due to degradation process of transformer insulation system based on DGA and power quality analysis.