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Isolation transformer

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


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Journal ArticleDOI
TL;DR: In this paper, the results of an extended series of thermal tests on a variety of dry-type transformer coils are given in regard to the effect of different heights of coil stacks, different configurations, and essential precautions in making temperature measurements are pointed out.
Abstract: With the increasing use of dry-type transformers, attention has been focused upon the fact that the difference between the average temperature rise by resistance and the hottest-spot temperature rise is much greater than in liquid-immersed transformers. In this paper there are given the results of an extended series of thermal tests on a variety of dry-type transformer coils. Data are presented in regard to the effect of different heights of coil stacks, different configurations, and, in addition, some essential precautions in making temperature measurements are pointed out. Hot-spot temperatures were investigated in coils cooled by natural draft and by forced-air circulation at different velocities for both directed flow and random flow. Sufficient data are given to determine the ratio between the average temperature rise of the windings and the hottest-spot temperature rise. Based upon this relationship, the need is shown for review and modification of the conventional hot-spot allowances for dry-type transformers.

20 citations

Journal ArticleDOI
TL;DR: An iron loss calculation method based on the improved generalized Steinmetz equation (iGSE) is presented and a loss separation procedure for the iron loss in the MF transformer and inductors is presented.
Abstract: Recently, because of research and development into SiC power devices, power converter circuits such as high-power isolated DC-DC converters (dual active bridge) using medium-frequency (MF) transformers have been proposed. The converter circuit requires the MF transformer and inductors, but these magnetic components dominate the volume of the circuit. To realize a high-power-density isolated DC-DC converter, it is necessary to analyze the losses in the MF transformer and inductors. In this paper, an iron loss calculation method based on the improved generalized Steinmetz equation (iGSE) is presented. To analyze the iron loss in detail, an analysis method which divides the iron loss into the hysteresis loss and the eddy-current loss is also presented. Further, this paper presents a loss separation procedure for the iron loss in the MF transformer and inductors. In this analysis, the iron loss analysis is performed for different operation modes of the DC-DC converter. Finally, the validity of the separation procedure is confirmed by both analytical and experimental results.

20 citations

Patent
28 Mar 2005
TL;DR: In this paper, a transformer interface was proposed to prevent false ground fault interrupt in a power supply arrangement, where a ground wire current sensor transformer winding is coupled to the ground wire.
Abstract: A transformer interface prevents a false ground fault interrupt in a power supply arrangement. The power supply arrangement has a line wire and a neutral wire connected by way of a ground fault interrupt circuit to an electrically powered device, to which a ground wire is also coupled. The interface has current imbalance sensor transformer windings coupled to the line and neutral wires. A ground wire current sensor transformer winding is coupled to the ground wire. A detector transformer winding produces a signal that triggers operation of the ground fault interrupt circuit, in response to the difference between currents produced by the current imbalance sensor transformer windings exceeding detected ground wire current by a prescribed value.

20 citations

Patent
Wanleng Ang1
22 Jul 2010
TL;DR: In this article, a charger (200) electrically charges a main battery via an electric power conversion path extending through an isolation transformer (260) and providing electrical isolation between an external power supply (400) and the main battery when first and second relays (RL1, RL2) are turned off and a relay (RL3) is turned on.
Abstract: A charger (200) electrically charges a main battery via (10) an electric power conversion path extending through an isolation transformer (260) and providing electrical isolation between an external power supply (400) and the main battery (10) when first and second relays (RL1, RL2) are turned off and a relay (RL3) is turned on. In contrast, the charger (200) electrically charges the main battery (10) via an electric power conversion path bypassing the isolation transformer (260) and providing electrical connection between the external power supply (400) and the main battery (10) when the first and second relays (RL1, RL2) are turned on and the third relay (RL3) is turned off. The charger (200) can thus selectively apply employing the isolation transformer (260) to ensure electrical isolation in externally electrically charging the battery, and bypassing the isolation transformer (260) to give priority to high efficiency in externally electrically charging the battery, as the relays (RL1-RL3) are turned on/off as controlled.

20 citations

Patent
10 Nov 1977
TL;DR: In this paper, the high voltage transformer for the ignition system of an oil burner and the control system for the oil burner are packaged together in a single housing, and the transformer core is of symmetric U-I configuration but the coil arrangement is asymmetric with a single primary coil being provided.
Abstract: The high voltage transformer for the ignition system of an oil burner and the control system for the oil burner are packaged together in a single housing. The duty cycle of the transformer is discontinuous. The transformer core is of symmetric U-I configuration but the coil arrangement is asymmetric with a single primary coil being provided. The transformer is not potted, the core ends are free of coils, and one core end overlaps a circuit board for the control system to thereby foreshorten the overall package. Although the transformer is not potted, tight constraints against shorting of the high voltage secondary leads are maintained by provision of an insulator bushing means which is positioned in apposition to the transformer secondary coils by means of a bracket which also provides a mounting for the transformer core, the high voltage leads being drawn through the insulator bushing means and secured at terminal contacts at the lower ends of the bushing means. The entire package is hinged for movement into and out of working association with the ignition leads of an oil burner.

20 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202313
202251
202144
2020151
2019211
2018266