Open-delta Transformer Research Articles

PERFORMANCE STUDY OF UNBALANCED LOAD ON OPEN DELTA TRANSFORMERS

A transformer is a device that can transfer (transmit) and change electrical energy from one electrical circuit to another with the same frequency based on the principle of electromagnetic induction. The transformer that will be used in this research is a three-phase open delta connection transformer, which is connected to a delta connected load. If one of the three phase windings in the delta connection transformer is damaged, then the remaining two windings can be implemented or designed into three phase open delta connections, which can be used to distribute three phase electrical power to the load. The performance of the unbalanced load influence on the open delta transformer, when it is loaded with an unbalanced load that is not the same size on each phase, causes an increase in current on each phase, resulting in an increase in the input power absorbed by the unbalanced load resulting in power loss. larger (losses) with reduced efficiency. The aim of the research is to study the performance of unbalanced loads on open delta transformers and the research method is an experimental method in the laboratory, which includes testing on three-phase open delta transformers in unbalanced load conditions. The measurement results show that there are differences in performance (output results) in the influence of unbalanced loads between the average current and losses and the efficiency of the open delta transformer.

Induction-motor dynamic analysis during power-supply imbalances

It is widely recognized that the rotor-bar skin effect strongly influences induction-motor operation during unbalanced conditions. However, classic induction-machine dynamic models ignore this effect. A more general machine representation is derived that can predict the rotor-bar skin effect over the full range of dynamic induction-machine operation. The model is used to examine the starting of a motor fed by an open-delta transformer bank. The need to account for the rotor-bar skin effect is explained, and comparisons between motors starting with open-delta and balanced feeds are made.

Substation transformer connection effects on sensitive industrial loads

In electrical power distribution, it is both convenient and economical to use the open delta transformer connection to supply three-phase power to small consumers. Recently, however, problems such as rectifier failure in equipment power supplies have been attributed to this type of transformer connection. This paper presents the results of an investigation into the existence and severity of consumer problems arising from the open delta connection. It describes both theoretical and laboratory analyses of the presence of distortion in magnitude, phase angle and waveshape of the voltage and current waveforms. The analyses show that, although there are some conditions under which the open delta connection should not be used, in general the connection is suitable for supplying consumer loads.

Motor-Starting Lamp Flicker on Open-Delta Transformer Banks

When a motor is started through a transformer bank that serves both power and lighting loads, there is a dip in voltage on the lighting circuits. A digital computer study has been made of the voltage on the lighting phase during motor starting for the open-delta connection of transformer secondary windings. Equivalent circuits have been developed for the general case of the open-delta transformer connections having legs of different kilovolt-ampere ratings.

Combined Single-Phase and 3-Phase Loading of Open-Delta Transformer Banks

Combined Single-Phase and 3-Phase Loading of Open-Delta Transformer Banks

Unbalanced Open-Wye Open-Delta Transformer Banks [includes discussion

Unbalanced Open-Wye Open-Delta Transformer Banks [includes discussion

Sequence Networks for Faults on Open-Wye Open-Delta Transformer Banks [includes discussion

Sequence Networks for Faults on Open-Wye Open-Delta Transformer Banks [includes discussion