Electrical Transformer Vector Group Testing, Voltage Method

Vector Group Test of Transformer

The vector group of Electrical power transformer is an essential property for successful parallel operation of transformers. Hence every electrical power transformer must undergo through vector group test of transformer at factory site for ensuring the customer specified vector group of transformer.

Vector group testing is done to ensure the parallel operation of three phase transformer connected in the power system. There are various ways of connecting three phase transformers with phase shift of 00 ,±300 and 1800 .This phase shift is due to different ways for connecting the primary and secondary windings of the transformer. To connect the various transformer, the secondary waveform should be same for all the transformer otherwise a large circulating current will flow in system that may cause short circuit.

The phase sequence or the order in which the phases reach their maximum positive voltages, must be identical for two paralleled transformers. Otherwise, during the cycle, each pair of phases will be short circuited.
The several secondary connections are available in respect of various primary three phase connection in a the three phase transformer. So for same primary applied three phase voltage there may be different three phase secondary voltages with various magnitudes and phases for different internal connection of the transformer.

In this lecture I have explained in detail, how to draw & connect Vectors and perform vector group testing & learn the wiring circuit.

I have explained the concept in a way that you will be able to draw, connect & test vector group without memorizing it.

I am always available to reply your question.

Thanks

Muhammad Kashif