How to Check Transformer Vector Group Manually

by : Rifky Cahyadi

Procedure of Testing the Vector Group of a Transformer manually can be done as below steps.

Let’s have a Ynd₁₁ transformer as an example.

1.      Observe the vector group of Ynd11 (figure 1), find the nearest vector of LV winding which is parallel with the HV winding, Let’s define it to be 1U and 2W.

                                               Figure 1

2.      Connect neutral point of star connected winding to earth/ground.

3.      Join 1U of HV winding and 2W of LV winding together (see figure 2).

Figure 2

4.      Apply three phase supply to HV terminals, 380Vac or 415Vac choose based on the most convenience.

5.      Measure voltages between terminals 2U – 1N, 2V – 1N, 2W – 1N, that means voltages between each LV terminal and HV neutral.
 

6.      Also measure voltages between terminals 2V – 1V, 2W – 1W and 2V – 1W.

7.      Based on the vector combination in figure 2, we can see the length for each connection. Thus for Ynd₁₁ transformer, we will find :
2U – 1N > 2V – 1N > 2W – 1N
2V – 1W > 2V – 1V or 2W – 1W

8.      Compare the result of the measurement, if all the measurement result fulfill the condition in step 7, then the vector group of the Transformer is confirmed OK.

The vector group test of transformer for other group can also be done in similar way. Figure 3 can be used as a reference guide to do the testing.

                                                       Figure 3