Changing Transformer Usage

Two possibilities spring to mind:

1. Install a zig-zag transformer to provide the neutral
2. Buy a replacement transformer with a star point that can be used as neutral.

How are you going to do voltage regulation(OLTC)?. Will your area code allow to use an earth connected to transformer body as neutral?.

Hi Anon

You can install a delta/star neutral earth reactor (compensator) on the LV side to provide a star point for for the neutral which also makes it possible to limit the earth fault for protection purposes.

If the transformer is to be operated in parallel with other transformers (not good on the secondary side) off the same MV bus then the characteristics (vector group, impedances) should match. This will prevent circulating currents which your protection won't like.

Also it may be a good idea to carry out a sweep frequency response analysis on a transformer of that age to ensure that you're not installing a unit which will not last too much longer. Doble Engineering can help you with this.

Good luck

Use a zig-zag tranformer to ground delta winding.

Install a zig-zag transformer to provide the neutral Imade it before to nutral to erect earth fault protection .

Trade in your old transformer and replace it with one that is correct for your application.

It may work out to be around the same price as any augmentation, be more reliable, efficient, simpler, take up less space, be faster to implement.... and not look like it was lashed together by a bunch of stingy students.