Transformer

Hello harihereus

Your DYn11 Transformer is coded as follows:

High Voltage Always capital letters
Delta - D
Star - S
Interconnected star - Z
Neutral brought out - N

Low voltage Always small letters
Delta - d
Star - s
Interconnected star - z
Neutral brought out - n

The 11 refers to the vector condition/Phase displacement of the transformer.

It is extremely important to ensure all transformers which may run in parallel connections, be of exactly the same vector number, otherwise heavy circulating currents may occur, with damages to transformers, lines and connected equipment - also preventing Protection relays from working correctly.

It is normal for both personal safety, and protection equipment, to connect Transformers Primary in Delta and Transformers Secondary in star, with the Neutral point brought out and earthed at the transformer.

Further information may be read here: http://www.eng-tips.com/faqs.cfm?fid=1090

If the geology for earthing is not good = desert sand or dry rock/shingle, then an Earth Mat should be made, to extend for some distance around the transformer plus connected equipment at transformer site.

In the same type of "earthing conditions" as above, it is good to earth the neutral at each switchboard, once again using an Earth Mat if a driven electrode gives a poor earth test.

Hope that assists you.

Kind Regards....

how is the actual connection of the tranformer with dyn11 winding configuration in the TNS?