vinod said:
What is the defferance bettween the transformwer type like DY1, DYN etc. Please give basic explenation
I see from your location, and question that you are working in IEC terminology.
The basics: Refer to IEC std 60076 part 1.
In short: First letter capital = HV side of transformer, followed by a "N", means with neutral. The lower case letter is the low voltage side, if it contains an "n" then a neutral is involved. The number refers to the phase relationship of the low voltage side to the high voltage side. It is oriented around a 12 hour clock, with each number 30 degrees apart.
example: Dy1 = hv voltge is Delta, low voltage is wye, the lv voltage side lags the HV side by 30 degrees.
example: Dyn5 = HV side delta, lv side wye with a grounded neutral, lv side lags hv side by 150 deg.
read through std 60076, it is very helpful, good luck!