Transformer Design

Calculate voltage per turn first and then core x-sectional area. To get optimized results You have to repeat this excersice few times. Approximate Volatge per turn can be calculated by multiplying "K" with KVA rating. K value can be selected from 0.3 to 0.7 depend on KVA rating.

thanx for repying me sir,according to your answer i havedone the calculation for voltage per turn as 25kva*0.3=7.5 now 7.5 is the voltage per turn , so now what i have to do by which i can get the turns of LV side and why we have to calculate the cross sectional area ,what is the role of cross sectional area here.

Please see the links below. You can find the flux density from the calculated data (cross-sectional area of core, voltage, number of turns) and compare it with the 1.5 T desired.

The current densities can be obtained by selecting a bigger conductor (if there is physical space). After you have the number of turns and type of conductor, the losses can be determined.

http://hyperphysics.phy-astr.gsu.edu/Hbase/magnetic/transf.html

http://ecee.colorado.edu/~pwrelect/book/slides/Ch15slides.pdf

Thanx for giving me the links Mr Tomad , here cross sectional area can be easily find by AREA=Vs/Ts/(4.44*Hz*Bm) But here for finding area i need number of turns at LV side. Compleate design of 25 KVA i have done by taking the help of lV turns , this time iam on way for learning design. I need to compute the turns as much as approx. and in our tender specification flux density 1.5 T, Current density at lv is 2.8,current density of hv is 1.8 of 25 KVA (11/.433KV) has given , so by the help of both current density we can compute or manage the wire size or size of conductor and also my way of design is like that i have to compute turns first by the help of above parameters,so plz help me for this.