to calculate transformer windings

Hi there, thanks.

I like to know if there is 35 turns in the primary winding of a transformer and 280 turns in the secondary, how many volts is needed in the primary to result 1100 volts kindly reply.

Thanks
Ron

Assuming a perfect transformer to voltage on the primary relates to that on the secondary according to the turns ratio. Your transformer will step up by a factor of 280/35.

say n1 turns = primary side
n2 = secondary side turn
then by formula
n1/n2 = vp/vs
where vp = primary voltage
vs = secondary voltage
here..it is given that
n1=35
n2=280
vp=?
vs=1100 volt
therefore
35/280 = vp/1100
so vp = (35*1100/280)
= 137.5 volt
nearly equal to 138 volt.