Which type of winding use in power transformer?

The transformation ration for a transformer is (Vs/Vp) = (Ns/Np).

Which means, Voltage ∞ No. of turns.

So, we can say if we have to increase voltage, then we have to increase the no. of turns, and as the no. of turns increase the space between the core and the winding reduce.

So, from above we can say that the HV windings are closer to the core than the LV windings.

There are two configurations for windings in Transformers.

The first is called 'concentric' or 'tubular', in which the low-voltage windings are placed innermost (i.e. closest to the core) with the high-voltage windings outermost.

The second is called 'sandwich', in which the windings are arranged in ring bundles, with alternate rings of high- and low-voltage windings placed one above the other.

The first configuration is used with 'core' type cores, with half the LV/HV windings placed around one limb of the core, and the other half of the windings placed around the second limb. The second configuration is used with 'shell' type cores, with the ring bundles placed around the centre limb.