084f2db8c6 For smaller sized transformers the tanks are usually smooth surfaced, but for large size transformers a greater heat radiation area is needed, and that too without disturbing the cubical capacity of the tank. The oil helps in transferring the heat from the core and the windings to the case from where it is radiated out to the surroundings. If the turns ratio is equal to unity, n=1 then both the primary and secondary have the same number of windings, therefore the voltages and currents are the same for both windings. For the primary winding emf, N will be the number of primary turns, (NP) and for the secondary winding emf, N will be the number of secondary turns, (NS). Shell-Type Transformer In shell-type transformers the core surrounds a considerable portion of the windings. This is the simplest form of electrical power transformer and this is the most basic of working principle of transformer. Then we can see that the same voltage is induced in each coil turn of both windings because the same magnetic flux links the turns of both the windings together. As the ratio moves from a larger number on the left to a smaller number on the right, the primary voltage is therefore stepped down in value as shown. Monostable Multivibrator.