Abstract: A transformer for adjusting the voltage supplied to a load, the transformer comprising a primary winding connectable to a primary AC electrical supply and a secondary winding connectable in series between a live supply and a load. The primary winding comprises a switching means operable to change the number of turns of the primary winding connectable to the primary AC electrical supply where the number of turns of the primary winding connectable to the primary AC electrical supply is greater than a number of turns in the secondary winding. The switching means comprises one or more solid state switches.