Transformer C.R.G.O. laminations are cut to the specified dimension, annealed and then assembled.
H.V and L.V coils are made in HV and LV coil winding machine as per design, varnished and then dried in chamber.
Assembled cores HV & LV coils are fitted and connections made with proper insulation. LV side connection is normally Star and which is done by blazing, and HV side is Delta which is done by soldering, and all connections are properly insulated with insulating tapes, bakelite tubes etc.
Assembly of cores and coil is then sent to bake chamber for raising I.R. value. When I.R. value has reached the desired level it is taken out and inserted in a transformer tank, leak tested and painted as per procedures.
Filtered and tested transformer oil is then poured in the core coil assembly in the tank through an oil filter machine. Now the transformer is ready for testing.
After successful withstanding of all routine tests as IS: 2026, it is ready for final inspection by the customer.