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	Subject - transformers kishore_7_sep@yahoo.co.in why in a transformer the core is varnished JimmyDee The core is built of thin layered stampings of a special silicon steel and insulated from each other by being varnished to reduce heat that is produced by small eddy currents. These eddy currents are produced within the steel core by the alternating magnetic flux lines cutting a small portion of the steel and creating a very small short circuit within the steel itself. There are thousands and probably millions of these small currents produced in a transformer core. If we had a soft solid cast iron core that was not laminated, it probably would get hot enough to melt the core. Laminating and insulating with varnish reduces this heat loss to 2% or 3%. We utilize eddy currents in a steel core as the principal of how an induction furnace works. In the induction furnace the eddy currents are in the thousands of amps and voltages are close to zero. This is used to melt iron and steel. Hope this lengthy discussion helps. Jim