Why are resistance welding transformers smaller than regular air-cooled transformers?
Most resistance welder transformers are smaller than conventional transformers due to the duty cycle and the method of cooling. If a transformer is used less than continuous duty, the size will become appreciably smaller. An example would be using a 1 KVA transformer for 3 KVA intermittent load. The transformer will operate very satisfactorily as well as have a long life expectancy even though it may be operated at several times its normal continuous rating. The principal precaution which must be taken into consideration is temperature rise. The hotter a transformer operates, the shorter the life expectancy of the insulation. Sometimes resistance welding transformers have the appearance of being dry type, yet there are small copper tubes intermingled with the windings in which water is flowing. Water is a very excellent material to absorb heat rapidly, therefore, the heat is dissipated much faster through the water than if air spaces with fins were used. Development of welding transfor
