Which term describes heat loss due to the resistance of the transformer windings?

• A. I2R Loss
• B. Core Loss
• C. Dielectric Loss
• D. Stray Loss

Answer: (A)

Heat produced in the winding due to its resistance is called I^2R loss. When current flows through the winding, the resistance converts part of that electrical power into heat, and the amount of heat is given by P = I^2R. This loss is also known as copper loss because it comes from the winding material (usually copper) carrying current, and it increases as current or winding resistance grows (resistance rises with temperature).

This is different from core loss, which comes from the magnetic core itself (hysteresis and eddy currents in the core), dielectric loss, which occurs in the insulation, and stray loss, which involves eddy currents and other losses in non-winding parts due to stray magnetic fields.