A cylindrical transformer coil made of insulated copper wire has an inner diameter of 16 cm and an outer diameter of 24 cm. Sixty percent of the total construction of the coil is copper and the rest...

A cylindrical transformer coil made of insulated copper wire has an inner diameter of 16 cm and an outer diameter of 24 cm. Sixty percent of the total construction of the coil is copper and the rest insulation. The density of the current in the conductor is 190 A/cm². The specific resistance of copper is 210
10^–6
W cm²/m. The heat transfer coefficient on both surfaces of the coil, which are cooled by air at 20°C, is 23.26 W/m²
K. The thermal conductivity of the coil is 0.35 W/m K. Find the maximum temperature in the coil. Assume the coil as a plane wall with the thickness 2l = 4 cm.