An electric furnace consumes a power of 800 kW at a voltage of 220 V.

An electric furnace consumes a power of 800 kW at a voltage of 220 V. The winding of the furnace is made of nickel wire 72 m long. Find the wire cross-section.

To find the desired section of nickel wire in the furnace winding, consider the equality: ρn * l / S = R (winding resistance) = U ^ 2 / P, whence we express: S = ρn * l * P / U2.

Const: ρн – beats. electrical resistance (prin. ρн = 0.42 Ohm * mm2 / m).

Data: l – wire length (l = 72 m); P – power consumed by the oven (P = 800 W (800 kW for an electric oven); U – mains voltage (U = 220 V).

Calculation: S = ρн * l * P / U ^ 2 = 0.42 * 72 * 800/220 ^ 2 ≈ 0.5 mm2 (for P = 800 kW S ≈ 500 mm2).

Answer: Nickel wire should have a cross section of 0.5 mm2.