Question

Determine the hysteresis loss in an iron core weighing 50 kg having a density of 7.8 × 10³ kg/m³ when the area of the hysteresis loop is 150 cm² , frequency is 50 Hz and scales on X and Y axes are : 1 cm = 30 AT/cm and 1 cm = 0.2 Wb/m² respectively.

Answer 1

Hysteresis loss = xy (area of B/H loop) J/m³ /cycle 

1cm = 30 AT/cm = 3000 AT/m ; 1 cm = 0.2 Wb/m² 

x = 3000, y = 0.2, A = 150 cm² 

∴ loss = 3000 × 0.2 × 150 = 90,000 J/m³ /cycle 

Volume of 50 kg of iron = m/ρ = 50/7.8 × 10⁻³ = 6.4 × 10⁻³m³ 

∴ loss = 90,000 × 6.4 × 10⁻³ × 50 = 28,800 J/s 

or watts = 28.8 kW