A 440:110 ratio single-phase transformer draws 5Amps on no load at 0.9 power factor, calculate the value of; I) magnetizing current. (Ii) core component of current

Solution

V1 = 440v, V2= 110V,

no load current = 5A, p.f = 0.9
Cos theta = 0.9,

theta = cos^-1 [0.9], theta = 25.84°

I) magnetizing current = no load current × sin theta
= 5×sin 25.84
= 5 × 0.44
magnetizing current, Im = 2.2A

II) core current = load current × cos theta
= 5×0.9
Ic = 4.5A
Iron loss = V1 × no load current × cos theta
= 440 × 5 × 0.9
= 1980W