Efficiency= output power/input power
efficiency = (v*i*cosφ)/((v*i*cosφ)+(x² Pc)+(Pi)) x=fractional part of full load
Over excitation : leading current
Under excitation : lagging current
Normal excitation : current with unity PF (in phase current)
Initial inrush of magnetizing currents have high component of even and odd harmonics.
2nd - 63%