An open circuit test is conducted on a 1100/110 V, 50 Hz single-phase transformer with instruments connected on the low voltage side of the transformer.
An open circuit test is conducted on a 1100/110 V, 50 Hz single-phase transformer with instruments connected on the low voltage side of the transformer. The voltmeter reads 110 V. The ammeter reads 2 A. The wattmeter reading is 65 W. The approximate core-loss resistance and magnetizing reactance, referred to as the low voltage side, are respectively.
Right Answer is:
186.15 Ω, 57. 575 Ω
SOLUTION
Given
Vo = 110 V
Io = 2 A
Po = 65 W
Power can be expressed as
Po = VoIo Cosφ
Cosφ = Po/VoIo
Cosφ = 65/110 × 2
Cosφ = 0.295
∴ sinφ = 0.955
The core loss component of the current can be expressed as
Iw = IoCosφ
Iw = 2 × 0.295
Iw = 0.6W
Magnetizing component of current can be expressed as
Im = Iosinφ
Im = 2 × 0.955
Im = 1.9 A
Cores loss Resistance
Ro = V/Iw = 110/0.6
Ro = 186.44 Ω
Magnetizing reactance
Xm = Vo/Im = 110/1.9
Xm =57.89 Ω