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G44SPT

- 4

- 0

- Homework Statement
- ii) what is the no load magnetising power loss?

- Relevant Equations
- R0 = V1/(Icosϕ) & X0 = V1/(Isinϕ)

The study material says under 'Estimation of magnetising losses' :On no-load, the rotor current is very small and the slip almost zero. Therefore, R′2s is very high and virtually no current flows through the branch of the circuit containing R′2s. Consequently, the no-load current is virtually equal to the current through the resistor R0 and the reactance X0, and the power taken from the supply on no-load is virtually equal to the core losses in the motor.

Therefore , R0=V1/Icosϕ and X0=V1/Isinϕ

In answering ii) using the notes:

V1 = 230

I = 4.8

ϕ = P.F (power Factor)

p = 470

P.F = P/(1.732 x V x I)

P.F = 470/(.732 x 230 x 4.8)

P.F = 0.246

using formulae from notes:

R0=V1/Icosϕ and X0=V1/Isinϕ

R0=230/(4.8cos0.246) and X0=230/(4.8sin0.246)

R0=47.92w and X0= 11160.29w

The magnetisation losses seem too large since the actual stator power is only 470w? i think i must be missing something to be getting such a large magnetisation power loss.