# 3 phase induction motor core loss calculations

#### Ande

Joined Feb 3, 2017
44
I have worked out what I think is the solution to a 3 phase induction motor problem but the stator core loss value obtained seems too high to be right. Please help. Question 3 is the one I need help with, the other questions have been given for background purposes. My attempts are attached.

A 3 phase 6 pole induction motor has a star connected stator with impedance (0.5+j2.5) while the rotor standstill impedance is (0.1 + j 0.6). The shunt impedance is 12+j61. If the supply voltage is 630V and the effective turns ratio is 2:1, calculate the ff at 965 rpm

1. Rotor impedance referred to the stator
2. Stator current and pf
3. Stator copper and iron loss

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#### drc_567

Joined Dec 29, 2008
1,156
You might review the calculation of Z0. That value carries through and might affect the final answer, as I understand your notation.

#### Ande

Joined Feb 3, 2017
44
You might review the calculation of Z0. That value carries through and might affect the final answer, as I understand your notation.
As far as I know, Z0 represents the no load loss (hence the parallel branch) which is why I've calculated it the way I did. Kindly provide some insight as to what I need to review. Thanks

#### drc_567

Joined Dec 29, 2008
1,156
The calculation of R0||jX0 is incorrect, in particular the angle is only 2.3 degrees, not 11.1 degrees.

#### Ande

Joined Feb 3, 2017
44
The calculation of R0||jX0 is incorrect, in particular the angle is only 2.3 degrees, not 11.1 degrees.
Since this is a parallel network, the impedance can be calculated as: Ro(jXo)÷(Ro + jXo). That's what I've done and I keep getting the same answer quoted above. Is my technique incorrect?

#### drc_567

Joined Dec 29, 2008
1,156
You are correct ... neglected to convert rectangular coordinate to polar. My apologies.

#### Ande

Joined Feb 3, 2017
44
You are correct ... neglected to convert rectangular coordinate to polar. My apologies.
Does the rest of the work look correct? I'm still skeptical about the answer

#### drc_567

Joined Dec 29, 2008
1,156
The numerical calculations shown appear to be numerically correct. The only question is in 3.3, where the radial magnitudes of V and I are used to calculate the corresponding power losses, rather than using the real part of those vectors.