GA Tech vs EE Guide Induction Motor Equivalent Circuit

[thebard]

Hi All,

I see some differences between the GA Tech equivalent circuit for an induction motor vs the EE Guide to Passing the PE. The GA Tech has the stator impedance between the input and core impedance, whereas the EE Guide has the stator impdance on the other side. I'm looking at pages 7-RM-34 in GA Tech and 86 in EE Guide respectively.

Thanks.

 

[Stephen2awesome]

I don't' think I have an EE guide but trust the GT model. It is the same model Electrical PE Review uses. I have the GT book and also doing the Electrical PE review by Zach.

 

[rg1]

Hi All,

I see some differences between the GA Tech equivalent circuit for an induction motor vs the EE Guide to Passing the PE. The GA Tech has the stator impedance between the input and core impedance, whereas the EE Guide has the stator impdance on the other side. I'm looking at pages 7-RM-34 in GA Tech and 86 in EE Guide respectively.

Thanks.

I do not have both but I understand the issue. Both the equivalent circuits are correct. The second one in which the stator impedance has been taken towards rotor side is more approximation. For larger Machines (Wildi says above 2hp) the approximate model is also okay. For short circuit condition (Locked rotor) when the parallel branch carries lesser current also the approximation is okay. It depends how the approximation changes your result and how accurate you want to be in your results. In a transformer  eq. ckt. also it is similar. Hope it answers the doubt.