The R is not ignored and there are no base conversions.
Here are the formulas to get the MVA values needed for a motor start check:
System: MVA = MVA_base / Z_system_pu
Line: MVA = kV^2 / Z_?
Xfmr: MVA = MVA_rated / Z_pu
Motor: MVA = kVA / X"d
waross,
I use the MVA for a quick check of volt drop & fault, not for a detailed analysis. I use an impedance calc for the details. I have noticed some difference in the results but nothing earth shattering.
I'll add the power factor to my MVA quick calcs and see if the results get appreciably...
If you use the MVA method, the voltage drop = load MVA / (load MVA + source MVA).
In this method, series and parallel MVAs are combined using the same formulas as capacitors. In the case of motor starting, sources use the SC MVA and the motor uses the starting MVA.
schell44,
I might buy into one of the primary loops being called the "Asbury loop" due to location. Also, you might want to clamp the ground wire to the concentric neutral.
The problem is that is makes no sense to name and isolate one primary as such. If you would bond one, you would bond...
zachz,
I think someone at your place of employment is yanking your chain. The diagram you show is for a two-bushing transformer. With the two-bushing transformer, the H2 bushing could be connected the one of the primary phases or the primary neutral depending on the system voltage and...
