Does anybody know some link on free software for calculation of induction motor parameters from rated- nominal parameters (voltage, power, power factor, moment of inertia-GD2)?
Hello,
You could try ETAP. But I am not sure about GD^2 parameter.
Also, most parameters would be vendos-specific. So at best, the software could tell you approximations.
Regards,
Digsilent is the best software for calculation of induction motor parameters in order to get characteristics for relay protection coordination. But it isn't a free software.
Regards, Alen
Electric Drives and SimPowerSystems in Matlab
Pls visit this site
in.mathworks.com/help/physmod/sps/electric-drives.html
Alen, we have DIgSILENT resarach, commercail and student versions. I will check that option?
From the nameplate one can calculate the nominal losses. A good estimate for closed motors up to 20 kW. It is for a warm motor. Nominal losses are the apparent power*power factor - losses.
66% loss in the stator, 33% loss in rotor, 1% mechanic (bearing and fan).
The stator: 44% in copper, 22% iron and other no load loss. The rotor loss determines R2 in warm state (DC value) It can also be estimated from the nominal speed. The magnetising current is about 40% of the nominal current. So one can calculate R1.From the starting torque and current one can determine R1+R2 at 50Hz (skin-effect). The leakage can be determined from the peak torque. The magnetising inductance is voltage dependent. It becomes different if you choose for L,T,inverse L scheme. It becomes more complicated if one needs to choose the find of non-linear model. Magnetising non- linear? leakage non-linear or both non-linear, One can create his own model in a mathematics programme: Mathcad, Maple, Matlab, even in Excell. It gets close to network analysis.
Larger motors have a bit less magnetising current and less than 33% rotor loss.
Inner cooled (open motors) can afford more rotor loss and will have a higher R2.
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