Re: [femm] help

["mercedes sampere" <m_veinti2@xxxxxxxxxxx>]

David,
I'm searching on dispersion reactance for induction motors, so actually I'm 
interested about self inductance but I calculate mutual inductance in order 
to have an idea if the model is OK.
I took the model for this motor from a design handbook and that's why I 
think I'm doing something wrong, because it doesn't make sence that self 
inductance would be greater than mutual inductance for a motor, unless it is 
not properly designed.
You're right about coils, what do I have to do to drive them in series?
About current, in the original model stator current was 88.8 A but I've 
increased it to see if I could get less leakage.
These are motor features:
Usefull power: 81kW
Tension: 380/660V
Synchronous speed: 1500rpm
Frecuency: 50Hz
Number of phases: 3
2 pairs of poles
Power factor: 0.89
Sliding coefficient: 0.0133
Current per phase(stator): 88.8 A
Number of slots(stator): 48
Current per phase(rotor): 377 A
Number of slots(rotor): 36

Should I get better results if I model the hole geometry (I mean not only 
two slots)?

Thank you very much
Excuse my english

Mercedes

> From: David Meeker <dmeeker@xxxxxxxxxxxxxxxxx>
> Reply-To: femm@xxxxxxxxxxxxxxx
> To: femm@xxxxxxxxxxxxxxx
> Subject: Re: [femm] help
> Date: Fri, 21 Sep 2001 09:49:44 -0400
>
>
>
> mercedes sampere wrote:
>
> > Hello
> > I'm trying to simulate the model I send you. It's a part of an induction
> > motor (only two slots, one from the stator and the other from the 
> rotor).
> > The problem is that self inductance for any slot is bigger than mutual
> > inductance between them, and this couldn't (or shouldn't) be.
> > I've tried with other materials but I can't find the problem.
>
> Like Keith was saying, it is generally perfectly reasonable for the self 
> inductances to be larger than
> the mutual inductance because of slot leakage, which bumps up the self 
> inductance, but doesn't increase
> the mutual.
>
> Anyhow, there are a couple of other things you should also think about with 
> your geometry. Each of the
> coil regions has all wires being members of either the "estator superior" 
> or "estator inferior"
> circuits. Defining things this way makes things behave like a single big 
> multi-stranded conductor (i.e.
> driven in parallel), rather than a bunch of turns that are driven in 
> series. Is this what you intended?
> Also, I'm guessing that this is part of a motor that you're modeling. 
> However, the domain that you are
> modeling and the currents that you've defined don't make much sense to me. 
> Could you take sort of a
> step back and say something about the machine that you are trying to model 
> and what result you are
> trying to obtain? Then, it would be easier for me to say something useful.
>
> Dave.
>
> << dmeeker.vcf >>


_________________________________________________________________
Descargue GRATUITAMENTE MSN Explorer en http://explorer.msn.es/intl.asp