[a Bill]

I guess this is the right forum, move it if need be.

I was just curious what the advantages of the various armatures with different numbers of poles was. Most of these haven't been made in ages but you still see them pop up every now and then.

Now I'm guessing that they settled on the three pole design simply because it was the best compromise of power, ease of use and ease of manufacturing. I actually found a Mabuchi armature with two poles at my house. It uses the same size can as the Scalextric cars, weird. I also saw a seven pole armature recently. More poles equal smoother running? Any ideas? Was this covered in a FAQ I missed?

 

[ProfFate]

Hi

In general, more is smoother, not quite as quick, much more expensive.

Odd number makes the motor easily self starting, even causes problems with stalled fields.

Fate

 

[a Bill]

Thank you. That's what I was looking for.

 

[howmet tx]

There was quite a lengthy discussion about the number of poles on various motor arms back in February, if you want to have a look- it was in the 'History, Culture and Literature section, the thread called 'MRRC- what's the story?'

 

[Tropi]

Poles . . .
QUOTE Odd number makes the motor easily self starting, even causes problems with stalled fields.
A bit of lateral thinking . . .
Odd numbers of magnets would reverse this.
Three magnets would permit self-starting 2 and 4 pole motors.
Wonder if it has ever been done?
It would make the motor fatter and heavier of course, but are there other reasons not to? I realise there is no way this hasn't been thought of, even before I was born but I'd love to hear the theory and practice, if any.

 

[Fergy]

QUOTE there is no way this hasn't been thought of, even before I was born

Were there motors back then?

How would you orient three magnets so that two adjacent magnets didn't have the same polarization?

 

[Tropi]

Ahem . . .

I have a feeling that no matter how much thought I give that one, it will remain the killer reason for not doing any more of that line of lateral thinking!

Wanders off mumbling incoherently . . .

 

[Tropi]

Wanders back, still mumbling, but slightly more coherently!

Here's a link for a Mono-mag Motor - cute!

And why don't we stop messing around with permanent magnets and use 3-phase AC anyway?

 

[ProfFate]

Hi

AC phase really limits your RPM.

Fate

 

[Fergy]

Yes, it does, Fate! But can you imagine the torque from a big, honking, 3 HP AC motor?

 

[a Bill]

Household current in the US is single phase so three phase is right out of the picture unless you put in a request with your power company. The old HO Aurora Vibrator cars used AC power but it wasn't really powered by a motor, per se. It was also pretty slow unless you fiddled with it. I'd rather stick with DC for now, thank you.

The MRRC link was good. I should have used the search function with motor and poles as keywords rather than read all the titles of all the threads, as I did. Has anyone put together a FAQ for Slotforum.com yet? It would help keep repetitive queries such as mine to a minimum.