Very thin wire in an ac motor?

[Arnak]

Hi,

I recently had to repair a small (Hobby) single phase 240V AC motor.

The fault was that one of the wires from the field coils (stator) to one of the brushes had broken.

The repair worked fine but I wondered why such very very thin wire is used from the coils?

When I say thin I mean not a lot thicker than a human hair, I assume that there is a reason for that?

Can anyone explain that for me, please?

Thank,

Martin

 

[crutschow]

I assume that there is a reason for that?

Yes.
For a small motor to operate from 240Vac, the field coil inductance must be very high to minimize the field current and keep the core from magnetically saturating, which requires a lot of turns.
To get a lot of wire turns around a small coil requires the use of very thin wire.

 

[Arnak]

Yes.
For a small motor to operate from 240Vac, the field coil inductance must be very high to minimize the field current and keep the core from magnetically saturating, which requires a lot of turns.
To get a lot of wire turns around a small coil requires the use of very thin wire.

Great, thanks for the answer!

Martin

 

[Minder]

Also must be a Universal motor (AC/DC) if the fields are in series with the armature as it sounds.
The rpm on these are controlled principally by the load