Chris Tromley wrote: > Do interpoles *only* reduce arcing? Without interpoles, brushes are only in the optimal position at one specific ratio between armature and field current. In effect, you need to run it as a series motor.
Interpoles (small field poles between the main poles) are a first-order correction for the shift in optimal brush position as a function of current. Now you can have a 4:1 or so change in field current. Compensating windings (which distribute the interpole winding completely around the field) are a second-order correction, that virtually eliminates any shift in optimal brush position with current. Now you can have a 10:1 change in field current. There are still third-order effects, from extremely high rpm and magnetic saturation effects. -- Lee A. Hart Ring the bells that still can ring 814 8th Ave. N. Forget your perfect offering Sartell, MN 56377 USA There is a crack in everything leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
