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Originally Posted by gc02
The 884 I checked is about six months old and it was defiantly 120 Hz. It's quite possible the frequency was changed at some point. I think the 883s were 2 kHz, but I've never actually checked one of those.
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Greg et al,
The reference in Kevin's post:
http://www.enigmaindustries.com/links.htm lists the 884 as 120Hz and the 883 as 2kHz, hence my confusion. (being around for a long time does get in the way.) Greg, are you in a position to check rise time where you are right now?
Jim,
(I am confused and keep calling you Rick) You tell us that the motor is unloaded but it is connected to the FP gearbox. That is a load. The numbers in your table suggest the large amount of friction present at low speeds in that FP gearbox. At low speeds, a motor still must overcome internal losses due to friction, brush pressure and magnetic influences. On the FP motor in particular, there are only three commutator segments which means three windings. Depending on the duty cycle, energy may only be supplied to the motor for a small portion of the brush/commutator cycle at low speeds. If analyzed, you may find that current is only flowing to one winding at a time instead of two. (two gives better torque/output/higer current) In contrast, the drill motor has several windings/commutators and the spec sheets illustrate the difference in these two motors. Ironically, the graph you displayed in your earlier post is a typical charge current graph of an inductor. This may indicate the effect of the duty cycle vs. inductance or not.