Re: [CAD_CAM_EDM_DRO] Stepper Motor (was: Harrison Lathe and Gecko's)

In a message dated 2/7/2003 8:44:39 PM Central Standard Time,
wotisname@... writes:

> I want to check my Z axis stepper motor. Is it wise to do the insulation
> test with a mega?
>
> The resistance readings are 0.4 ohms across either pair of wires, there are
> four coming out of the motor. Which is twice what the manufacturer quotes
> for a single coil, so they must be wired in series inside?
>

Terry: A "megger" is a kind of ohmmeter that measures VERY high resistances
in the huyndreds (or more) MEGOHMS range. For steppers, the resistances are
generally less than ONE ohm to only a few ohms for some "higher voltage"
types.

You should have "infinite" resistance between each winding! If you read 0.2
ohm between 1 and 2, and also between 3 and 4, there should be infinite R
between 1 and 3 or 1 and 4, or 2 and 3 or 2 and 4. If you read 0.4 between,
say, 1 and 4, there would be ZERO ohms between 2 and 3, indicating a "short"
internally, between 2 and 3. Try again, noting the R between EACH pair of
wires, and try to SKETCH a diagram to help you visualize this!

Lotsa luck! Jan Rowland


[Non-text portions of this message have been removed]