Gary Neal wrote:
...........
>7.      Moved the caps to the terminals right on the motor - better
>success.  Failed probably 1% of the time.
>

Good to hear things are coming along. You might try small R's
[10-100 ohms] in series with the caps, since you will get a
current surge into the cap during relay contact closure otherwise.
You get L di/dt [from motor] at contact opening and C dv/dt
[from cap] at closure.

Also, as others mentioned, if the caps are too big the sol'n
is self-defeating due to series inductance/etc. Effective
snubbers for switching "amp" loads at 220VAC usually use no
more than 0.1 uF or so - but they usually have series R's too.

If using separate motor gnds and also snubber at the motor
doesn't do the trick, then you may need to go in and strenghten
spike rejection circuitry throughout the entire conotroller. I
have been involved in this sort of thing, and sometimes it
takes appropriate components placed in "many" places before
the system is reliable.

BTW, are your current 1% failures occurring at relay "closure"
or "opening" ?????

- dan michaels
www.oricomtech.com
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