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[email protected] etpm@whidbey.com is offline
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Default How to size motor start cap?

On Wed, 18 Jul 2018 18:10:37 -0500, "Dave M"
wrote:

What's the model#/part# on the nameplate of the motor? Also, many
nameplates specify the required capacitors for the motor. Have you looked
there yet?

Dave M

wrote in message
.. .
Relative to my previous post today I need new starting caps for a 3
HP single pahse 230 volt motor. Dayton (Grainger) no longer has any
info about this motor.
The caps that blew were connected in parallel. One was 560-552 MFD
and the other was 540-648 MFD. The caps were not original and they
were from China. From looking on the web it seems like this much
capacitance is a little high.
The motor is an old motor. Maybe 40 years old. Maybe older.
The cap housing is large enough for two caps and the wires
connecting the caps in parallel looks exactly like the wires going
into the motor from the caps. Same kind and color of insulation and
same look from aging. So the big cap housing appears to have been
meant to hold two round caps and not one big rectangular cap.
Maybe it was hard to get as much capacitance in the same space
years ago and that's why the two caps.
If the capacitance is too high can that stress the caps enough to
blow their guts out?
Thanks,
Eric


I looked up the motor number and Grainger, which sells Dayton Motors,
no longer has data on the motor. Neither did an internet search yield
anything. And the motor nameplate doesn't specify the caps. I though
that maybe a newer Daytom motor would have the info but Grainger does
not list the caps required for the motors on their website or on the
motor nameplate. I can't understand why.
Eric