On Friday, 25 August 2017 02:25:46 UTC+1, Rheilly Phoull wrote:
On 25/08/2017 6:31 AM, wrote:
I run my machine shop off af a rotary phase converter. It has
starting caps that are switched out of circuit after the motor is
started.
Lately the device sometimes has a hard time starting. I switch it
on and the motor may not come up to speed practically instantly, the
way it is supposed to. If this happens I turn off the breaker, wait a
minute, and then try again. It always starts fine on the second
attempt. Except this morning it took three tries for the thing to
start. The motor did actually spin up some this morning on the first
try but it was really slow starting so I shut the breaker off.
I suspect starting caps but wonder why the second attempt always
worked until today. And then today it started fine on the third
attempt.
The phase converter has been started almost daily for at least
fifteen years using the same breaker in the main breaker panel.
I thought that maybe the breaker might be making a bad contact on
one leg of the single phase 250 volt input. Or maybe a contactor
inside the converter is not making good contact. Or maybe, and I think
most likely, the starting cap(s) is(are) the problem. I just wonder
why, if the thing doesn't start spinning right away on the first try
it does on the second or third.
This weekend I'll have time to look inside the phase converter and
I would like to know if there is a way to diagnose the starting caps.
The contactor contacts I know how to check. And I could buy a new
breaker. But I would like to not just buy stuff until the thing works
properly.
Advice?
Thanks,
Eric


After 15 years I reckon I would just get another cap and see if that
fixed it. What sort of device takes out the cap, centifugal ?

Or as a quick test clip some additional C across it.


NT