We had several additional incidents after that, and then I cleaned all the contacts on the pressure switch and cleaned and tightened the circuit breaker connections at the main feed panel. And then it was pretty much fine after that (we did have one overload trip incident in February, but none since.)
Tonight, I was flushing the water tanks, which called for shutting off the pump and draining the system. I started and stopped the pump a few times to agitate the sediment at the bottom of the pressure tank, so it would drain out. After a few cycles, the pump refused to start up again. It took 20-30 attempts before I was able to re-start it. And then after it'd been running for a minute, I'd shut off the breaker and wait for the pressure to drop and turn it back on, but the pump would not start.
So here's where my wire color question comes in. I can't find anything on Google about this:
What are the functions of the Black, Red and Yellow wires? Can anyone point me to a schematic of the pump motor (1-phase, 220V)?
Here's what I am observing when the pump fails to start:
Black to Red: 220V Black to Yellow: 220V Red to Yellow: almost zip, less than 10V
When I finally got the pump to start, I took another set of readings.
Black to Red: 330V Black to Yellow: 220V Red to Yellow: 220V
I note that the red and yellow connect to a relay. I am wondering if that relay might be intermittent (although, I can smack it with the back of a screwdriver handle and it doesn't help, so I think it's not a mechanical problem). The capacitors look like the day they were manufactured. No leaking electrolytes, no rust.
If the motor were physically stuck (locked rotor), what would I expect to see in terms of voltages on the three wires? The house lights hardly dim when I turn the pump on, but the overload will always trip in about 3 seconds.
Given these facts, where would the problem be most likely to be located?
Help is appreciated. Thanks!
-- Take care,
Mark & Mary Ann Weiss
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