How about some responses? Is my pump overheating leading to increased current?
I have a 1 1/2 HP sub (3 wire, single phase) sitting at about 125 feet down powered by a 7500 watt generator (Troy-Built). Two weeks ago while pumping, my generator SUDDENLY groaned heavily, coming VERY close to a stall, then recovered to normal rpm. Inspection disclosed that the overcurrent sensor on the well controller box had tripped, removing the load and allowing the generator to recover.
First thot was something jammed in the pump impellers. Waiting a couple hours before I had a chance to try again, I found that the pump ran normally and completed filling the tank. Crossed my fingers that the problem was gone. However, within a week, and several times since then, the generator has strained -but not stalled- before the overload sensor tripped.
I went out and bought a clamp-on current meter to help me debug the problem.
Today I was lucky enough to catch the problem in the act. When starting the pump was running normally and voltages were at a solid 240 and running current was: Yellow about 11.8 amps, Black a bit lower, Red = 1.3 amps. After about 3 minutes, I noticed the Yellow current start to increase. First, from 11.8 to 12.1 to 12.8, etc, and finally up to almost 16 amps when the breaker tripped. The generator was laboring at that point. During the time the current was increasing, the Red current remained at 1.3 amps. (I didn't get to check the Black current but assume it would have to be increasing with the Yellow.)
Earlier I had checked the Start and Run capacitors (open circuit) and they behaved normally, with "resistance" increasing over time as they charged from the meter current. I assume they're probably ok, and not the cause of the problem. Also checked the resistance to ground of all three (Yellow, Black and Red) leads going into well. All in the megohm range, so ok also.
My guess is that the motor is overheating and drawing excess current.
Is this correct? Are there any other possible explanations?
What are my options? What would cause this - the pump is about 10 years old.