I see that.
It would be possible to tell what size 3-phase motor is down there by measuring a winding resistance, even though we don't know the wire length or gauge. We could compensate for the feed wire resistances, as long as we can presume they are equal. I understand that does not tell the pump end size.
But Boycedrilling in reply #42 pointed to a document. The pump curve there would be for the system I am thinking. So that could be used to infer the pump end. While a curve like that might be roughly a 1.5 HP 60 Hz pump, I am thinking based on their graphs that the pump end associated with that number could be a 3/4 pump end. Let's say that it really does not seem that it could be a 2 HP pump end, so with that controller, the 1.5 setting would be as close as it could be chosen.
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Leeeson, what do you know about the well depth? Water about 100 ft down? If you want to determine what the motor size is, what we would need is that you put maybe 6 volts DC across two isolated motor wires, and measure the current drawn. At the same time, measure the voltage across the two terminals carrying the current, and measure the voltage from the un-connected wire and either of the two current-carrying wires. From those we can compute the resistance of a winding of the pump. Then compare that with values from table 22 of the AIM manual to figure out the motor size. For example, a 3 HP motor should have each winding 1.8 to 2.2 ohms.
I figure 6 volts would keep the current low enough, which I think would be low enough to not hurt anything. You could use I would say 1 to volts DC ... as long as you measure the voltage across the winding wires up top. I would not feel safe with higher voltage, but maybe I am too cautious.
You know that I am not a pro, but I think I can back up the math.