Pentair PID-50 over current error but pump out works fine

[struman]

Hi,

I have a Pentair PID-50 with a 3 phase 5hp Pentair P43B0050A3. Deep well ~1000ft

About four months ago, the PID died on its 4th anniversary - ground fault. New PID just started giving over current fault and slams off ~17-20psi seconds after restarting. However, the pump out feature works fine...and will run as long as we let it. Reset breakers, checked pressure sensor at tank, input voltage (240) and amperage readings (during pump out). Spoke with tech support and they said it's probably a bad PID...

Installed new PID this morning...same result - ugh...

If there's an issue with the motor, why would pump out work fine? Any other ideas?

thank you
Steve

 

[Valveman]

First, I am sorry for your problem. I will try to help. The real problem is so many things can go wrong with a VFD or variable speed pump system that being out of water could be caused by any number of things. With the expense of working on a 1000' deep well, I would pump into a cistern. Using a 3HP, 7GPM pump filling a cistern would take a lot of wear and tear off the well pump. Then a booster pump in the cistern could supply all the water and pressure the house needs while being much less expensive and easier to work on when needed. More on the VFD coming.

 

[Sponsor]

 

[Valveman]

Studying the manual for the PID50 it says 1000' of wire maximum, which is what you have. This is because of the "reflective wave" a VFD produces, that causes the longer wire to amplify the voltage. A 230V supply to the PID can cause over 1000V at the motor with the long wires. Both the windings in the motor as well as the drop wire in the well is only rated to 600V. A lot of voltage leaks out and can cause a short. The max setting for the Service Factor on a 5HP is 17.8 amps. If amps are already at 17.8, you will probably have to increase them to try and keep the pump running.

Troubleshooting an overcurrent fault says.....
Shorted output. Could be caused by the high voltage from the VFD.
Damaged wire insulation. That is what causes the short and is caused by the high voltage.
Missing phase in motor. Caused by the high rate of failure on turn to turn passes in a motor controlled by a VFD.
Wrong service factor amps. 17.8 is max

Runout says it only goes to 45 hertz unless you program it to go to 60 hertz. I would do that and see if the amps are high.
Probably saved a ton of money on the wire using the VFD, which is one of the selling features. But you usually end up paying for it in the long run.