Lift station. Wet well level is a submersible pressure transmitter, 4-20 mA, into a MicroLogix 1400 with a 1762 IF4. Pump 2 got a new PowerFlex 755 last month, 25 HP. Since then the level jumps about 5 percent whenever pump 2 runs, quiet with pump 2 off. Pump 1 is on a soft starter and never bothers it.

I swapped the transmitter for the spare, no change, and a 2 s filter in the ladder hides most of it but the pump starts hunt because the level lags.

The signal pair runs in the same duct as the pump 2 motor leads I think. Should I just filter harder in the PLC?