Rockwell Automation 21G PowerFlex 750-Series AC Drives Programming Manual - Manual (Page 463)

Rockwell Automation Publication 750-PM001J-EN-P - October 2014 463
Application Notes Appendix B
Pump Off Function Overview
The Pump Off function is used to change the speed of or stop the pump jack
automatically based on torque feedback from the motor. This function is useful
for maximizing well production and reducing mechanical wear.
Pump Off can be detected in one of two ways that are selected by P1187 [Pump
Off Config].
• Down Stroke Torque method: Setting 0 “Automatic” or 1 “Position”
The pump jack down stroke torque is based on a detected waveform.
• Cycle Torque method: Setting 2 “Cycle”
The pump jack down stroke torque is based on a full pump stroke cycle.
Setup
To use the Pump Off feature, the drive must operate in flux vector (FV) control
mode. This mode requires entering motor nameplate data and completing a
motor autotune routine. Gearbox ratio and sheave size data are also required.
Pump off control can be set to use a torque baseline, which is created when the
drive is first run or from a fixed set point. The fixed set point is useful if the drive
cannot detect a signature waveform due to well conditions. The drive does not
create a set point that is based on what could be a pump off condition.
The down stroke torque can change position on some wells due to slippage in the
system. In these cases, the peaks and valleys of the torque waveform move enough
that the position reconnect does not work properly. This can be seen on the
position test point in that the position continues to reset early. To work on these
pumps, the torque waveform over one cycle is averaged.