466 Rockwell Automation Publication 750-PM001N-EN-P - February 2017
Appendix C Application Notes
Pump Off Control Outlines
Automatic /Position Baseline Set
The following steps are a general outline of how the initial Pump Off control is
configured in the PowerFlex 753. The default configuration uses the down stroke
torque with P1187 [Pump Off Config] set to 0 “Automatic” or 1 “Position” and
P1190 [Pump Off Control] set to 1 “Baseline Set.”
Set Base Speed Command
A commanded speed setting is chosen based on well characteristics, which
produces the desired pump performance, most of the time. Pump off control is
then configured to maintain acceptable pump performance when conditions
temporarily change.
1. Pump off control requires the drive to be “At Speed.” Check P935 [Drive
Status 1] Bit 8 to verify this operating condition.
2. When P935 [Drive Status 1] Bit 8 “At Speed” = 1, the internal pump jack
at speed bit is set and the current speed command is saved.
3. The next ten down stroke torques are sampled and summed.
4. The average of the down stroke torques is saved as the baseline for the
current speed.
5. P1191 [Pump Off Status] Bit 6 “Pump Stable” = 1.
When Bit 6 = 0, the drive is averaging a new baseline torque.
6. The pump jack is running under normal conditions.
7. While running under normal conditions, every fifth stroke is compared
against the baseline to check for a pump off condition. The stroke count
can be monitored in test point TP 2043.
Change in Cycle Torque
If the cycle torque sample is less than or greater than the fixed setpoint by
the percentage set in P1195 [Pump Off Level], the following occurs:
• P1191 [Pump Off Status] Bit 5 “PumpOff Alarm”= 1
• The drive waits for a second sample
If the second sample is also less than or greater than the fixed setpoint by
the percentage set in P1195 [Pump Off Level], a Pump Off condition is
detected.
Run At Reduced Speed
When a Pump Off condition exists, and P1189 [Pump Off Action] is set
to 0 “Change Speed,” the percentage set in P1196 [Pump Off Speed]
lowers the commanded speed.
Reduced Speed = Commanded Speed - (Commanded Speed x P1196)
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