468 Rockwell Automation Publication 750-PM001N-EN-P - February 2017
Appendix C Application Notes
15. While running at the second reduced Pump Off Speed, every fifth stroke is
compared to the second new baseline for a persistent pump off condition.
If the down-stroke torque samples remain stable during the time set in
P1197 [Pump Off Time], the following occurs:
• The commanded speed returns to the original base speed
• The down stroke torque samples are compared against the original
baseline. (Step 6
in this sequence.)
If two down stroke samples are less than or greater than the second new
baseline by the percentage set in P1195 [Pump Off Level], the following
occurs:
• The Pump Off condition persists
• The drive stops for the length of time set in P353 [Sleep Time]
16. When P353 [Sleep Time] expires, the pump jack restarts and runs under
normal conditions. (Step 6
in this sequence.)
When P1189 [Pump Off Action] is set to 2 “Stop After 1,” the drive stops for the
length of time set in P353 [Sleep Time] after one reduction of speed. (Step 11
in
this sequence.)
When P1189 [Pump Off Action] is set to 1 “Always Stop,” the drive stops for the
length of time set in P353 [Sleep Time] at the first detection of a Pump Off
condition. When P353 [Sleep Time] expires, the pump jack restarts and runs
under normal conditions. (Step 6
in this sequence.)
When P1192 [Pump Cycle Store] does not change back to 0 “disable,” the drive
has not been able to detect a pump-jack torque signature waveform to use as a
baseline. A fixed set point is required to run the well. See the next section.
Cycle Torque Data Fixed Setpoint
The following is a general outline of how the initial Pump Off control is
configured in the PowerFlex 753. This configuration uses cycle torque data with
P1187 [Pump Off Config] set to 2 “Cycle” and P1190 [Pump Off Control] set
to 2 “Fixed Setpt.”
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. The At Speed
bit is no longer scrutinized until the speed command is changed or the
drive is stopped.
The next three strokes are used to allow the pump to settle out.
3. P1191 [Pump Off Status] Bit 6 “Pump Stable” = 1.
4. The pump jack is running under normal conditions.
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