Rockwell Automation 21G PowerFlex 750-Series AC Drives Programming Manual User Manual
Page 472
472
Rockwell Automation Publication 750-PM001J-EN-P - October 2014
Appendix B
Application Notes
16.
When P353 [Sleep Time] expires, the pump jack restarts and runs under
normal conditions. (
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. (
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 looked at 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.
5.
While running under normal conditions, every fifth stroke is compared
against the baseline to check for a pump off condition.
Change in Down Stroke Torque
If the down-stroke torque sample is less than or greater than the baseline by
the percentage set in P1195 [Pump Off Level], P1191 [Pump Off Status]
Bit 5 “PumpOff Alarm”= 1 and the drive waits for a second sample.
If the second sample is also less than or greater than the baseline by the
percentage set in P1195 [Pump Off Level], a Pump Off condition is
detected.