Rockwell Automation 21G PowerFlex 750-Series AC Drives Programming Manual User Manual
Page 471
Rockwell Automation Publication 750-PM001J-EN-P - October 2014
471
Application Notes
Appendix B
8.
When the reduced speed is reached, P935 [Drive Status 1] Bit 8 “At
Speed” = 1, the next ten down stroke torques are sampled and added
together.
9.
The average of the down stroke torques is saved as the baseline for the new
speed. P1191 [Pump Off Status] Bit 6 “Pump Stable” is reset.
10.
The pump jack runs at the reduced speed for the length of time set in
P1197 [Pump Off Time] then the pump jack resumes pumping at the base
speed command. (
in this sequence.)
If P1189 [Pump Off Action] is set to 3 “Stop After 2," go to
Step 11
.
Whenever the operator changes the base speed command, the process
starts over at
in this sequence. This action does not apply to speed
changes that are triggered by P1189 [Pump Off Action] when a pump off
condition is detected.
11.
While running at the first reduced Pump Off Speed, every fifth stroke is
compared to the new baseline for a pump off condition.
If the down-stroke torque samples remain stable during the time set in
P1197 [Pump Off Time], the commanded speed returns to the original
base speed and down stroke torque samples are compared against the
original baseline. (
If two down stroke torque samples are less than or greater than the new
baseline by the percentage set in P1195 [Pump Off Level], the Pump Off
condition persists and the percentage set in P1196 [Pump Off Speed]
lowers the commanded speed a second time.
12.
When the second reduced speed is reached, P935 [Drive Status 1] Bit 8
“At Speed” = 1, the next ten down stroke torques are sampled and added
together.
13.
The average of the down stroke torques is saved as the baseline for the
second new speed. P1191 [Pump Off Status] Bit 6 “Pump Stable” is reset.
14.
The pump jack runs at the second reduced speed for the length of time set
in P1197 [Pump Off Time] and resumes pumping at the base speed
command. (
in this sequence.)
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 commanded speed returns to the original
base speed and down stroke torque samples are compared against the
original baseline. (
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 Pump Off
condition persists and the drive stops for the length of time set in P353
[Sleep Time].