Rockwell Automation Publication 750-PM001N-EN-P - February 2017 469
Application Notes Appendix C
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], 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 baseline by the
percentage set in P1195 [Pump Off Level], a Pump Off condition is
detected.
Execute Pump Off Action
When a Pump Off condition exists, the drive follows the setting of P1189
[Pump Off Action]. The process starts over at Step 1
in this sequence and
five strokes occur to allow the pump to settle out.
Whenever the operator changes the base speed command, the process starts over
at Step 1
in this sequence.
When P1187 [Pump Off Config] is set to 2 “Cycle,” the full stroke torque is used
for pump off detection. A separate position counter is enabled, which uses the
gear ratio and speed feedback to create a position. The gear ratio must be set
correctly for this action to work.
• The position increments every 2 ms based on output frequency. The
torque is added to a buffer and a counter increments.
• When the position counter reaches 10,000, the counter is reset to 0. The
torque buffer is divided by the counter to create the average torque for the
cycle.
• This torque is the full cycle torque and is then used as the down stroke
torque was used in baseline set detection.
Table 24 - PowerFlex 753 Pump Off Test Points
Test Point Description
TP 2031 Motor Torque in Pump Off
TP 2032 Top Of Stroke in Pump Off
TP 2033 POSITION1 in Pump Off
TP 2034 POSITION2 in Pump Off
TP 2035 POSITION3 in Pump Off
TP 2036 POSITION4 in Pump Off
TP 2037 POSITION5 in Pump Off
TP 2038 Active Position in Pump Off
TP 2039 Position State in Pump Off
TP 2040 Heavily filter torque for position detection in Pump Off
TP 2041 PumpJack control state in Pump Off
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