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9.3
Follow Lead - Conditions for De-staging Lag Drives
1.
Feedback is above the setpoint PID-11 (PID Ref 1 Set).
2.
Output Frequency of the Main drive reached the De-stage frequency AP1-70 (Destage Freq 1) for the Lag
drive.
3.
The De-Stage delay time AP1-54 (Destage DT) has expired.
9.4
Follow Lead - De-staging Details
Three drives/motors/pumps are running and Drive 3 is the Main PI controlled drive. The feedback has increased to
a level above the setpoint. When the three conditions are met ((feedback above setpoint, operating frequency
reaches de-staging frequency and the delay time has expired), the Main drive decelerates and eventually stops.
With FILO operation, Drive 3 (M3) is the first to stop. Since Drive 3 (M3) is the Main PI controlled drive, a shift
occurs making Drive 2 (M2) the Main drive. As de-staging continues, Drive 2 (M2) decelerates and stops. Since
Drive 2 is now the Main PI controlled drive, a shift occurs making Drive 1 (M1) the Main drive. At this time, Drive 1
(M1) is operating as the Main drive and continues PI control. If the feedback continues to be above the setpoint, it
will also eventually stop or go into Sleep mode, if set. This is the
Last Out
for the FILO setting.
Other Conditions
Priority - The drive priority AP1-45 (Curr. Prty 1) can be viewed as the running order. The 4 digits (0321) represent
the first 4 drives. Since only 3 are in the example Lead/Lag system, it shows as 0321. The run priority for each drive
is also shown on each drive’s LCD at the top center of the display. See
Parameter AP1-44, Lag Pump Run. This is simply the number of Lag drives (only) running and changes as Lag
drives are operated.
The actual acceleration/deceleration times of the output frequency will vary based on a combination of PID-25 (PID
P-Gain 1) of the drive and DRV-03 (Acc Time), DRV-04 (Dec Time) in each drive.
Lead (+) Change - The Lead (+) drive can change if the Lead (+) drive trips or is manually stopped. Run priority will
change on Start/Stops and Sleep mode. See
Section 16, Lead Change.
Summary of Contents for RSi H2P Series
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