Danfoss VLT AQUA Drive FC 202 Programming Manual page 183

Parameter Description
25-55 Alternate if Load < 50%
Option: Function:
If [1] Enabled is selected, the pump alternation can
only occur if the capacity is equal to or below 50%.
The capacity calculation is the ratio of running
pumps (including the variable speed pump) to the
total number of available pumps (including variable
speed pump, but not those interlocked).
NRUNNING
Capacity =
NTOTAL
For the Basic cascade controller all pumps are
equal size.
[0] Disabled The lead pump alternation will take place at any
pump capacity.
[1] Enabled The lead pump function will be alternated only if
the numbers of pumps running are providing less
than 50% of total pump capacity.
NOTICE
Only valid if parameter 25-50 Lead Pump Alternation is
different from [0] Off.
25-56 Staging Mode at Alternation
Option: Function:
[0] Slow
[1] Quick This parameter is only active if the option selected in
parameter 25-50 Lead Pump Alternation is different
from [0] Off.
2 types of staging and destaging of pumps are
possible. Slow transfer makes staging and destaging
smooth. Quick Transfer makes staging and destaging
as fast as possible; the variable speed pump is just cut
out (coasted).
[0] Slow: At alternation, the variable speed pump is
ramped up to maximum speed and then ramped
down to a stand still.
[1] Quick: At alternation, the variable speed pump is
ramped up to maximum speed and then coasted to
stand still.
Illustration 3.85 and Illustration 3.86 show Alternation
in both Quick and Slow configurations.
Alternation command/PID stops
f
MAX
Destaging freq.
f
MIN.
f
MAX
Staging freq.
Mains operation
Illustration 3.85 Slow Configuration
MG20O702
Programming Guide
× 100%
Mains operation
Time
PID contr.
starts
5 s Time
Danfoss A/S © Rev. 2014-01-21 All rights reserved.
Coast
200ms-2s (default 500ns)5 s
100ms
Illustration 3.86 Quick Configuration
25-58 Run Next Pump Delay
Range: Function:
0.1 s [0.1 - This parameter is only active if the option
*
5 s] selected in parameter 25-50 Lead Pump
Alternation, is different from [0] Off.
This parameter sets the time between stopping
the old variable speed pump and starting
another pump as a new variable speed pump.
Refer to 25-56 Staging Mode at Alternation, the
illustration for description of staging and
alternation.
25-59 Run on Mains Delay
Range: Function:
0.5 s [ par. This parameter is only active if the option
*
25-58 - 5 selected in parameter 25-50 Lead Pump
s] Alternation, is different from [0] Off.
This parameter sets the time between
stopping the old variable speed pump and
starting this pump as a new fixed speed
pump. Refer to Illustration 3.85 for description
of staging and alternation.
3.22.5 25-8* Status
Readout parameters informing about the operating status
of the cascade controller and the pumps controlled.
25-80 Cascade Status
Range: Function:
0 [0 - 25 ] Read out of the status of the cascade controller.
*
Mains operation
Time
Time
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