Danfoss VLT AQUA Drive FC 200 Programming Manual page 181

Parameter Description
25-51 Alternation Event
Option: Function:
This parameter is only active if the options [2]
At Command or [3] At Staging or Command
have been selected in 25-50 Lead Pump
Alternation. If an alternation event is selected,
the alternation of lead pump takes place every
time the event occurs.
[0] External Alternation takes place when a signal is
applied to one of the digital inputs on the
terminal strip and this input has been
assigned to [121] Lead Pump Alternation in
parameter group 5-1*, Digital Inputs.
[1] Alternation Alternation takes place every time
Time Interval 25-52 Alternation Time Interval expires.
[2] Sleep Mode Alternation takes place each time the lead
pump goes into Sleep mode. 20-23 Setpoint 3
must be set to [1] Sleep Mode or an external
signal applied for this function.
[3] Predefined Alternation takes place at a defined time of
Time the day. If 25-54 Alternation Predefined Time is
set, the alternation is carried out every day at
the specified time. Default time is midnight
(00:00 or 12:00AM depending on the time
format).
25-52 Alternation Time Interval
Range: Function:
24 h [1 - 999 If [1] Alternation Time Interval option in
*
h] 25-51 Alternation Event is selected, the
alternation of the variable-speed pump takes
place every time the Alternation Time Interval
expires (can be checked out in
25-53 Alternation Timer Value).
25-53 Alternation Timer Value
Range: Function:
0 [0 - 0 ] Readout parameter for the Alternation Time
*
Interval value set in 25-52 Alternation Time Interval.
25-54 Alternation Predefined Time
Range: Function:
Size [ 0 - If option [3] Predefined Time in
related 0 ] 25-51 Alternation Event is selected, the
*
variable-speed pump alternation is carried
out every day at the specified time set in
Alternation Predefined Time. Default time is
midnight (00:00 or 12:00AM depending on
the time format).
®
VLT AQUA Drive Programming Guide
[0] Disabled The lead pump alternation will take place at any
[1] Enabled The lead pump function will be alternated only if
NOTICE!
Only valid if 25-50 Lead Pump Alternation is different from
[0] Off.
[0] Slow
[1] Quick This parameter is only active if the option selected in
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MG20O622 - VLT is a registered Danfoss trademark
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).
N RUNNING
Capacity =
N TOTAL
For the Basic Cascade Controller, all pumps are
equal size.
pump capacity.
the numbers of pumps running are providing less
than 50% of total pump capacity.
25-56 Staging Mode at Alternation
Option: Function:
25-50 Lead Pump Alternation is different from [0] Off.
Two types of staging and de-staging of pumps are
possible. Slow transfer makes staging and de-staging
smooth. Quick transfer makes staging and de-staging
as fast as possible; the variable-speed pump is simply
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.
Figure 3.79 and Figure 3.80 show Alternation in both
Quick and Slow configurations.
Alternation command/PID stops
f
MAX
Destaging freq.
f
MIN.
f
MAX
Staging freq.
Mains operation
Figure 3.79 Slow Configuration
× 100 %
Mains operation
Time
PID contr.
starts
5 s Time
3-155
3 3