Danfoss vlt FC 102 - Page 246

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 parameter 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 1 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
Time Interval
Alternation takes place every time
parameter 25-52 Alternation Time
Interval expires.
[2] Sleep Mode Alternation takes place each time
the lead pump goes into sleep
mode. Set parameter 20-23 Setpoint
3 to [1] Sleep Mode or apply an
external signal for this function.
[3] Predened
Time
Alternation takes place at a dened
time of the day. If
parameter 25-54 Alternation
Predened Time is set, the
alternation is carried out every day
at the specied 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 h] If selecting [1] Alternation Time
Interval in
parameter 25-51 Alternation Event,
the alternation of the variable-
speed pump takes place every time
the alternation time interval expires
(can be checked in
parameter 25-53 Alternation Timer
Value). The timer pauses when the
frequency converter is not running.
25-53 Alternation Timer Value
Range: Function:
0* [0 - 7 ] Readout parameter for the
alternation time interval value set in
parameter 25-52 Alternation Time
Interval.
25-54 Alternation Predened Time
Range: Function:
Size
related*
[ 0 - 0 ] If selecting [3] Predened Time in
parameter 25-51 Alternation Event,
the variable-speed pump
alternation is carried out every day
at the specied time set in
alternation predened time. Default
time is midnight (00:00 or 12:00AM
depending on the time format).
25-55 Alternate if Load < 50%
Option: Function:
NOTICE
Only valid if
parameter 25-50 Lead Pump
Alternation is dierent from [0]
O.
If selecting [1] Enabled, 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 that are interlocked).
Capacity = 
N
RUNNING
N
TOTAL
 × 100 %
For the basic cascade controller, all
pumps are of equal size.
[0] Disabled The lead pump alternation takes
place at any pump capacity.
[1] * Enabled The lead pump function is
alternated only if the number of
pumps running are providing less
than 50% of total pump capacity.
Parameter Descriptions
VLT
®
HVAC Drive FC 102
244 Danfoss A/S © 10/2019 All rights reserved. M0010001
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