Danfoss VLT FC 102 Programming Manual page 246

Parameter Descriptions
25-51 Alternation Event
Option:
3 3
[0] External
*
[1] Alternation
Time Interval
[2] Sleep Mode
[3] Predefined
Time
25-52 Alternation Time Interval
Range:
24 h
*
25-53 Alternation Timer Value
Range:
0
*
244
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.
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.
Alternation takes place every time
parameter 25-52 Alternation Time
Interval expires.
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.
Alternation takes place at a defined
time of the day. If
parameter 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).
Function:
[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.
Function:
[0 - 7 ] Readout parameter for the
alternation time interval value set in
parameter 25-52 Alternation Time
Interval.
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VLT HVAC Drive FC 102
25-54 Alternation Predefined Time
Range:
Size
related
*
25-55 Alternate if Load < 50%
Option:
[0]
[1]
*
Function:
[ 0 - 0 ] If selecting [3] Predefined Time in
parameter 25-51 Alternation Event,
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).
Function:
NOTICE
Only valid if
parameter 25-50 Lead Pump
Alternation is different from [0]
Off.
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).
N
RUNNING
Capacity = × 100 %
N
TOTAL
For the basic cascade controller, all
pumps are of equal size.
Disabled The lead pump alternation takes
place at any pump capacity.
Enabled The lead pump function is
alternated only if the number of
pumps running are providing less
than 50% of total pump capacity.
M0010001