Danfoss VLT HVAC Drive FC 102 Programming Manual page 199

Parameter Descriptions
25-50 Lead Pump Alternation
Option: Function:
[0] Off No alternation of lead pump function takes
place. It is not possible to set this parameter to
*
options other that [0] Off if
parameter 25-02 Motor Start is set other than [0]
Direct on Line.
[1] At staging Alternation of the lead pump function takes
place when staging another pump.
[2] At Alternation of the lead pump function takes
command place at an external command signal or a pre-
programmed event. See
parameter 25-51 Alternation Event for available
options.
[3] At staging Alternation of the variable speed (lead) pump
or takes place at staging or the At command
command signal (see above).
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 Alternation takes place every time
Time parameter 25-52 Alternation Time Interval
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 must be applied for
this function.
[3] Predefined Alternation takes place at a defined time of the
Time 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).
MG11CE02
Programming Guide
25-52 Alternation Time Interval
Range:
24
h 999 h]
*
25-53 Alternation Timer Value
Range:
0 [0 - 7 ] Readout parameter for the alternation time interval
*
25-54 Alternation Predefined Time
Range:
Size
related
*
25-55 Alternate if Load < 50%
Option:
[0] Disabled The lead pump alternation takes place at any
[1] Enabled The lead pump function is alternated only if the
*
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Function:
[1 - 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).
Function:
value set in parameter 25-52 Alternation Time
Interval.
Function:
[ 0 - If selecting [3] Predefined Time in
0 ] 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
equal size.
pump capacity.
number of pumps running are providing less
than 50% of total pump capacity.
3 3
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