Danfoss VLT FC 100 Series Programming Manual page 196

Parameter Description
25-50 Lead Pump Alternation
Option: Function:
Lead pump alternation equalizes the use of
pumps by periodically changing the pump
that is speed controlled. This ensures that
pumps are equally used over time.
Alternation equalizes the usage of pumps by
always choosing the pump with the lowest
number of used hours to stage on next.
[0] OFF No alternation of lead pump function will
*
take place. It is not possible to set this
parameter to options other that Off [0] if
25-02 Motor Start is set other than Direct on
Line [0].
[1] At staging Alternation of the lead pump function will
take place when staging another pump.
[2] At Alternation of the lead pump function will
command take place at an external command signal or
a pre-programmed event. See
25-51 Alternation Event for available options.
[3] At staging Alternation of the variable-speed (lead) pump
or com. will take place at staging or the "At
Command" signal. (See above.)
NOTE!
It is not possible to select other than Off [0] if 25-05 Fixed
Lead Pump is set to Yes [1].
25-51 Alternation Event
Option: Function:
This parameter is only active if the options At
Command [2] or At Staging or Command [3]
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 Lead Pump Alternation [121] 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 Sleep Mode [1] 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
®
VLT HVAC Drive Programming Guide
25-51 Alternation Event
Option:
25-52 Alternation Time Interval
Range:
24 h
25-53 Alternation Timer Value
Range:
0
25-54 Alternation Predefined Time
Range:
Size related
25-55 Alternate if Load < 50%
Option:
[0]
[1]
NOTE!
Only valid if 25-50 Lead Pump Alternation is different from
Off [0].
MG11CD22 - VLT ® is a registered Danfoss trademark
Function:
the specified time. Default time is midnight
(00:00 or 12:00 AM depending on the time
format).
Function:
[1 - 999 If Alternation Time Interval [1] 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).
Function:
[0 - 0 ] Readout parameter for the Alternation Time
*
Interval value set in 25-52 Alternation Time Interval.
[ 0 - 0 ]
*
Function:
If Alternation If Capacity <50% is enabled, the
pump alternation can only occurs 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.
Disabled The lead pump alternation will take place at any
pump capacity.
Enabled The lead pump function will be alternated only if
*
the numbers of pumps running are providing less
than 50% of total pump capacity.
Function:
× 100 %
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