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 o f lead pump f unction will take place. It is not possible to set this parameter to options
other that
Off
[0] if par. 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 command Alternation of the lead pump function will take place at an external command signal or a pre-pro-
grammed event. See par. 25-51
Alternation Event
for available options.
[3] At staging or command Alternation of the variable speed (lead) pump will take place at staging or the “At Command” signal.
(See above.)
NB!
It is not possible to select other than
Off
[0] if par. 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 par. 25-50
Lead Pump Alternation
. If an Alternation Event is selected, the alter-
nation 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 In-
puts
.
[1] Alternation Time Interval Alternation takes place every time par. 25-52
Alternation Time Interval
, expires.
[2] Sleep Mode Alternation takes place each time the lead pump goes into sleep mode. par. 20-23
Setpoint 3
must
be set to
Sleep Mode
[1] or an external signal applied for this function.
[3] Predefined Time Alternation takes place at a defined time of the day. If par. 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 h] If
Alternation Time Interval
[1] option in par. 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 par. 25-53
Alternation Timer Value
).
25-53 Alternation Timer Value
Range: Function:
0 N/A* [0 - 0 N/A] Readout parameter for the Alternation Time Interval value set in par. 25-52
Alternation Time In-
terval
.
25-54 Alternation Predefined Time
Range: Function:
Application
dependent*
[Application dependant] If option
Predefined Time
[3] in par. 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
®
HVAC Drive Programming Guide 3 Parameter Description
MG.11.C9.02 - VLT
®
is a registered Danfoss trademark
249
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