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 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
par. 5-1*, Digital Inputs
.
[1]
Alternation Time Inter-
val
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, No-Flow Function
, 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
Alternation Event
, par. 25-51, is selected, the alternation of the variable
speed pump takes place every time the Alternation Time Interval expires (can be checked out in
Alternation Timer
Value
, par. 25-53).
25-53 Alternation Time Value
Option:
Function:
0 N/A
Readout parameter for the Alternation Time Interval value set in par. 25-52.
25-54 Alternation Predefined Time
Range:
Function:
00:00
*
[00:00 – 23:59]
If option
Predefined Time
[3] in
Alternation Event
, par. 25-51, 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).
25-55 Alternation if Capacity < 50%
Option:
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).
Capacity =
NRUNNING
NTOTAL
× 100 %
For the Basic Cascade Controller all pumps are equal size.
[0]
Disabled
The lead pump alternation will take place at any pump capacity.
[1]
*
Enabled
The lead pump function will be alternated only if the numbers of pumps running are providing less than 50%
of total pump capacity.
NB!
Only valid if
par. 25-50, Lead Pump Alternation
is different from
Off
[0].
3. Parameter Description
VLT
®
HVAC Drive Programming Guide
218
MG.11.C5.02 - VLT
®
is a registered Danfoss trademark
3