Danfoss VLT Series Programming Manual page 184

Parameter Description
25-47 Destaging Speed [Hz]
Range: Function:
0.0 [0.0 Readout of the below calculated value for
Hz - 0.0 Destaging Speed. When removing a fixed speed
*
Hz] pump, in order to prevent an undershoot of
pressure, the variable speed pump ramps up to a
higher speed. When the variable speed pump
reaches the "Destaging Speed" the fixed speed
pump is destaged. Destaging Speed is calculated
based on 25-43 Destaging Threshold, and
4-14 Motor Speed High Limit [Hz].
Destaging Speed is calculated with the following
formula:
DESTAGE %
DESTAGE = HIGH
where n is Motor Speed High Limit and
HIGH
n is the value of Destaging Threshold.
DESTAGE100%
Motor speed
high limit
Destaging
speed
Motor speed
low limit
Controlled stop
command
activated
Motor speed
high limit
Fixed speed
pump
Destaging
speed
Motor speed
low limit
Motor speed
high limit
Destaging
speed
Motor speed
low limit
3.23.4 25-5* Alternation Settings
Parameters for defining the conditions for alternation of
the variable speed pump (lead), if selected as part of the
control strategy.
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.
®
VLT HVAC Drive Programming Guide
100
Variable speed
pump
Seconds
Seconds
Fixed speed
pump
Seconds
®
MG.11.CC.02 - VLT is a registered Danfoss trademark
25-50 Lead Pump Alternation
Option: Function:
[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 will take place at staging or the "At
command 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 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 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).
25-53 Alternation Timer Value
Range: Function:
0 [0 - 0 ] Readout parameter for the Alternation Time
*
Interval value set in 25-52 Alternation Time Interval.
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