Danfoss VLT FC 102 Programming Manual page 245

Parameter Descriptions
25-47 Destaging Speed [Hz]
Range: Function:
0 Hz [0 - 0 Hz] Readout of the calculated value for
*
destaging speed. When removing a
fixed speed pump 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 parameter 25-43 Destaging
Threshold and parameter 4-14 Motor
Speed High Limit [Hz].
Destaging speed is calculated with
the following formula:
DESTAGE = HIGH
where n
limit and n
destaging threshold.
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
Illustration 3.86 Destaging Speed
M0010001
Programming Guide
DESTAGE %
100
is motor speed high
HIGH
is the value of
DESTAGE100%
Variable speed
pump
Seconds
Seconds
Fixed speed
pump
Seconds
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3.23.4 25-5* Alternation Settings
Parameters for defining the conditions for alternation of
the variable-speed pump (lead), if selected as control
strategy.
25-50 Lead Pump Alternation
Option: Function:
NOTICE
If parameter 25-05 Fixed Lead
Pump is set to [1] Yes, it is only
possible to select [0] Off.
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 selecting the
pump with the lowest number of
hours run to stage on next.
[0] Off No alternation of lead pump
*
function takes place. It is not
possible to set this parameter to
options other than [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 command Alternation of the lead pump
function takes place at an external
command signal or a pre-
programmed event. See
parameter 25-51 Alternation Event
for available options.
[3] At staging or Alternation of the variable-speed
command (lead) pump takes place at staging
or according to [2] At command.
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