Danfoss VLT CDS 303 User Manual

25-47 Destaging Speed [Hz]
Option: Function:
Figure 6.35 Destaging Speed
6.14.4 25-5* Alternation Settings
Parameters for dening the conditions for alternation of
the variable speed compressor (lead), if selected as part of
the control strategy.
25-50 Lead Compressor Alternation
Option: Function:
Lead compressor alternation equalizes the use
of compressors by periodically changing the
compressor that is speed controlled. This
ensures that compressors are equally used over
time. Alternation equalizes the usage of
compressors by always choosing the
compressor with the lowest number of used
hours to stage on next.
[0]
*
O No alternation of lead compressor function will
take place. It is not possible to set this
parameter to options other than [0] O if
parameter 25-02 Motor Start is set other than
[0] Direct on Line.
NOTICE!
It is not possible to select other than [0]
O if parameter 25-05 Fixed Lead
Compressor is set to [1] Yes.
[1] At Staging Alternation of the lead compressor function
will take place when staging another
compressor.
[2] At
Command
Alternation of the lead compressor function
will take place at an external command signal
or a pre-programmed event. See
parameter 25-51 Alternation Event for available
options.
25-50 Lead Compressor Alternation
Option: Function:
[3] At Staging
or at
Command
Alternation of the variable speed (lead)
compressor will take place at staging or the “At
Command” signal (See above).
25-51 Alternation Event
Option: Function:
This parameter is only active if the options [2]
At Command or [3] At Staging or Command
have been selected in parameter 25-50 Lead
Compressor Alternation. If an Alternation Event
is selected, the alternation of lead compressor
takes place every time the event occurs.
[0]
*
External Takes place when a signal is applied to one of
the digital inputs on the terminal strip and
this input has been assigned to [121] Lead
Compressor Alternation in parameter group
5-1* Digital Inputs.
[1] Alternation
Time
Interval
Takes place every time
parameter 25-52 Alternation Time Interval
expires.
25-52 Alternation Time Interval
Range: Function:
24
h*
[1 –
999 h]
If [1] Alternation Time Interval option in
parameter 25-51 Alternation Event is selected, the
alternation of the variable speed compressor
takes place every time the Alternation Time
Interval expires (can be checked out in
parameter 25-53 Alternation Timer Value).
25-53 Alternation Time Value
Option: Function:
0 N/A Readout parameter for the Alternation Time Interval
value set in parameter 25-52 Alternation Time Interval.
25-55 Alternation if Capacity < 50%
Option: Function:
[0] Disabled
[1] * Enabled If Alternation If Capacity <50% is enabled, the
compressor alternation can only occur if the
capacity is equal to or below 50%. The capacity
calculation is the ratio of running compressors
(including the variable speed compressor) to the
total number of available compressors (including
variable speed compressor, but not those
interlocked).
Capacity = 
NRunning
NTotal
 × 100 %
For the Basic Cascade Controller all compressors
are equal size.
Disabled [0]: The lead compressor alternation will
take place at any compressor capacity.
Parameter Descriptions
VLT
®
Compressor Drives CDS 302/CDS 303
118 Danfoss A/S © Rev. 2013-07-03 All rights reserved. MG34M422
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Danfoss VLT CDS 303 Specifications

General

Brand	Danfoss
Model	VLT CDS 303
Category	DC Drives
Language	English