Danfoss VLT CDS302 Operating Instructions Manual page 109

Parameter Descriptions
6.14.1 25-0* System Settings
Parameters related to control principles and configuration
of the system.
25-00 Cascade Controller
Option: Function:
For operation of multiple devices (compressor)
systems where capacity is adapted to actual load
by means of speed control combined with on/off
control of the devices. For simplicity only
compressor systems are described.
[0] Disabled The Cascade Controller is not active. All built-in
*
relays assigned to compressor motors in the
cascade function will be de-energized. If a
variable speed compressor is connected to the
frequency converter directly (not controlled by a
built-in relay), this compressor will be controlled
as a single compressor system.
[1] Enabled The Cascade Controller is active and will stage/
destage compressors according to load on the
system.
NOTE
This parameter can only be [1] Enabled, if 22-75 Short Cycle
Protection is set to [0] Disabled.
25-02 Motor Start
Option: Function:
Motors are connected to the mains directly with
a contactor or with a soft starter. When the
value of 25-02 Motor Start is set to an option
other than [0] Direct on Line, then 25-50 Lead
Compressor Alternation is automatically set to
the default of [0] Direct on Line.
[0] Direct on Each fixed speed compressor is connected to
*
Line line directly via a contactor.
[1] Soft Each fixed speed compressor is connected to
starter line via a soft starter.
25-04 Compressor Cycling
Option: Function:
To provide equal hours of operation with fixed
speed compressors, the compressor use can be
cycled. The selection of compressor cycling is
either "first in – last out" or equal running hours
for each compressor.
[0] Disabled The fixed speed compressors will be connected in
*
the order 1 – 2 – 3 and disconnected in the
order 3 – 2 – 1. (First in – last out)
[1] Enabled The fixed speed compressors will be connected/
disconnected to have equal running hours for
each compressor.
MG34M302 - VLT
®
Operating Instructions VLT
25-05 Fixed Lead Compressor
Option:
[0]
[1]
*
25-06 Number of Compressors
Option:
[0]
*
[1]
6.14.2 25-2* Bandwidth Manager
Parameters for setting the bandwidth within which the
pressure/temperature will be allowed to operate before
staging/destaging fixed speed compressors. Also includes
various timers to stabilize the control.
®
is a registered Danfoss trademark/Commercial Compressor
CDS302 and CDS303
Function:
Fixed Lead Compressor means that the variable speed
compressor is connected directly to the frequency
converter and if a contactor is applied between
frequency converter and compressor, this contactor
will not be controlled by the frequency converter.
No The lead compressor function can alternate between
the compressors controlled by the two built in relays.
One compressor must be connected to the built-in
RELAY 1, and the other compressor to RELAY 2. The
compressor function (Cascade Compressor1 and
Cascade Compressor2) will automatically be assigned
to the relays (maximum two compressors can in this
case be controlled from the frequency converter).
Yes The lead compressor will be fixed (no alternation) and
connected directly to the frequency converter. The
25-50 Lead Compressor Alternation is automatically set
to [0] Off. Built-in relays Relay 1 and Relay 2 can be
assigned to separate fixed speed compressors. In total
three compressors can be controlled by the frequency
converter.
Function:
The number of compressors connected to
the Cascade Controller including the
variable speed compressor. If the variable
speed compressor is connected directly to
the frequency converter and the other fixed
speed compressors (lag compressors) are
controlled by the two built in relays, three
compressors can be controlled. If both the
variable speed and fixed speed compressors
are to be controlled by built-in relays, only
two compressors can be connected.
2 If 25-05 Fixed Lead Compressor is set to [0]
compressors No: one variable speed compressor and one
fixed speed compressor; both controlled by
built in relay. If 25-05 Fixed Lead Compressor
is set to [1] Yes: one variable speed
compressor and one fixed speed
compressor controlled by built-in relay
3 [1] 3 Compressors: One lead compressor, see
compressors 25-05 Fixed Lead Compressor. Two fixed
speed compressors controlled by built-in
relays.
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