6.14.1 25-0* System Settings
Parameters related to control principles and conguration
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/o
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.
NOTICE!
This parameter can only be [1] Enabled, if
parameter 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 parameter 25-02 Motor Start is set to an option
other than [0] Direct on Line, then
parameter 25-50 Lead Compressor Alternation is
automatically set to the default of [0] Direct on
Line.
[0]
*
Direct
on Line
Each xed speed compressor is connected to line
directly via a contactor.
[1] Soft
starter
Each xed speed compressor is connected to line
via a soft starter.
25-04 Compressor Cycling
Option: Function:
To provide equal hours of operation with xed
speed compressors, the compressor use can be
cycled. The selection of compressor cycling is
either “rst in – last out” or equal running hours
for each compressor.
[0] * Disabled The xed speed compressors will be connected in
the order 1 – 2 – 3 and disconnected in the order
3 – 2 – 1. (First in – last out)
25-04 Compressor Cycling
Option: Function:
[1] Enabled The xed speed compressors will be connected/
disconnected to have equal running hours for
each compressor.
25-05 Fixed Lead Compressor
Option: 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.
[0] 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).
[1] * Yes The lead compressor will be xed (no alternation) and
connected directly to the frequency converter. The
25-50 Lead Compressor Alternation is automatically set
to [0] O. Built-in relays Relay 1 and Relay 2 can be
assigned to separate xed speed compressors. In total
three compressors can be controlled by the frequency
converter.
25-06 Number of Compressors
Option: 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 xed
speed compressors (lag compressors) are
controlled by the two built in relays, three
compressors can be controlled. If both the
variable speed and xed speed compressors
are to be controlled by built-in relays, only
two compressors can be connected.
[0]
*
2
compressors
If 25-05 Fixed Lead Compressor is set to [0]
No: one variable speed compressor and one
xed 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 xed speed compressor
controlled by built-in relay
[1] 3
compressors
[1] 3 Compressors: One lead compressor, see
25-05 Fixed Lead Compressor. Two xed speed
compressors controlled by built-in relays.
Parameter Descriptions Operating Instructions
MG34M422 Danfoss A/S © Rev. 2013-07-03 All rights reserved. 113
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