44 CT-600-2
variable speed compressor (where used) is given a sufficiently high capacity request to force the slide valve to
the 100% position, which allows the speed regulation to be released.
Manual
The manual mode forces the compressor unit to run at a specific capacity. The unit will not regulate when
running in manual mode. To set a specific set point push the “Cap. Set button [2] and a numeric pop-up
window will appear. Insert the desired set point and push “enter”. The picture shows how the regulation
section will look when in manual mode. If the unit is not running, then the entered capacity must be above the
value for the minimum capacity to start.
Auto
When automatic mode is enabled the unit will start, stop and regulate automatically based on the output of
the chosen PID regulation. The user must adjust the regulator type and the desired setpoint in the parameter
section. A proper automatic regulation can only be achieved, when the PID regulator settings, various related
warning levels and the capacity limiter parameters are adjusted so, to give best possible regulation and
interaction between the PID regulator and the limiter functions, for the process which the ACP is part of.
When the unit is not running, the PID regulator will increase its output, as soon as the unit is ready and the
process value is above the setpoint (cooling mode). Once the PID output reaches the minimum capacity to
start, then the ACP LINK will start the first compressor and the PID ramp function will be enabled. The ramp
function makes it possible to control how fast the ACP will try to bring the process value to the level defined
by the setpoint. See more in section 10.11 regarding the PID regulator and related parameters.
Remote
The remote operating mode allows the capacity that the ACP delivers to be regulated from minimum to
maximum level with an external signal. This external capacity signal must be delivered by the customer as an
analog input to the electrical starter panel IO-module (see also section 11.1). When the unit is not running,
then the remote signal must exceed the level of the minimum capacity to start. The unit will stop when the
remote signal falls below 1/3 of the minimum capacity of the ACP.
Remote ind.
In contrary to the above remote operating mode, the remote individual mode allows the regulation of the
capacity of each compressor on the ACP individually from minimum to maximum level, with external signals.
These external capacity signals must be delivered by the customer as analog inputs to the electrical starter
panel IO-module (see also section 11.1). When a compressor is not running, then the remote signal must
exceed 2/3 of the minimum nominal capacity of that compressor, to start. A compressor will be stopped, when
the capacity request falls below 1/3 of that minimum nominal capacity.
Example for a slide valve regulated compressor with a minimum slide valve position of 50%: A capacity
request above 33.3% (2/3 * 50) must be given in order to start. Take in mind that the compressor will then
operate at the minimum capacity of 50% (after the start phase has expired), even if the request is lower. The
compressor will stop, when the requested capacity falls below 1
6.7% (1/3 * 50).
Example for a speed regulated compressor with a minimum speed of 25Hz and a maximum speed of 60Hz: A
capacity request above 27.8% (2/3 * 25/60 * 100) must be given in order to start. Take in mind that the
compressor will then operate at the minimum capacity of 41.7% (after the start phase has expired), even if the
request is lower. The compressor will stop, when the requested capacity falls below 13.9% (1/3 * 25/60 * 100)
Stopped
All compressors are stopped or stopped immediately when running.
Service
When this mode is selected, the dialogue expands allowing the user to input separate capacity for each
compressor. This is used for test and service purposes.
State
The Control screen also shows the status of three important signals [3]. These signals are all digital inputs to
the electrical panel IO-module.
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