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CT-600-2
PID TD
Parameter to tune the damping time of the derivative action.
PID setpoint ramp limit
Parameter to define the ramp time of the setpoint (minutes per unit of pressure
or temperature). See figure below for explanation of ramp function.
PID deadband
Parameter that defines the deadband of the PID regulator. If the process value
is within a distance of plus or minus the deadband value from the setpoint, then
the regulator output will not change.
PID output high/low limit
Parameters to make sure the output high limit is set to 100 and the output low
limit is set to -100, unless the output should be limited. The PID regulator will
itself limit the output, depending on the amount of capacity available, since this
can vary depending the amount and type of compressors that are ready for
operation.
PID inner/outer window I-part
Parameters to limit the integration action of the PID regulator. If the absolute
value of the process error is above the outer window, then the integral part of
the output will hold the last value (anti reset windup). If the absolute value of
the process error is below the inner window part, the integral part of the output
will be scaled with that same value. Else the integral calculation will be normal.
Eco superheat low and high warning and alarm limit (Economizer \ Page 1)
Parameters to adjust the limits for surveillance of the economizer gas superheat.
Timer setting (Param. \ Timer)
The screen to view and edit the timers is part of the parameter pages. Most timers can normally be left to
default values. See also the function description in section 11 with more information on the use of the timers.
The timers that are mentioned specifically below here, are some that may need to be adjusted, depending on
the configuration of the system.
Oil sep. level low warning time (Timer Page 1)
Timer to set the time that the oil level in the separator must be low, before an alarm will be issued that stops
the compressors. The warning is intended to indicate the user to top up oil or to find out why oil is missing.
Capacity limiter step time (Timer Page 2)
Timer to set the time that the capacity limiter will wait after reducing the capacity with the amount given by the
parameter “Module capacity limiter step” (see also section 9.3) until the next reduction step will be taken.
Both the parameter and timer can be used to tune how aggressive the capacity limiter function should react.
0
10
20
30
40
50
60
70
0
1
2
3
4
5
6
7
8
9
0
5
10
15
20
25
30
35
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45
50
PI
D
out
put
[%
]
PV
,
SP
[b
ar
a]
Time
[min]
PV
SP
user
SP
Regulator
Ramp
status
PID
output
Ramp
status
(PV: process
value,
SP:
setpoint)
