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Configuration - continued
8. Set monitoring of compressor
Press the +-button to go on to the
next page
9. Set operation time for compres-
sor
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next page.
10. Set times for safety cutouts
Press the +-button to go on to the
next page .
11. Set Misc. functions
60
In our example we use:
- Common high-pressure pressure
control for all compressors
- One general safety monitoring
unit for each compressor
(The remaining options could have
been selected if specific safety
controls for each compressor had
been required).
Set min. OFF-time for the compres-
sor relay
Set min. ON-time for the compres-
sor relay
Set how often the compressor is
allowed to start
The settings only apply to the
relay that cuts the compressor
motor in and out.
They do not apply to unloaders.
If the restrictions overlap, the
controller will use the longest
restriction time.
In our example we do not use
these functions.
Capacity controller RS8GN202 © Danfoss 11-2013
If the limit is exceeded, the entire compressor capacity will
be cutout.
Pc Max delay
Time delay for the alarm Pc max
P0 Min limit
Minimum value for the suction pressure in °C
If the limit is reduced, the entire compressor capacity will be
cutout.
P0 Max alarm
Alarm limit for high suction pressure P0
P0 Max delay
Time delay before alarm for high suction pressure P0.
Safety restart time
Common time delay before restarting the compressor.
(Applicable to the functions: "Sd max. limit", Pc max. limit"
and "P0 min. limit).
SH Min alarm
Alarm limit for min. superheat in suction line.
SH Max alarm
Alarm limit for max. superheat in suction line.
SH alarm delay
Time delay before alarm for min./max. superheat in suction line.
Sd sensor pr. compressor
One shared Sd reading or one Sd sensor for each compressor.
8 - Compressor safety
Common safety
Choose whether an overall, common safety input for all
compressors is desired. If the alarm is activated, all compres-
sors will be cutout.
Oil pressure etc
Define here whether this type of protection should be connected.
For "General", there is a signal from each compressor.
9 - Minimum operation times
Configure the operation times here so "unnecessary opera-
tion" can be avoided.
Restart time is the time interval between two consecutive
starts.
10 - Safety timer
Cutout delay
The time delay resulting from drop-out of automated safety
measures and until the compressor-error is reported. This
setting is common for all safety inputs for the relevant
compressor.
Restart delay
Minimum time that a compressor should be OK after a safety
cut-out. After this interval it can start again.
11 - Misc. functions
Injection On
Select this function if a relay must be reserved for the func-
tion. (The function must be wired to controllers with expan-
sion valves in order to close liquid injection for the safety
cut-out of the last compressor.)
Network: The signal is sent to the controllers via data
communication.
Liq. inj suction line
Select the function if a liquid injection is required in the suc-
tion line in order to keep the discharge gas temperature down.
Regulation can be done either using a solenoid valve and a
TEV, or using an AKV valve.
Screw compresssor:
Special settings for screw compressors
Use Economizer
Select whether the controller should control an EVR for an
ECO function.
Use Liq. Injection (individual Sd)
Select whether there should be liquid injection to the com-
pressor in the event of high Sd. Must be stopped again 20 K
below "Max discharge".
Output type: Select the valve signal for the stepper or ana-
logue signa here.
Max liquid injection OD
Set the maximum degree of opening of the valve as a %.
Max discharge
Maximum Sd temperature in the event of any individual Sd
readings.
AK-PC 783
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