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High pressure control
If needed, offset for greater compressor capacity
Offset when there are requirements for heat recovery
Safety functions
Min. suction pressure
Max. suction pressure
Max. condensing pressure
Max. discharge gas temperature
Min. / Max. superheat
Safety monitoring of compressors
A bit more about the functions
Compressor
Regulation of up to 3 compressors on MT and 2 on LT
Up to 3 unloaders per compressor.
Compressor No. 1 or 2 can be speed-regulated.
P0 - Suction pressure is used as a regulation sensor.
When regulating with parallel compression (IT circuit),
2 compressors can be used to regulate MT, one on IT and along
with 2 on LT.
If regulating on MT only, 3 compressors can be used to regulate.
Gas cooler
Regulation of up to 4 fans.
Fans can be speed-regulated. Either all on one signal or only the
first fan of several. EC motor can be used.
Relay outputs and solid state outputs may be used, as desired.
An Sgc temperature sensor is used as a regulation sensor at the
gas cooler discharge.
Speed regulation of condenser fans
The function requires an analog output module.
A relay output may be used for start/stop of the speed regulation.
The fans may also be cut in and out by relay outputs.
Pulse wide modulating unloading
When using a compressor with PWM-unloading, the unloading
should be connected to one of the four solid state outputs in the
controller.
Heat recovery
There are adjustment options for hot water containers for domes-
tic hot water or for heating.
Connections
3
Here is a survey of the possible connections. The texts can be read in con-
text with the table on the following page.
Analog inputs
Temperature sensors
• Ss (suction gas temperature)
Must always be used in connection with compressor regulation.
• Sd (discharge gas temperature)
Must always be used in connection with compressor regulation.
• Sc3 (outdoor temperature)
To be used when regulation is performed with floating condenser refer-
ence.
• Saux (extra temperature sensor)
For monitoring, data collection or separate thermostat function.
• Shr (temperature sensors for heat recovery)
Must be used when adjusting the heat tank.
• Sgc (temperature sensor for gas cooling controls)
Shall be placed within one metre after the gas cooler.
• Shp (temperature sensor, the refrigerant may be bypassed gas cooler)
AK-PC 772A
x
x
x
x
x
x
x
x
Capacity controller RS8HF102 © Danfoss 2017-07
Common high pressure monitoring of compressors
Safety monitoring of condenser fans
General alarm functions with time delay
Miscellaneous
Inject On function
Option for connection of separate display
Separate thermostat function
Separate pressostat function
Separate voltage measurement
PI regulation
Max. input and output
Safety circuit
If signals are to be received from one or more parts of a safety
circuit, each signal must be connected to an ON/OFF input.
Day/night signal for raising the suction pressure
The clock function can be used, but an external ON/OFF signal
may be used instead.
If the "P0 optimization" function is used, no signal will be given
concerning the raising of the suction pressure. The P0 optimiza-
tion will see to this.
"Inject ON" override function
The function closes expansion valves on evaporator controls when
all compressors are prevented from starting.
The function can take place via the data communication, or it may
be wired via a relay output.
Separate thermostat and pressure control functions
A number of thermostats can be used according to your wishes.
The function requires a sensor signal and a relay output. In the
controller there are settings for cutin and cutout values. An associ-
ated alarm function may also be used.
Separate voltage measurement
A voltage measurement can be used according to your wishes.
The signal can for example be 0-10 V. The function requires a volt-
age signal and a relay output. In the controller there are settings
for cutin and cutout values. An associated alarm function may also
be used.
If you want to know more about the functions, go to
chapter 5.
Pressure transmitters
• P0 Suction Pressure
Must always be used
• Pc Condensing Pressure
Must always be used
• Pgc Gas cooler pressure.
Must always be used
• Prec. Pressure i CO 2 reciever
Must always be used
• Paux
One extra pressure transmitters can be connected for monitoring and
data collection.
x
x
10
x
4 +1
1
1
1
1
120
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