Danfoss ADAP-KOOL AK-PC 781 Design Manual page 36

• Sgc (temperature sensor for gas cooling controls)
Shall be placed within one metre after the gas cooler.
• Shp (temperature sensor, if the refrigerant can be routed outside of the
gas cooler)
Pressure transmitters
• P0 Suction Pressure
Must always be used in connection with compressor regulation
(frost protection).
• Pctrl (control pressure for cascade)
Must only be used if the control sensor for compressor control has been
selected as Pctrl (cascade)
• Pc Condensing Pressure
Must always be used in connection with compressor or condenser
regulation
• Prec. Oil receiver pressure. Must be used for receiver pressure regulation.
• Pgc Gas cooler pressure. Must be used for CO2 transcritical operation.
• Prec.CO2 Pressure reading in the CO2 receiver. Must be used for CO2
transcritical operation.
• Paux (1-5)
Up to 5 extra pressure transmitters can be connected for monitoring and
data collection.
These sensors can be used for general pressure switch functions.
Note. A pressure transmitter type AKS 32 or AKS 32R can supply signals to
a maximum of five controllers.
Voltage signal
• Ext. Ref
Used if a reference override signal is received from another control.
• Voltage inputs (1-5)
Up to 5 extra voltage signals can be connected for monitoring and data
collection. These signals are used for general voltage input functions.
On/Off-inputs
Contact function (on an analog input) or
voltage signal (on an extension module)
• Common safety input for all compressors (e.g. common high-pressure/
low-pressure pressure switch)
• Up to 6 signals from the safety circuit of each compressor
• Compressor release signal on LT controller in cascade
• Compressor requirements signal on MT controller in cascade
Example
Compressor group:
• MT circuits
• Refrigerant CO2 (R744)
• 4 only compressors with "Best fit". One speed controlled
• Safety monitoring of each compressor
• Common high-pressure monitoring
• Po setting -15°C, night displacement 5 K
• Oil management of each compressor
• Pulse reset for stopped compressor (lack of oil)
High pressure controls:
• Heat recovery for tap water
• Heat recovery for heating circuit
• Gas cooler
• Fans, speed controlled
• Pc regulates based on temperature sensor Sc3 and Sgc
Receivers:
• Monitoring of CO2 level
• Control of pressure in oil receiver
• Controlling the tap water receiver temperature, 55°C
• Controlling the receiver temperature for the heating
circuit, 40°C
36
Fan in plant room
• Thermostat control of fan in engine room
Safety functions:
• Monitoring of Po, Pc, Sd and superheat in suction line
• Po max = -5°C, Po min = -35°C
• Pc max = 50 °C
• Sd max = 120°C
• SH min = 5 °C, SH max = 35 °C
• Monitoring of low and high level in oil receiver
Other:
• Alarm output used
• External compressor stop used
Capacity controller RS8GG602 © Danfoss 2015-03
• Signal from the condenser fans safety circuit
• Any signal from the frequency converter's safety circuit
• External start/stop of regulation
• External day/night signal (raise/lower the suction pressure reference). The
function is not used if the "P0 optimization" function is used.
• DI alarm (1-10) inputs
Up to 10 no. extra on/off signals for general alarm for monitoring and
data collection can be connected.
• Flow switch for heat recovery
• Level contacts
On/off-outputs
Relay outputs
• Compressors
• Unloaders
• Fan motor
• Injection On function (signal for evaporator controls. One per suction
group).
• Start/stop of liquid injection in heat exchanger
• Compressor release, output signal from MT controller in cascade
• Compressor request, output signal from LT controller in cascade
• Start/stop of liquid injection in suction line
• Start/stop of 3-way valves at heat recovery
• ON/OFF signal for start/stop of speed regulation
• Alarm relay. I'm alive relay.
• On/off signals from general thermostats (1-5), pressure switches (1-5) or
voltage input functions (1-5).
• Oil valves
• Safety relays for cutouts of compressors at oil failure
Solid state outputs
The solid state outputs on the controller module may be used for the
same functions as those mentioned under "relay outputs". (The output will
always be "OFF" when the controller has a power failure).
Analog output
• Speed regulation of the condenser's fans.
• Speed regulation of the compressor
• Speed control of pumps for heat recovery
• Control signal for high pressure CO2 valve. (stepper signal.
• Stepper signal for hot gas by-pass valve
)
if applicable
Data from this example is used on the
next page.
The result is that the following modules
should be used:
• AK-PC 781 controller
• AK-XM 205A input and output module
• AK-XM 208C stepper output module
• AK-XM 102B digital input module
• AK-XM 103B analog input and output
module
• AK-OB 110 analog output module
AK-PC 781