Danfoss AK-PC 772A User Manual page 34

Voltage signal
• Ext. Ref
Used if a reference override signal is received from another control.
• Voltage input
One extra voltage signal can be connected for monitoring and data
collection
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
• Signal from the condenser fans 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.
• Level contacts
Example
Compressor group:
MT circuit
• 3 x compressors with "Cyclical". One speed-controlled
• Safety monitoring of each compressor
• Common high pressure monitoring
• P0 setting –10°C, P0 optimisation
LT circuit
• 2 x compressors with "Cyclical". One speed-controlled
• Safety monitoring of each compressor
• Common high pressure monitoring
• P0 setting –30°C, P0 optimisation
Gas cooling control:
• Fans, speed controlled
• Pressure regulation Pgc with reference from Sc3 and Sgc
• Pressure increase for heat recovery
34
Containers:
• Control of pressure in CO2 receiver
• Controlling the tank temperature for domestic water, 55°C
Safety functions:
• Monitoring of Po, Pc, Sd and superheat in suction line
• MT-Po max = -5°C, Po min = -35°C
• MT-Pc max = 110 bar
• MT-Sd max = 120°C
• LT-Po max = -5°C, Po min = -45°C
• LT-Pc max = 40 bar
• LT-Sd max = 120°C
• SH min = 5°C, SH max = 35°C
Capacity controller RS8HF102 © Danfoss 2017-07
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 suction line
• Start/stop of valve and circulation pump for heat recovery
• ON/OFF signal for start/stop of speed regulation
• Alarm relay. I'm alive relay.
• On/off signals from general thermostat (1), pressure switch (1) or voltage
input function (1).
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).
• Should be used if controlled using a digital scroll compressor.
Analog output
• Speed regulation of the condenser's fans.
• Speed regulation of the compressor
• Stepper signal for high pressure valve
• Stepper signal for hot gas by-pass valve
Data from this example is used on the
next page.
The result is that the following modules
should be used:
• AK-PC 772A controller
• AK-XM 208C stepper output module
• AK-XM 103A analog input and output
module
AK-PC 772A