Introduction; Application - Danfoss AK-PC 772A User Manual

Application

AK-PC 772A is complete regulating units for capacity control of
compressors and gas cooler in a small CO 2 refrigeration systems.
Either as a compressor and condenser control on MT or as a boost-
er system. There can be regulated with one parallel compressor.
The controller is with oil management, heat recovery function and
CO 2 gas pressure control.
In addition to capacity control the controllers can give signals to
other controllers about the operating condition, e.g. forced clos-
ing of expansion valves, alarm signals and alarm messages.
The controller's main function is to control compressors and gas
cooler so that operation all the time takes place at the energy-
optimum pressure conditions. Both suction pressure and gas
pressure are controlled by signals from pressure transmitters and
temperature sensors.
Among the different functions are:
- Capacity control of up to 3 compressors on high pressure
(2 if also regulating with parallel compressor).
- Capacity control of up to 2 compressors on low pressure
- Up to 3 unloaders for each compressor
- Speed control of one or two compressors
- Up to 6 safety inputs for each compressor
- Option for capacity limitation to minimize consumption peaks
- When the compressor does not start, signals can be transmitted
to other controllers so that the electronic expansion valves will
be closed
- Control of liquid injection into suction line
- Safety monitoring of high pressure / low pressure / discharge
temperature
- Capacity control of up to 4 fans
- Floating gas cooler reference with regard to outside temperature
- Heat recovery function
- CO 2 gas cooler control and receiver control
- Parallel compression on transcritical CO 2 system
- Step coupling, speed regulation or a combination
- Safety monitoring of fans
- The status of the outputs and inputs is shown by means of light-
emitting diodes on the front panel
- Alarm signals can be generated via data communication
- Alarms are shown with texts so that the cause of the alarm is
easy to see.
- Plus some completely separate functions that are totally inde-
pendent of the regulation – such as alarm, thermostat, pressure
and PI-regulating functions.
SW=1.3x
AK-PC 772A

1. Introduction

Capacity controller RS8HF102 © Danfoss 2017-07 3