The AK-PC 772B units are designed for efficient capacity control of compressors and gas coolers in small CO2 refrigeration systems. These units can function either as a compressor and condenser control on Medium Temperature (MT) systems or as a booster system. They also support regulation with one parallel compressor. The controller includes oil management, heat recovery function, and CO2 gas pressure control.The controller’s main function is to control compressors and gas coolers so that operation always takes place at the energy-optimum pressure conditions. Both suction pressure and gas pressure are controlled by signals from pressure transmitters and temperature sensors.