Multifunctional capacity controller

The AK-PC 781 capacity controller by Danfoss constantly optimizes compressors and condensers and offers oil management, heat reclaim and CO2 control.


The AK-PC 781 capacity controller by Danfoss constantly optimizes compressors and condensers and offers oil management, heat reclaim and CO2 control. Courtesy: DanfossThe AK-PC 781 Multifunctional Pack Control from Danfoss makes it easy to set up energy-efficient capacity control of refrigeration compressors and condensers with modular hardware and flexible software that extends as system requirements grow or change.

The AK-PC 781 capacity controller ensures precise and stable suction and condensing pressure regulation for a variety of applications and refrigerants. Modules snap onto a common platform to accommodate digital and analog inputs and outputs for compressors, condensers, gas coolers, fans, expansion valves, sensors, switches and alarms. Capacity control is available for up to eight compressors, with three unloaders for each compressor. Functions include speed control of one or two compressors, handling up to six safety inputs per compressor, optional capacity limitation to minimize peak energy consumption, capacity control for up to eight fans and coordinating cascade controllers for medium- and low-temperature operation.

Advanced module features support heat recovery for hot tap water production and general heat recovery in transcritical CO2 booster systems.

Controller programming is easily accomplished with a PC using AK-Service Tool software. The controller networks with other Danfoss ADAP-Kool refrigeration control systems. External data communications is supported by a Modbus extension module.

Each module is 2.8 inches long, with the controller itself consisting of three modules. Aggregate unit length is calculated as number of modules multiplied by module length, plus 0.32 in. Minimum weight is 0.9 lb. The unit is designed for a DIN-rail mount.


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