Available with a capacity range of 100-450 tons of refrigeration (TR), the ammonia compressor packs (ACP) are a range of compressor units designed for use with refrigerant R-717. The modular compressor units comprise up to three compressors. As many as three compressor packs can be connected together and operated by a single controller, increasing the capacity up to 1,200 TR. The primary compressor is equipped with a frequency inverter and ensures optimal part-load performance. The frequency-regulated primary compressor features an insignificant starting current peak. The second and third compressors feature automatic start unloading. Individual compressors can be turned on and off depending on requirements. The controller and the most important sensors are redundant to increase system reliability. According to the manufacturer, the ACPs are designed for use in areas subject to stringent requirements in terms of operating reliability.