AK-PC 840 is a controller for capacity regulation of compressors and condensers for medium and large refrigeration systems. It controls up to 12 compressors and up to 3 unloaders for each compressor. AK-PC840 features variable speed regulation of one of the compressors (e.g. lead compressor via AKD speed drive). AK-PC840 controls up to 12 condenser stages and/or can offer variable speed control of fans via AKD drive. Temperature sensor = type AKS (Pt1000) Pressure transmitter = type AKS 32R + cable conn. Display = EKA 162 (or PC via Service Tool) Indication Display: LED’s on the controller. Extension modules for additional inputs/outputs: AK-XM 101 = 8 Analogue Input module. AK-XM 102 = 8 Digital Input module. AK-XM 205 = 8 AI / 8 DO module.