The controller controls the defrost in the system based on either an electrical heater where the compressor is stopped, or at cycle inversion using warm gas where the compressor keeps on working. There are safety features which include shutting down the system incase of a fault from a pressure control or similar device. A series of “safety controls” (delay at start-up, minimum disable time, minimum time between activation) protects the compressors from close starts. In case of probe error or temperature alarm, the instrument signals the event through acoustic signal and by closing the relay contact. By pressing the mute key, the buzzer is silenced. 3 NTC probes for Room temerature, Coil temperature, Condensor Temperature. 1 RH sensor with 4 – 20mA input for humidification. Contactor outputs : Compressor, Condensor, evaperator, Relay output : Liquid SV,Alarm, light & humidifier. HP,LP, Compressor O/L, SPP, Pump O/L, Auxiliary Fault trip protection for Compressor and defrost. Auto/Manual reset for HP, LP and Compressor current sensing upto 20Amp. It also protect compressor by tripping it in underload & overload conditions.