Disturbance recorder

Very important information in modern industries is process data recorded just before system breakdown. These are being used for resolving system failure cause and error reoccurrence prevention. A safety backup implementation into PLC system is limited due to low memory and similar performance issues. The paper presents a method for compressing and recording process data using a PLC and an operator panel. The main advantage is placing important information on secure location: external memory card and remote station with Ethernet connection. The system is designed and tested for safety stop sequence in hydro plant turbine governance.