Disturbance recorder

Process data recorded just before a system breakdown have a significant meaning in modern industries. These informations help to resolve system failure cause and prevent error reoccurrence. 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 of this method is placing important information on a secure location: external nonvolatile memory card and remote station with Ethernet connection. The system is designed and tested for emergency stop sequence in hydro plant turbine governing system.