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Safety PLC is ‘first’ with failsafe condition monitoring

20 November, 2018

ABB has developed what it claims is the world’s first safety PLC with integrated condition monitoring. It says the combination will enhance the functional safety of applications and reduce the need for manual inspections and maintenance.

For example, failsafe condition-monitoring opens up the ability to monitor the status of brakes on trains, AGVs or mobile machines safely, by measuring their vibration levels. Such monitoring could allow longer intervals between inspections, because it provides more precise data on the status of safety-critical parts.

Another potential application is the safe monitoring of vibrations in centrifuges and wind turbines. For instance, the system can supervise precise measurements of vibration signals with frequencies up to 20kHz, thus avoiding unexpected failures.

Failsafe condition-monitoring, together with predictive maintenance, provides an early warning that can help to prevent machine breakdowns and costly downtime. For example, the SLS (safely-limited speed) mode can be activated to reduce downtimes based on feedback from the failsafe condition-monitoring – instead of safe emergency stops – when permitted in an application.

The system is based on ABB’s AC500-S safety PLC, whose modular construction allows the PLC’s failsafe and condition-monitoring functions to be combined. Safety functions up to SIL CL 2 (IEC 62061), SIL2 (IEC 61511) and PL d (ISO 13849-1) can be implemented with failsafe condition-monitoring.

Analogue safety signal profiles can be saved in the PLC’s 120kB flash memory. The measured signals connected to the condition-monitoring module channels can then be compared with the saved profile. If the difference exceeds an allowed range, the safety reaction can be triggered.

ABB claims to be offering the first fail-safe condition-monitoring system integrated with a safety PLC.

ABB’s SM560-S-FD-4 safety CPU and CM589-PNIO-4 Profinet IO device are used to exchange the safe evaluation result from one failsafe condition-monitoring system with multiple safety controllers – including third-party ones ­– using Profinet/Profisafe. This allows full machine or plant-wide emergency-stop functions to be implemented, where required.

The PLC-based condition-monitoring can be integrated easily with all types of machinery, allowing precise management of the condition of applications in real time. This results in more efficient machines, predictable performance, and lower maintenance costs.

Whether used for standalone condition-monitoring or integrated into a machine or process control, the AC500-S PLC can be used to build optimised, self-analysing automation systems that simultaneously perform condition-monitoring, control, protection, safety and datalogging functions using a single controller.

Planned maintenance, rather than reactive repairs, ensures predictable performance. Potential damage can be identified early. The costs of maintenance and lost production time are reduced, and plant availability is increased. It is said to be easy to use, maintain, adapt or expand.

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