Safety PLC with fail-safe condition monitoring
26/02/2019
ABB has developed what it claims is the world’s first safety programmable logic controller (PLC) with integrated condition monitoring. It claims the combination will enhance the functional safety of applications and reduce the need for manual inspections and maintenance.For example, fail-safe condition monitoring opens up the ability to safely monitor the status of brakes on trains, automated guided vehicles (AGVs) or mobile machines, 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 of up to 20 kHz, thus avoiding unexpected failures.
Fail-safe condition monitoring, together with predictive maintenance, provides an early warning that can help to prevent machine breakdowns and costly downtime. For example, the safely-limited speed (SLS) mode can be activated to reduce downtime based on feedback from the fail-safe condition monitoring, instead of safe emergency stops, when permitted in an application.
The system is based on ABB’s AC500-S safety PLC, the modular construction of which allows the PLC’s fail-safe and condition monitoring functions to be combined. Safety functions up to
SIL CL 2 (IEC 62061), SIL2 (IEC 61511) and PLd (ISO 13849-1) can be implemented with fail-safe condition monitoring.
Analogue safety signal profiles can be saved in the PLC’s 120 KB 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’s SM560-S-FD-4 safety central processing unit (CPU) and CM589-PNIO-4 Profinet IO device are used to exchange the safe evaluation result from one fail-safe 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 stand-alone 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 data-logging 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.
Meanwhile, ABB has won an order to supply its ABB Ability™ Ellipse asset performance management (APM) solution to support Ameren Illinois’ multi-million-dollar modernisation of the energy delivery infrastructure across its service territory in Illinois, USA. The software solution will allow the energy company to better predict and prevent the failure of mission-critical equipment.
Electric utilities have traditionally carried out regularly scheduled ‘check-ups’ to maintain their grid infrastructure. While these check-ups can detect obvious or crisis-level issues, they may not predict conditions that could lead to possible failures down the line. The ABB Ability Ellipse APM solution, on the other hand, offers a prescriptive approach to maintenance. It uses sensors, data and advanced analytics to constantly assess the real-time condition of assets, determine when they might need repair or replacement and alert the stakeholders. This allows utilities to prioritise short- and long-term maintenance needs and drive productivity, safety and return on investment of critical grid assets.
Ameren Illinois has deployed ABB hardware, software and service in a relationship spanning more than three decades. Currently, the company deploys ABB power transformers, as well as ABB Ability software solutions such as ABB Ability Network Manager supervisory control and data acquisition (SCADA)/advanced distribution management system (ADMS), ABB Ability Velocity Suite, ABB Ability PROMOD® and ABB Ability distributed control systems.
A subsidiary of St Louis-based Ameren Corporation, Ameren Illinois is a regulated electric and gas delivery company. With a service territory comprising about three-quarters of the state, the company delivers electricity to 1.2 million customers. Its complex delivery system features 4500 miles of transmission lines and 46,000 miles of distribution lines.
