Mitsubishi Electric launches redundant safety controller

Mitsubishi has added a dual redundant safety controller to its high performance MELSEC iQ-R Series process CPU range. In the event failure of the main CPU, power supply or base unit, the secondary system starts immediately (under 21 ms) from the same control point.

The system uses dual optical-fibre tracking cables enabling the standby system to be up to 550m from the control/primary system. Online replacement of modules (hot-swapping) is possible without stopping the operating control system.

For users this has two major benefits. Firstly, no operational damage due to a single system failure and production that continues seamlessly. Secondly, quick recovery and extra reliability, reducing waste and downtime. This allows critical systems to operate in case of a failure or damage to the primary CPU unit.  The system also integrates various features into the PLC for monitoring and managing safety.

Redundant safety controller

Many key production applications need full redundancy conforming to the IEC 61508 SIL 2 standard. For this reason, the iQ-R includes another layer of protection, added to its redundancy architecture. The MELSEC iQ-R redundant pair of PLCs follow the functionality rule of this standard, with certification by TÜV Rheinland. It calls for a full duplicate PLC rack with all modules, which the primary set will switch-over to instantaneously.

The safety version includes a SIL2-process CPU module and a separate SIL2-function module as a set. This sits alongside the power supply module, basic base unit and network module. This ensures continuous operation by switching to standby operation if an error occurs in the control system.

MELSEC iQ-R Series process control capabilities

Process integrity and dependability are the main reasons for installing redundant automation controllers. MELSEC iQ-R process redundant systems are ideal for various industrial process control applications. In particularly, those requiring highly reliable process control solutions. Most components are from the standard range of MELSEC iQ-R Series modules. This therefore helps to reduce total cost of ownership to through use of its extensive functions and features.

In oil and gas applications, redundant controllers manage break systems for crane equipment, ESD systems and pipelines. It is also ideal for industries requiring precise ingredient mixing and recipe management. This includes chemical or food and beverage where disruption in one stage may lead to bottlenecks in others. Likewise, building automation uses them to manage HVAC, lighting, lifts, and emergency responses. DCS style features in a cost-efficient automation control system.

The iQ-R’s high performance process control system incorporates a dedicated process instruction set. Such as two-degree-of-freedom PID, sample PI, and auto-tuning, realising algorithmic PID. and highly reliable. features such as being able to interchange (hot-swap) I/O modules while the system is still online. Finally, it handles process control of 500 loops gives it DCS capabilities without the financial burden.

MELSEC iQ-R uses Mitsubishi’s common programming platform GX Works3 engineering software. Overall, it enables the execution of integrated process and safety control programs with a single CPU module. This eliminates the time and cost of purchasing and installing a separate safety controller.