Engineers at Qilu, one of the largest polyethylene production sites in China, have upgraded their plant's safety system by installing an ICS Triplex 'Trusted' system
Engineers at Qilu, one of the largest polyethylene production sites in China, have upgraded their plant's safety system by installing an ICS Triplex 'Trusted' system, the only control system that could meet the demanding specification. The operators had calculated that to ensure safety the system had to be scanning every point in the plant at least every 100ms. Qilu had 800 input/outputs (i/o) to be monitored, including over 300 analogue inputs, each of which would take a conventional safety system a relatively long time to interrogate.

It soon became apparent that Trusted was the only system that could achieve the scan time compulsory requirement.

'We developed a new Central Processor Unit (CPU) for Trusted just two years ago, which has made it very much more powerful than equivalent systems,' says Antonio Invernizzi, of ICS Triplex's Milan office, which supplied the hardware for the project.

'Normally we use it with 40 channel i/o modules, but even with the 16 channel units that were specified for this project we were able to exceed the scanning specification.' Trusted is a Triple Modular Redundancy (TMR) safety system, which is inherently fault tolerant.

It recognises faults and isolates them while maintaining the system's safety performance at 100 per cent.

Overall availability is therefore higher than with other systems, so that neither productivity nor safety are ever compromised.

Trusted has been certified by TÜV to DIN V VDE 0801 RC(AK)6, confirming its suitability for use in emergency shut-down, fire and gas and other critical control applications.

A key benefit of the of the Trusted TMR concept is its exceptional availability which translates to more plant up time and greater production combined with the highest levels of safety.

This is achieved by the fault tolerance of the TMR architecture that identifies and outvotes processor mismatches to keep running safely in the presence of a fault, almost entirely eliminating spurious plant trips.

Trusted employs a hardware implemented, fault tolerant (HIFT) voting system that cuts software complexity.

The main contractor for the project was Technip Italia and the systems integrator was a company called Program.

Both are based in Rome, and ICS delivered the £150,000 worth of hardware to them there.

ICS also provided IEC 1131 Toolset, the company's software for programming and maintenance.

This is installed in the system on a supervisory PC that also runs a graphics front end package called Panorama which presents real time and historic process data in an easy to understand way.

Invernizzi sums up: 'The Qilu plant has been up and running for just over a year, and the operators have noted the performance of the Trusted system.

there has been a step improvement of the safety record of the plant, with virtually no false alarms to disrupt normal running of the plant.'