GE Intelligent Platforms has announced a redundant control system with four separate controllers that, it claims, will almost eliminate the risk of downtime.

The Quad PAC controller (shown below) consists of two redundant pairs of GE’s PACSystems RX7i controllers – and associated items such as racks and power supplies – working as a master controller and three synchronised backup controllers. The controllers are connected via redundant high-speed fibre optic modules, which provide synchronised logic-solving and data transfer between them. Similar technology is used via network hubs to tie the four controllers into a cohesive quad-redundant system.

If the master controller or any other components fail, the system identifies the best backup controller to take over and withstand the next sequence of system failures. A patent-pending algorithm calculates the relative system availability continuously in real time and delivers predictive analysis of key process input variables to identify the next master controller most capable of surviving a system failure while maintaining maximum system availability.

The controller uses GE’s PACSystems RX3i Remote I/O system and redundant Ethernet LANs that can change I/O control seamlessly to one of the four controllers. Each remote I/O rack supports redundant network interfaces and provides all four controllers with the system inputs and outputs in an arbitrated format. The remote racks can be grouped into a single, double or triple redundant configurations, in which each rack communicates independently with all four controllers, and each controller shares the same input and output point addresses from each I/O rack.

“Continuity of operations is critical, and a quad-redundancy control system ensures that any process can continue without interruption by having one of its three backup counterparts assume control if failure occurs,” explains Mark Reitzel, commercialisation leader of GE Intelligent Platforms Applied Solutions. “In addition, this type of high-availability system can also help reduce costs by enabling maintenance or exchange of individual system components without system interruption and no loss of system redundancy or availability.”