Firstco, one of the UK’s leading technical consultancy, project management and systems integration specialists, has just completed the customer factory acceptance testing of a ControLogix PLC system that is believed to be one of the largest of its kind in Europe. The PLC network architecture was specified by Firstco’s design team working, in partnership with BAA, on the prestigious Terminal 5 (T5) Project at London’s Heathrow Airport.

Five levels below the terminal building is a six platform railway station that will handle the Heathrow Express and Piccadilly Line services, as well as providing potential future connection to the South West lines.

The PLC network controls and monitors all of the T5 rail station systems. These include train information displays, tunnel ventilation, public address, CCTV, fire and utilities.

The PLC network runs through the 2.5km long Heathrow Express tunnel linking the T5 site to the existing PLC network at the Heathrow Central rail station. The entire network will now cover a geographical area of some 25km as the existing network is linked to both Terminal 4 and Paddington station.

Due to the critical nature of the tunnel ventilation system, the PLC network was specified as having to meet the requirements of BS EN61508 Safety Integrity Level 2. The design was, therefore, based around Rockwell Automation’s Allen-Bradley’s ControLogix SIL2 rated range of equipment.

The new PLC network uses over 10km of redundant cabling, both copper and fibre, to connect 23 PLCs on a ControlNet network. Eighteen of the PLCs are configured as hot standby fully redundant pairs and are SIL2 compliant.

The PLCs are networked to 49 purpose built remote I/O control panels, giving connection to approximately 2,400 digital and analogue I/O points. In addition to the hardwired inputs, the system also has seven separate protocol interfaces allowing the control room staff seamless control of the various third party systems.

A redundant server/client RSView SCADA System brings all of the systems together to provide a fully integrated user interface.

An additional single headed workstation will be added to the five existing triple headed and two single headed workstations currently in use. The additional control and monitoring required for the new T5 systems has been engineered into the existing graphical user interfaces (GUIs) to ensure that the entire network, now comprising of 53 PLCs, appears and operates as one single, integrated system to the operators.

Firstco’s managing director, Bill Martin, said: “Ultimately the success or otherwise of a project such as this is how easy the end users find the system to operate. By working closely with Heathrow Express we have been able to deliver a SCADA system that provides the control room operators with a fully integrated user interface that belies the complexity of the systems at field level.

“Working on a project of this size with some of Rockwell Automation’s latest products and technologies has put us at the forefront of this type of PLC architecture.”