As part of London Underground’s ‘Cooling the Tube’ project, ventilation fans and associated dampers are placed at strategic points between stations to either extract the hot air from the tunnels or supply fresh (cooling) air to the tunnels. The aim was to provide a control system which would allow the ventilation fan to be run in either direction at either of two fixed speeds as per a pre-defined timetable.
Simonswood Automation designed and built control panels at the ventilation fan head house and at two stations either side of the ventilation shaft. The control panels were designed so that the fan could be run in ‘Local’ mode even with the PLC powered down. The PLC system used was the Mitsubishi Q Series, we utilised 3 PLCs, communicating with each over Ethernet. The PLCs were programmed with Mitsubishi GX IEC Developer. The SCADA system used was Wonderware InTouch, which was installed on a laptop which could be used at any of the three sites. The SCADA included a screen to enter a list of activation modes against the time to achieve the required timetable mode control. The control system was rigorously tested at our workshops with a test fan prior to being installed on site. Due to the nature of work, most of the commissioning activity had to be done at nights (during Engineering Hours).
The control system provides full automatic (timetable) of the ventilation fan and associated dampers. The system complies with the fire alarm requirements, switching to the required mode in response to alarms. The system also has the facility to log data to an external database, allowing the client to verify any operations at a given time.