Fire and gas detection systems are vital to give advanced warning of life safety and facility protection threats in hazardous areas. Oil rigs in the North Sea are located in some of the most inhospitable environmental conditions to be found, adding to the issues faced by operators in ensuring 24/7/365 operation. Verotec has recently supplied a large number of custom 19” fan trays to Traycar Systems, who will be retrofitting them to legacy Ferranti control cabinets that date back to 1983 when the rig was first commissioned. The upgrade is intended to provide many more years of safe and reliable operation with the minimum of disruption during the installation.
The Verotec custom fan trays are 1U 19” 400mm deep units fitted with two independent banks of three 110VAC fans and three 24VDC ones, each with dedicated local indicators. In normal operation, both the 110VAC and 24VDC fans are powered, giving 100% cooling capacity. If either power supply is lost, then 50% cooling is maintained, and if both power supplies fail then the alarm is generated by two independent relays, one for each voltage rail. Given the safety-critical nature of the fire and gas detection systems, it is imperative that control and monitoring is not compromised by overheating in the event of multiple power losses. EMC considerations in such an electrically noisy environment required the entire chassis to be electrically conductive; the ventilation pattern in the top cover was computer designed to provide maximum open area with minimal degradation to the EMC integrity of the units.