3 March 2015

Raytheon UK delivering SiC components for use in current-limiting diode project

Raytheon UK's semiconductor business unit in Glenrothes, Scotland, UK is partnering on a project that would provide aircraft electronics and wiring with a more efficient device to protect against lightning strikes, which can damage sensitive equipment.

During electrical storms, lightning paths travel cloud-to-ground or cloud-to-cloud, and sometimes aircraft in flight can form part of the path. The outer skin of the aircraft (which is traditionally aluminium) does much to accommodate the lightning's path, and voltage 'surge suppression' devices are used to protect aircraft electronics.

"However, with composite materials replacing metallic components and skin materials, the reduced electrical screening in airframes is forcing a rethink of lightning protection architectures," says John Kennedy, head of Raytheon UK's Integrated Power Solutions. "Current-limiting diodes (CLDs) will essentially absorb much of the electrical energy that the dampening device would otherwise have to channel during a lightning strike," he adds.

The project - led by Rolls-Royce Controls and Data Services Ltd and involving the UK's Newcastle University in the role of design authority as well as Semelab Ltd of Lutterworth, UK (a subsidiary of TT Electronics plc) - is exploring the use of Raytheon's and Newcastle University's high-temperature silicon carbide (SiC) technology to make CLDs; a new kind of lightning protection device that stands to reduce the amount of electrical energy traditional suppressors have to deal with during a lightning strike.

"In striving for lighter and more fuel-efficient aircraft, it is important not to compromise the lightning protection function," says Kennedy. "CLDs have the potential to absorb excess energy surges induced in the electrical wiring by a lightning strike, while reducing the size and therefore the weight of the traditional suppressor devices," he adds. "CLDs solve a specific problem of dealing with electrical surges by dissipating induced lightning energy more efficiently, while also contributing to the industry's weight-saving goals."

Currently in phase one, Newcastle University is conducting electrical characterization tests while TT Electronics Semelab develops the CLD packaging. The two-phase project, funded under Innovate UK, is expected to be completed by late 2015.

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Scotland's Raytheon Glenrothes opens SiC foundry

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