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Product category: Electrical and Electronic Components
News Release from: Marl International | Subject: Lumarled
Edited by the Engineeringtalk Editorial Team on 12 February 2003

LEDs last longer under ground

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Infraco JNP has successfully replaced the tungsten filament lamps previously used in its tunnel signals with long life retrofit Marl units based on LED technology.

Infraco JNP (one of the three infrastructure companies providing assets to London Underground) has successfully replaced the tungsten filament lamps previously used in its tunnel signals with long life retrofit Marl units based on LED technology These units are being progressively installed throughout the Jubilee, Northern and Piccadilly lines

JNP is in the process of evaluating use of LED technology in other asset areas including tunnel lighting, surface signals, and station repeaters.

The mean time between failures for a tungsten filament lamp in the harsh underground environment is around 24 weeks.

The LED unit (Lumarled), which was developed jointly by London Underground and Marl, has an MTBF of over eleven years.

"In addition to the extended life, one of the real benefits is that it's retrofit.

Some of these assets last for 30 to 40 years, so you don't want to replace or undertake redesign work in order to introduce LED Technology", said Mark Scotter, JNP's Technology Strategy Manager.

The power consumption is also less at around 10% of the power of a tungsten filament lamp.

A further benefit of using the technology is that it improves safety.

"The railway is a very hazardous environment and if you can put something in that lasts a guaranteed five years compared to 24 weeks then you're reducing the need for individuals to be down on the track", added Scotter.

The Lumarled comprises a small cluster of high performance LED elements, combined with sophisticated electronic drive and protection circuitry.

This is enclosed in a specially designed, rugged, thermoplastic housing with integral lens.

The unit is terminated with a bayonet lamp cap to allow simple, yet effective replacement of both the main and standby bulbs in the host signal head enclosure.

The optical performance of the product is designed to replicate the output of the existing incandescent bulb when the train driver views the signal.

JNP has recently signed a contract with Marl for it to investigate the application of LED technology in other signal and lighting asset areas.

One application that looks particularly promising is tunnel lighting lamps.

These currently use fluorescent tubes whereas an LED unit would last considerably longer.

"You're talking about a high volume of lamps situated throughout the tunnels.

If we can increase the time between replacement, it's going to benefit London Underground (our customer) and ourselves (JNP)", said Scotter.

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