Next Generation of LED Leads

Aerospace – Airports are pleased to announce that further developments in LED technology now enable the ICAO CAT III taxiway centreline offset and curved applications to be achieved.

A breed of more powerful 3W LED arrays can now be installed in the ZA280 inset taxiway fixture. By increasing the LED power from 3W to 9W per direction can provide the additional lighting required for these more demanding specifications.

The ZA280 will now be offered with either 1W LED arrays for straight sections or 3W LED arrays for the offset and straight applications.

Managing these more powerful LEDs has provided additional challenges to the thermal aspects of the design. The LED arrays are mounted on a insulated metal substrate with superior thermal qualities that ensure that the maximum operating temperature of the LEDs is not exceeded, even in hot climates.

Recent testing for FAA-type approval showed that these LED devices could withstand prolonged operation at temperatures of 55°C with minimal degradation of the light performance. At temperatures below freezing, additional resistor heaters can be added as an option to remove ice and snow from the optical surfaces, thus ensuring the safe operation of ALSTOM LED products over a range of temperatures.

In existing AGL installations, the new 3W LED-based ZA280 LED fixture may be operated from the ALSTOM power convertor the ZL836, which matches the dimming performance of the LEDs with the existing tungsten halogen current response. The ZL836 is an interface constant current device that is installed between a conventional airfield ground light transformer and the LED airfield light by a secondary lead of up to a length of 100m.

The ZL836 also features a field switch options that can be enabled or inhibited by a separate 48VDC supply and thus can be used as an interlocking control circuit for the stop bar and taxiway centre line lead on lights.

As LED technology gains further acceptance in to airfield ground-lighting equipment it is expected that eventually that AGL LED-based fixtures will be operated directly from isolating transformers and field switches without the need for any interfacing electronics – the intermediate brilliancy levels being created from different current levels. ALSTOM already has a range of transformers that can meet this role in preparation for such new LED-based lighting schemes.

The introduction of higher power LEDs into the curved and offset taxiway centreline applications is an exciting development for the airfield ground-lighting industry as it signals the potential step to the introduction of LEDs to runway applications, such as the elevated threshold or elevated end, and eventually the complete runway.

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