Today convencional signals with light bulbs are replaced by LED lights to reduce energy consumption and maintenance costs. Institute Mihajlo Pupin developed LED light source (LL-70-m, LL-100-m, LL-136-m, LL-160-m, LL-200-m, LL-210-m, LL-136-m KS) intended for use in railway colour light signals as a replacement for two-filament light bulbs in legacy, relay-based interlocking systems, as well as a light source for signals in modern, electronic-based interlocking systems. It is comprised of seven individually controlled and monitored LEDs  and can operate in three different modes: day-time, night time and blinking operation.

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Due to the complex operating requirements of a relay interlocking, LL-000 implements a modular and flexible design capable of supporting wide range of operating conditions, applicable on different types of interlocking systems.

When used on the SpDrS-64, LL-000 doesn’t require any modifications on the interlocking system, other than replacing light bulb housing with LL-000 or replacing just light bulb with LED module. This use case has been successfully proven on Serbian railways where more then 200 pcs. of LL-000 signals were installed on Raiway corridor section Pancevacki Most – Pancevo main station (Republic of Serbia).

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Main advantage of LED signal over incandescent light bulb signal (for SpDrS-64 or any other relay based interlocking systems) is considerably longer life time and availability, which greatly reduces maintenance cost.

A version of LL-000-EI was also developed to satisfy different electronic interlocking requirements. More than 250 pcs. of LL-000-EI signals were installed in Pancevo main station (both LL 136 EI and LL-70-EI) for purposes of integration with electronic interlocking SML 400.

This use case proves the advantage of the modular design, as it reduces cost of adapting LL-000 to different kind of interlockings.

Light source of LL-000 consists of seven individually controlled and monitored high current LEDs. Each LED has its own small, narrow beam lens, which greatly simplifies inner mechanics of LL-000 and proves that bulk glass lens and light bulbs are not necessary.

Due to the fact that LL-000 uses colour LEDs, colour filters are also not necessary. This also means that colour phantom signals are not possible.

 More information about Railway LED signal >>> Railway LED signal 2019- EN