S4GA - Helipad and Airport Lighting Company
ajax loader

NEWS

Jan 16 2017
Is Hybrid AGL More Reliable Than Conventional Lighting?

Is Hybrid Airfield Lighting more reliable than Conventional (Wired)?

Conventional Airfield Ground Lighting (AGL) systems today are well known to Engineering Companies and Airport Planners. For almost 100 year conventional (wired) lighting has been the only choice for the airports. However thanks to rapidly evolving technology airports today can choose between conventional and hybrid AGL. Question that is worth to ask “Is hybrid AGL more reliable than conventional (wired)?”.

To understand the difference between two systems please refer to the graphics below. Even though both system are used to illuminate the same runway – the philosophy of design is very different. Hybrid AGL design uses significantly less elements yet providing higher redundancy. Why? Because of superiority in Power, Reliability and Control.

History of H-AGL

S4GA Hybrid Airfield Ground Lighting (H-AGL) is used today as primary, emergency and temporary system by both airports and helipads all over the World.

Battery-powered system has been designed at first to be used as an emergency lighting. However with development of solar energy, power saving LED-based lights and deep-cycle batteries those systems are now used as primary runway lighting by many airports.

One of S4GA’s shareholders is an airline pilot therefore we all aware of “where system is used” and especially “of its impact on safety of passengers”.

We in S4GA use old-pilot way of thinking – be prepared for the “worst case scenario”. This is how S4GA systems has been designed. Here is our philosophy in regards to: Power, Reliability and Control

Power in H-AGL

Every lighting unit is autonomous due to in-built deep-cycle battery, which allows for up to 50 hours of continuous operations. H-AGL is designed to operate only when needed. Example: airplane landing (from the moment when pilot has runway in sight) takes max. 20-25 minutes. It means that in 6 hours airport can process up to 15 landings which is usually more than enough to handle night air-traffic for regional or domestic airport. 6 hours means that battery only uses 12% of its capacity.

Solar panel is used NOT to power the unit BUT to charge the battery so there is no risk of system being inoperative during the night time. Let’s refer to the example provided above: as each unit is equipped with MPPT technology maximizing solar charging – 20 minutes of charging by day is required per one hour of unit’s operations by night. It means that unit requires only 2 hours to re-charge itself after rather busy night.

Assuming “worst case scenario” we can’t always rely on sunshine availability. Therefore S4GA system offers two additional ways to charge the lighting unit (apart from solar-based charging). (#1) separate charging station that can charge up to 10 lighting units simultaneously. Charging time is 6-7 hours therefore discharged units can be charged by day. (#2) via cable ( lighting unit can be connected to electrical grid that provides 24V, 1.5A DC power. in this case in-built battery provides back-up power. in case of electrical failure unit will be powered by the battery).

To sum-up: In case of H-AGL lights are 100% autonomous, powered by batteries. Battery provides with more reliability than generator. Because when generator is off – electrical circuit is de-energized. But when sun is off – battery still has capacity to support night operations for over a week (assuming NO sun at all). If there is no sun or sun is limited and batteries have not enough capacity – airport personnel is informed with automatic alarm SMS-based system. In this case airport personnel has to de-mount units and re-charge them using stationary chargers.

If airport requires the highest possible redundancy level: it is possible to add simple cable infrastructure and simultaneously connect each unit to cable and solar-panel. In this case: units are using solar energy to charge batteries. When there is not enough solar energy: units will start using power from the electrical grid to charge.

Conventional vs Hybrid reliability

Conventional AGL is energized by electrical circuit that includes multiple elements such as: lighting fittings constant current regulators, isolating transformers, primary cable, secondary cable, joints, etc. Yes – conventional lighting today is built of reliable components. But as with every reliable components – failure one component may lead to failure of entire or part of the lighting system. In case of H-AGL: system is built of separate units. If two or more units are off – the rest of the system will continue to operate.

Control independent from the power

Conventional AGL is controlled by changing current flowing via cable. If there is no electricity in the circuit Or circuit lost its capacity to transmit current – there is no way to control lights. S4GA H-AGL is controlled wirelessly (via encrypted radio-network). It means that power and control of the system are two separate systems. If one or even few lights are off – you can still control the rest of the system as there is no connection between power and control.

Thinking in an old-pilot way we of course assumed worst case scenario and asked ourselves “what if wireless control would fail”. To address this issue: each lighting unit is equipped with physical on/off button that allows to activate each unit manually. If wireless control is off – this is an emergency and you can still use system by activating each light individually.

Conclusions

Many features of H-AGL makes it significantly more reliable and maintenance-friendly than conventional AGL. H-AGL is not for every airport but many airports in the World today could benefit from using H-AGL instead of conventional lighting.