Airport Runway Lighting Systems

Idec Technical Products - components for ground lighting systems - various airports

A.C. Link Box

Our most recent product is the A.C. Link Box which was developed by Idec as a result of discussions with senior airport officials regarding the replacement of runway link boxes.

Idec has subsequently designed a new unit which has the following benefits compared with the original boxes:-

  • Simple to reconfigure with a 'Plug and Socket' arrangement.
  • Easy access hinged lid design.
  • Greater all weather protection - pressure balancing to eliminate water ingress.
  • Vastly reduces maintenance times.
  • Minimises electrical leakage resulting in constant light intensity and reduced power consumption.

System Description

Airport runway lights are wired in strings of about 10-12 lights in series. The whole string is fed from a constant current source set to deliver up to 12 amps at up to 1500v, 50Hz AC RMS, depending on the brilliance required.
Each light in the field is fed via an individual transformer so that if a bulb fails the remainder of the string will continue working. If an individual bulb does fail, intervention of staff is required to repair the faulty bulb.
If the airport staff wish to ensure that an aircraft cannot use a metalled area that is closed off for maintenance etc, they extinguish the strings of lights leading to that area by disconnecting the appropriate link at the Link Box.

Purpose

The purpose of the AC Link Box is to select each lighting string 'In-Circuit' or 'Isolated' as required. A lighting string that is 'Isolated' will not receive power while one that is 'In-Circuit' will.

With any combination of 'In-circuit' or 'Isolated' selections, the Link Box will not introduce an additional loop resistance of more than 0.2 ohms.

At all times, the leakage current from the 1500v supply to the earth via the stainless steel enclosure does not exceed 5 micro amps. When a string is isolated by changing the plug position, the leakage current from the 1500v supply to the isolated string does not exceed 2 micro amps.

At these maximum current levels, the airport maintenance crew will be able to work safely on the isolated field cables while the rest of the strings are connected to power.

Basic Construction

The Link Boxes are constructed from 2mm thick 316 Stainless Steel, to I.P.66 as standard and have a lid, hinged at one end with the other end secured by bolts.

Even enclosures with high I.P. ratings become damp inside after a period of use, possibly due to temperature variations sucking in damp air around any transitions. To prevent this a ventilator plug is fitted to prevent over and under pressurising of the box. This ventilator will not allow liquid to enter, but allows air to flow either way. The 'Socket' and 'Plug Block' mouldings are designed to minimise/eliminate the effect of moisture droplets

The Socket and Plug Block mouldings have very low shrinkage and exhibit a smooth low-profile surface with excellent appearance and gloss. It has high tracking resistance and absorbs a minimal amount of water.

The units have been electrically tested by an external body (Volkor) and will be CE marked by way of a technical file.


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