Railway Signalling Cables

Ever growing availability requirements for the operational rail lines and the decreasing MTBR (Mean Time Between Repair) for most of the railways ( in some cases its even less than an hour to rectify the fault) making signaling components requirement more robust and 'maintenance free' as much as practically possible during signaling life spa. Signalling Cables are one of the major component requires longer replacement time compared to any other signaling components during failure or first order or second order maintenance.

Due to seepage reasons tunnel also could be flooded to make the cable requirement similar to the cable in open trenches with submersible conditions.

Main Cables

As defined by the British practice, Main cables are the cables originating from Signalling Equipment Room to the Trackside boxes next to the end gear.These cables shall be armoured single stranded (class 1) /Multi stranded (Calss 2 ) based on application to protect from abrasion.

Tail Cables

Cables from disconnection boxes /junction boxes near the end gear (Signal Mast base box for Example ) to the end gear cables are tail cables.This can be non armoured, Class 1,class 2 or class 5 based on flexibility requirement.(It might be class 1 based on application signa frequency)

Indoor Cable

Cables which are "clean " (surge free ) originating from cable frame (Intermediate Termination Box) to the signaling cabinets.

Cable Frame segregate outdoor "Dirty" cables (with the help of Surge Arrestor and Lightning arrestor ) to Indoor cables.Indoor cables are usually multi stranded (Class 5) with or without braided shield or aluminum shield depends on application.

Control Cable

Control cables are used for controlling the end gear, it could be carrying 24/48V DC or audio frequency depending on the application.Cables carrying low voltage or medium voltage and are class 1 or class 2 or class 5 depends on application.Main cables shall be armoured where as tail cables could be non armoured.

Power cables

Cables carrying low voltage or medium voltage and are class 1 or class 2 or class 5 depends on application.Main cables shall be armoured where as tail cables could be non armoured.

Communication Cables

Data transfer cables falls under this category which include cat 6 copper cable, Fiber Optic cables etc. Again Main cables shall be armoured where as tail cables could be non armoured.

IEC Standards

IEC stanadrds are more popular among many countries, however American and British and even German stanadrds are also applied depends on countries.(Philippines follow NFC stanadrds for Anti Fire Properties )

Water Blocking Properties

Longitudinal and Transversal water blocking properties are well suited for cable vulnerable to flooding.Two layers of Swellable Water Blocking Tapes are encircled around cable construction with the first layer of tapes around wires and second layer around cable armour.The protecting factors includes, XLPE (cross linked poly ethylene) outer jacket, two layers of water blocking tape, insulation of the conductors and armour in some case (if its corrugated steel armour which are thermos welded around the cable formation ).Swellable tape act as a expandable bed and the jelly absorbs water from the moisture there by protecting moisture absorbed into the bare conductor. Standard EN 50289-4-2A defines the requirements and test for Longitudinal and Transversal water tightness test alternatively its defined in EN 50288-1 and EN 50288-7 for Longitudinal water tightness and IEC 61156-1 for transversal water tightness.Requirements for water absorption are defined in IEC 60811-402.Satisfactory test according to these standard will ensure a water fail proof signaling cable.

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