What types of Railway Cables are used on and around the track?
Click below to explore the interactive image showing cables used on and around the track.
- Signalling A1, Signalling A2 and Signalling A3: Generally speaking, this type of Signalling cable is used for free wiring in Relay Rooms, Signal Boxes, REBs (Equipment Boxes) and Location Cases. All Type A Cables have Class 2 stranded tinned copper conductors and are insulated with a flame retardant LSZH (Low Smoke Zero Halogen) compound. A1 and A2 Cables are single core cables and A3 Cables are multi-core. A2 and A3 Cables also have an LSZH sheath. These light-duty Signalling cables are generally for internal use – a smooth sheath makes them suitable for installation in ducting and between other cables.
- Signalling B1, Signalling B2, Signalling D1 and Signalling D2: Type B and D Signalling Cables are used between Equipment Boxes, Signal Boxes, Relay Rooms and Location Cases to connect up signal equipment. They are found in external cable troughs or attached to cable posts and provide control and signal transmission – although 2-core B2 Cables (10-95mm²) provide power for the signalling network in trackside situations. B1 and D1 Cables are used for maintenance within networks that comprise of B2 and D2 Cables. Both B and D Cables have Class 2 stranded tinned copper conductors – B1 and D1 Cables are single core cables and B2 and D2 Cables are multi-core cables. Whereas B1 and B2 Cables have EPR (Ethylene Polypropylene Rubber) insulation and HDPCP (Heavy Duty Polychloroprene) sheathing, D1 and D2 Cables have LSZH or EPR insulation and LSZH sheathing. Type D Cables are used in place of Type B Cables in tunnels greater than 200m in length – and locations designated as underground such as Birmingham New Street Station.
- Signalling C1, Signalling C2, Signalling E1 and Signalling E2: Type C and E Signalling Cables are designed to carry control and signal information between the Location Cases and the Signalling Head. They often sit on the Ballast (stones within and around the sleepers – there’s a train specifically designed to clean it) or can be clipped to cable posts. These single and multi-core heavy-duty cables do have the same insulation and sheathing as Type B and D Cables – Type E being the LSZH version – but they have flexible Class 5 stranded tinned copper conductors. C2 and E2 Cables are commonly referred to as Tail Cables. C1 and E1 Cables are used for the maintenance of these installations.
- Signalling C3 and Signalling E3: Designed for use in the rail network’s TPWS – or train protection warning system – these cables have two flexible cores with either EPR (C3 Cable) or LSZH (E3 Cable) insulation, a drain wire, and an aluminium screen.
Network Rail product acceptance is vital on safety-critical cables – including all Signalling cables
Points Heating Cable
Points along a railway line allow the train to change between tracks. It is vital that these Points continue to operate effectively in adverse weather conditions. To do so, Points Heaters are installed – along with Points Heating Cable. This heavy-duty cable consists of Class 5 flexible tinned copper conductors, EPR (Ethylene Polypropylene Rubber) insulation and a PCP (Polychloroprene) sheath, and provides power and control in Points Heating systems. Junction Blocks are also used for power distribution in Points Heating schemes.
- MV Power Cable: This 33kV cable – with solid aluminium or stranded copper conductors, a semi-conducting XLPE (Cross-Linked Polyethylene) conductor screen, XLPE insulation and semi-conducting XLPE insulation screen, water blocking tape, a copper wire screen (with Copper Equalising Tape) and a graphite coated MDPE (Medium Density Polyethylene) sheath – is used to provide AC power between the National Grid and Substations. (1x240mm² solid aluminium, 1x185mm² solid aluminium and 1x300mm² stranded copper are commonly used). MV Power Cables undergo what is called a Spike Test.
Watch the Spike Test video.
- Trackfeeder Cable: At a Substation, the AC current is transformed and rectified into DC 650/750V. To take the DC from the Substation to the track – where a third rail powers the network – Trackfeeder Cable is used. This power cable has a Class 2 stranded aluminium or tinned copper conductor, a PETP (Polyethylene Terephthalate) separator and a black CSP (Chlorosulphonated Polyethylene) sheath. (1x1000mm² stranded alumimium and 1x800mm² stranded aluminium are commonly used.)
- Medium Voltage Overhead Line: In overhead line systems, where there is no third rail, MV cables supply power to trackside gantry equipment to feed the bare copper overhead wires installed above the track. These cables power the train via a Pantograph – a device that sits on top of a train and collects the electric current from the bare copper wire.
- 11kV Cable: Armoured 11kV Cables are used to distribute power between substations. Over longer distances, 33kV Cable is generally specified. Both cables have Class 2 stranded plain copper conductors, XLPE insulation, a number of screens – including a copper tape screen – aluminium or steel wire armour and a red or black PVC sheath. A LSZH version of 11kV Cable, with LSZH bedding and a red or black LSZH sheath, is also available.
- SWA Cable: For the supply of power to parts of the network not listed as trackside, installers will often use SWA LSZH Cable. Both SWA PVC Cable and SWA LSZH Cable have Class 2 stranded copper conductors, XLPE insulation and aluminium or steel wire armour – depending on whether it is a single or multi-core cable. More detailed information on SWA Cable.
- Aluminium Power Cable: Aluminium Power Cable is designed for the distribution of trackside signalling power. Approved to BR880, this power cable has a sector shaped solid aluminium conductor, XLPE or PVC insulation, a PETP separator and a black PVC sheath.
Communication along the railway happens via a FTN or Fixed Telecom Network. This connects everything from Stations and Relay Rooms to telephone points in Location Cases. Both fibre and copper telecom cables are located in the cable troughs found along the side of the track. Copper Trackside Cable has Class 1 solid plain copper conductors, PE insulation, a petroleum jelly water-blocking compound, separator, moisture barrier and a black PE or LSZH sheath (there is also an armoured version with corrugated steel or polymer laminate tape). Fibre Trackside Cable and Armoured Fibre Trackside Cable are also used within the rail network for systems with high traffic and data requirements. Both cables have a single mode fibre, single continuous non-metallic strength member, a water-blocking compound, fibre carrier, separator and a PE sheath (the armoured version also has corrugated steel/ polymer laminate tape for mechanical protection).
Bare and Screening Conductor Cable
In overhead line networks, electrical interference caused by the potential of a high voltage cable can interrupt communications in telecom cables. To soak up the magnetic field generated by the overhead line cables and minimise the effects of this interference, Bare and covered Screening Conductor Cables are installed. Screening Conductor Cable has a single core stranded aluminium conductor and a black PVC or LSZH sheath, and a Bare Conductor consists of a single core stranded aluminium conductor. Screening Conductor Cables are often referred to as FTN Screening Conductor Cables – although you will see different Rail catalogue numbers assigned to them by Network Rail.
RIA21 and NSGAFOU Cable
It’s not just cables situated on and around the track that are vital to the smooth running of the rail network. The train itself is packed with cables, to ensure it operates efficiently. This includes RIA21 Cable and NSGAFOU Cable, both of which are installed in the electrical traction units that power the wheels and auxiliary controls (such as breaks and heating systems). RIA21 Cable has Class 5 flexible tinned copper conductors, a PETP separator, Composite Rubber insulation and a Black Composite Rubber Sheath. NSGAFOU Cable is a single core cable with a Class 5 flexible tinned copper conductor, EPR insulation, and a Black PCP sheath. These cables are used for existing maintenance and are no longer installed in new trains.
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