SPFB Speed Control System Cables


The cables are used for the train speed control system (French system KVB). The cables are laid along railway lines and connect the speed sensors (located between the rails) to the encoder located inside the trackside equipment shelter.


  • SNCF CT 446

Cable Construction

SPFB Speed Control System Cables Railway Cable
Conductors Class 2 stranded tinned copper.
Insulation Solid polyethylene.
Cabling Element Twisted pair.
Inner Sheath Low density polyethylene.
Armour Galvanized steel braid armour.
Outer Sheath Flame Retardant PVC.

Electrical Characteristics at 20℃

Nominal Conductor Diameter mm 0.8
Nominal Cross Section Area mm^2 0.5
Maximum Conductor Resistance (DC) Ω/km 36
Characteristic Impedance @100KHz Ω 120
Maximum Attenuation @50KHz dB/km 5
Nominal Insulation Thickness mm 0.55
Operating Voltage V 500

Mechanical and Thermal Properties

  • Minimum Bending Radius: 8×OD (static); 16×OD (dynamic)
  • Temperature Range: -30℃ to +70℃ (during operation); -20℃ to +50℃ (during installation)

Dimensions and Weight

Cable Code No. of cores& Nominal Conductor Cross Sectional Area No. & Nominal Diameter of Strands Nominal Sheath Thickness Nominal Overall Diameter Nominal Weight
Inner Outer
  No.×mm^2 No/mm mm mm mm kg/km
RS/SPFB-2Y2Y(SWB)2Y-2C0.5S 2 x 0.5 7/0.32 1.0 1.5 9.1 97