Axle Counter Cables
Axle counters are track-side devices that detect the passing of a train in lieu of the more common track circuit. The axle counter monitor and count the number of train wheels passing by them. A counting head (or 'detection point') is installed at each end of the section, and as each axle passes the head at the start of the section, a counter increments. A detection point comprises two independent sensors, therefore the device can detect the direction of a train by the order in which the sensors are passed. As the train passes a similar counting head at the end of the section, the counter decrements. If the net count is evaluated as zero, the section is presumed to be clear for a second train.
Axle counter cables are used to connect the track-side axle counters, which are usually positioned at intervals of between 1 and 3km, to the central monitoring system for determining train presence, direction of travel and number of wagons. Axle counter cables are usually armoured, jelly fi lled, PE insulated and sheathed cables used for transmission of signals up to 90 kHz in axle counter train detection systems. The applicable standards are RT/E/PS/00031 and NR/L2/SIG/30060.
Axle Counter cables are characterized by low reduction factor and offer a high level of shielding against the electromagnetic interference (EMI) produced by high-voltage overhead catenaries and other power feeds.
Typically, the operating signals from the axle counters vary between 60 and 90V, and a key requirement for this very demanding safety-critical application is that the axle counter cable should offer a low voltage drop, with a loss of just a few volts over long lengths. This is signifi cantly better than conventional signal cables. Further, Axle Counter cables give clear advantages in term of cable size and watertightness performance. The cables are compact in size and fl exible enough to enable it to fi t easily within the already crowded train axle counter systems.