03-10-2012, 02:47 PM
(03-10-2012, 01:47 PM)Shomel122 Wrote: Hi,
Im new to signalling and new to the railway. Just wondering how are DC track circuit powered. What are the fault indication if current, resistance or voltage were higher than normal?
Basic DC tracks are fed from a simple transformer rectifier. For typical values, see the range of TC calculation questions in the past IRSE papers.
Some older DC tracks will be fed from a single 1.2v cell. More modern ones have a supply voltage more in the range 10-20v.
Simple track circuits do not have any monitoring as such - the voltage levels are checked on routine maintenance and assessed by the technician. There is no condition monitoring as such. If the supply fails, or drops below the required level, the track relay would drop and the track would show occupied on the signaller's display.
Peter