26-07-2011, 07:54 AM
Indeed ;the TCI will have its own circuit.
This re[presents current standards for any form of track circuit.
Howver tt has to be the case for TI21, since these work at audio frequencies and therefore any track circuit jumpers are far more significant; whereas for a dc or 50Hz ac track their resistance is not too significant, at frequencies around 2kHz then the inductive impedance begins to make a difference.
In particular most TIs are used in jointless configuration and the length of the rail leads between the actual rail and the tuning unit is critical.
This re[presents current standards for any form of track circuit.
Howver tt has to be the case for TI21, since these work at audio frequencies and therefore any track circuit jumpers are far more significant; whereas for a dc or 50Hz ac track their resistance is not too significant, at frequencies around 2kHz then the inductive impedance begins to make a difference.
In particular most TIs are used in jointless configuration and the length of the rail leads between the actual rail and the tuning unit is critical.
(26-07-2011, 05:07 AM)Archie Wrote: so what it is you are saying that the interruptor has it's own circuit rather than being in series with the track circuit itself, but what do you mean by the impedance?
Many thanks
PJW