The tone-frequency microprocessor track circuits MRC-U are designated to monitor occupancy/vacancy of track sections at stations and spans, to monitor integrity of track circuits, to transmit code signals of ALS from wayside devices to a locomotive.

A track circuit power supply module (MPRC) is a combined device containing the following:

  • an RC power supply node (a tone-frequency signal generator);
  • a two-channel RC monitoring node;
  • an ALS code generator node

In the “generator” mode MPRC carries out design of tone-frequency signals and ALS code signals, generating a sum signal of power supply and ALS at the output. In the “receiver” mode, the module carries out simultaneous measurement of levels of two frequency signals and their comparison with a specified setpoint.

A track circuit control module (MKRC) is designated to monitor uncoded branches of track circuits. It contains three independent two-channel RC monitoring (voltage measurement) nodes.

In MPRC and MKRC the same solutions are used as in the object controllers of MPC-U (two diverse channels, operation according to the “2oo2d” scheme).

System advantages

  • supplying power, monitoring, and coding track circuits without use of relay equipment;
  • parameters of signals of TRC and ALS don’t depend on changes of climatic conditions;
  • high noise-immunity of receiving equipment, due to digital filtering;
  • continuous diagnostics of receiving-transmitting nodes by means of measurement of parameters of signals being shaped;
  • possibility of redundancy of MPRC and MKRC (“hot” redundancy);
  • availability of interfaces for coupling with any type of EC;
  • resistance to lightning and switching overvoltages;
  • use of MRC-U based on digital signal processing assures the following:
  • continuous monitoring of cable parameters;
  • continuous monitoring of track circuit parameters (including assessment of residual voltage, track circuit integrity, insulation failure of an insulated joint, monitoring of occupancy of diverging branch lines) without additional equipment;
  • stable operation of track circuits in case of asymmetry of traction currents up to 50 А, which corresponds to real parameters of asymmetry at railways with the “1520” track;
  • absence of necessity of season regulation of track circuit parameters;
  • reduction of human factor influence onto rail traffic safety due to a safe function of automated adjustment of track circuit parameters.

Technical characteristics of MRC-U



   Length of a track circuit

   From 25 m to 1500 m (depends on track line insulation resistance and track circuit configuration)

   Additional shunting zone

   From 0 to 40 m

Structure of MRC-U

SRPA “Impulse” is a leading Ukrainian designer, manufacturer, and supplier of highly-reliable instrumentation and control systems for nuclear power engineering and railways.