STATION RAIL CHAINS
The study of the features of station rail circuits (RC) and the requirements for modern operating conditions.
Acquaintance with the main types of RC, used for autonomous and electric DC and AC.
The study of methods for isolating switches and features of branched RCs.
Analysis of the work of branched RC in damage.
Appointment and classification of station track circuits
The main purpose of station electric rail circuits is to monitor the employment or free status of isolated track sections located within the station.
Under insulated track sections are understood as ways of receiving and departing trains, sections of tracks in the necks of stations with and without arrows, isolated with the help of insulating joints into independent electrical circuits.
Electric RC is the main travel sensor in all modern automatic and telemechanical systems for controlling the movement of trains in railway transport.
In the station systems of centralized control of arrows and RC signals, you can:
establish train and shunting routes subject to obtaining reliable information about the freeness of isolated tracks and switch sections in the zone of movement;
to exclude the transfer of centralized shooters under the composition, as well as the cutting of the route before its actual release;
continuously monitor the state of the station tracks and switch stations on the console;
transfer to the locomotive operational information about the status of the forward-looking traffic light when the train is moving along the main and some lateral paths of the stations;
increase the constant monitoring of rail track integrity.
Due to the specific features of the stations and the complexity of their development, station RCs differ from distillation schemes by including track receivers, the large instability of the electrical parameters of the rail line, the presence of serial and parallel branches, a slight length within the switch and trackless sections, the choice of methods for channeling traction current and others
In order to fulfill the necessary dependencies, in the executive circuits of centralization of arrows and signals, the traveling receivers of station circuits, together with other relay equipment, are usually located at centralization posts. In this regard, the most widely used at stations are alternating current centers, where due to the use of matching relay transformers or choke transformers with a high transformation ratio, a large voltage drop in the connecting wires is eliminated and it becomes possible to locate the equipment at significant distances from the ends of rail lines without cable core duplication.
Depending on the track development of controlled areas, station RCs may be unramified or branched with special isolation schemes and the inclusion of track receivers. In turn, they are classified according to the type of traction, the method of sewage of the reverse traction current, the need to impose automatic locomotive signaling devices, the type of supply current, the method of controlling short circuits of insulating joints, protection of traveling receivers from dangerous and interfering influences of various kinds of interference.
For example, according to the presence and method of sewage of the reverse traction current, the station chains can be divided into three large groups: RC for areas with autonomous propulsion RC for areas with DC electric; RC for areas with AC electric current. At the same time, depending on the method of sewer traction current, the RC of the last two groups is divided into single-thread and double-thread, in which, respectively, one rail thread – traction or both threads – are extracted to skip the reverse traction current.
The presence of electric traction, the type and method of sewer traction current greatly complicate the design and design of all elements of the station RC, increase the number of their types and require the use of special protection against the influence of traction current and its harmonic components. In this regard, in each case, the signal current frequency of 25 or 50 Hz is used. In addition, the inclusion of various filters can be used, continuous or pulsed power supply, as well as phase-tracking receivers with amplitude, phase and frequency selectivity properties can be used.
The following requirements are imposed on the station RC due to the specific conditions of their operation:
trouble-free operation in a real-life range of conductor rail insulation;
high reliability of protection of traveling receivers against interference from traction current and other sources;
accelerated response of the circuit to the effects of train shunt;
profitability both in equipment costs and operating costs.