LU84981A1 - TRACK CIRCUIT FOR TRACK MONITORING IN RAILWAY LOCKING SYSTEMS - Google Patents

Description

SIEMENS AKTIENGESELLSCHAFT Our mark:

Berlin and Munich VPA 82 P 2 9 3 3 DE

5 Track circuit for track monitoring in railway protection systems

The invention relates to a track circuit for track monitoring in railway safety systems, 10 in which a transmitting device transmits an AC voltage to a receiving device via a track section, which evaluates the received AC voltage using a comparison AC voltage at least according to size.

15

In railway safety systems, isolated track sections are used for track monitoring, the rails of which are connected at one end to, for example, an AC voltage source, while at the other end 20 a receiving device is provided, for example a motor relay, which reports the free or occupied condition of the track using the comparison AC voltage . The evaluation of the alternating voltage supplied to the motor relay is carried out according to amplitude, frequency and phase position. The motor relay is pulled up when the track is clear; it drops if the rails are short-circuited by vehicle axles when the assigned track section is occupied. Instead of motorized relays, other 30 phase-sensitive track relays can of course also be used. Such known devices have been described many times, cf. DE-PS 1 271 749.

AC track circuits with phase-selective 35 relays, however, are subject to electromagnetic interference from reverse currents and their harmonics.

HSH-6-Fa / 1,9.82 t

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The influencing problems have become more acute with the introduction of traction vehicles with thyristor control in phase-section, three-phase and chopper technology and with the high drive power that has become common today. In the case of 100 Hz track circuits, the sixth harmonic of the 16 2/3 Hz traction is particularly disruptive. A critical interference is given when the track section in question is occupied in the area of the transmitter, i.e. on the feed side, 10, so that the AC voltage resulting from an interference current can reach the receiver, i.e. the track relay, undamped. The interference voltage can assume the level of the usable voltage present in the case of a free track section with a matching frequency, so that an impermissible free signaling of the track section in question can be expected. Now the phase selectivity of the receiving device used (track relay) already provides a certain protection against harmful external voltages, since the track relays generally have a limited working range within the phase position of the AC voltage supplied to the track circuit and the phase position of the comparative AC voltage. The motor relay has a working range of 25 60 ° to 120 °. In this way, only interference voltages that lie in the ’angular range with regard to their phase position can become dangerous.

The invention has for its object to improve a track 50 circuit of the type mentioned in such a way that immunization occurs with respect to the harmonics triggered by the traction, without having to drive a remarkable additional technical effort.

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Sr.

According to the invention, the object is achieved in that the alternating voltage of the transmitting device and the comparative alternating voltage are routed 5 via switching devices synchronously controlled with a predetermined period duration, such that the alternating voltage and the comparative alternating voltage are constant with respect to one another with respect to their phase positions, but differ from one another with respect to the phase position change other AC voltage suddenly with the specified period.

10th

This proposed solution is based on the knowledge that the track relays have a predefined starting time TA and that the fault durations determined so far are greater than this value of the starting time. The period-15 duration for synchronous control of the switching devices mentioned is advantageously made smaller than the value TA, e.g. 0.5 TA.

An advantageous embodiment of the invention provides that the switching devices are designed as pole reversing circuits, which are each connected on the input side to two rails of a multiphase network.

A

However, it is also advantageously possible to use a switching device which is connected to an n-phase network and has n output terminals which are cyclically connected to the n phases of the network with the aid of a number of n2 switching elements, the alternating voltage and the Comparative AC voltage 30 are tapped between two of the output terminals.

Another advantageous embodiment provides that two transformers 35 are connected to an n-phase network, each between identical outputs

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Have voltages with a phase shift of 180 ° that changeover contacts are connected to the outputs of the transformers, such that the alternating voltage and the comparative alternating voltage ab-5 are alternately taken from one or the other transformer.

Several exemplary embodiments of the invention are shown in the drawing and are described in more detail below.

Show it:

FIG. 1 shows a track circuit in which the alternating voltage and the comparative voltage are supplied with the help of two RDlwæde circuits,

2 shows a switching device that allows a cyclic phase advance for the AC voltage and the comparison AC voltage, and FIG. 3 shows a switching device that, in conjunction with two transformers, brings about a cyclic phase reversal for the AC voltage and the comparison alternating voltage.

25th

The upper part of the block diagram according to FIG. 1 shows a section of a route which can be traveled in the direction of travel F with a single-rail insulated AC track circuit GS. The required track alternating voltage 30 is taken from a three-phase network RST and fed to the two rails S1 and S2 of the track circuit GS via a switching device SG1 and a transformer T1_. At the end of the track circuit GS, the crawl voltage present on the free track is changed to a phase-sensitive one with the help of the transformer T2

Track relay GL given, which for comparison purposes

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receives a comparison AC savings from the three-phase network RST. This comparative AC voltage is passed through a further switching device SG2.

This and the switching device SG1 are constructed in the manner of a pole reversing circuit. The contacts X1 to X4 of the switching device SG1 and the contacts Y1 to Y4 of the switching device SG2 are actuated synchronously by a control device ST with a predetermined period. This period is preferably set 10 so that it is less than the value of the pull-in time TA of the track relay GL, for example 0.5 TA. Thus, the switching devices SG1 and SG2 continuously cause the phase position of the alternating voltage supplied to the track circuit GS and the comparative alternating voltage offered to the track relay GL to be switched suddenly by 180 °.

Due to the measures described above, the track relay GL now receives a voltage component when the track circuit GS is influenced by an interference voltage, which initiates a drop-in torque, so that no impermissible free signal from the occupied track circuit GS can occur.

The voltage supply via the terminals K1 and K2 or K3 and K4 can advantageously also be carried out by [a circuit arrangement according to FIG. 2. For this purpose, for example, terminals K1 and K2 are connected to terminals K6 and K5 and terminals K3 and K4 30 to terminals K7 and K5. The same reference numerals have been provided in the arrangement according to FIG. 2 for system parts already described.

For decoupling, a transformer T3 is connected to the three-phase three-phase network RST, on whose 35 secondary windings T31 »T32 and T33 one through

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Control device ST actuated switching device SG3 is. The switching devices SG3 have the task of cyclically feeding the three AC phases of the three-phase network to the three terminals K5, K6 and K7.

5 For this purpose, terminal K5 is cyclically connected to windings T31> T32 and T33 via contacts Z10, Z20 and Z30. The same applies mutatis mutandis to terminals K6 and K7 and the contacts Z11 to Z31 and Z12 to Z32 assigned to them. These individual contacts 10, which may belong to relays, for example, not shown, are cyclically actuated by the control device ST in synchronism with the above-mentioned period. In this mode of operation, the contacts Z10, 15, Z11 and Z12, which were still closed at the time of observation, are then opened and the contacts Z20, Z21 and Z22 are closed. The latter contacts then open and contacts Z30, Z31 and Z32 close. The circuit state shown is then repeated. Due to the cyclical phase advancement thus achieved, the phase position between the alternating voltage supplied to the track circuit GS (FIG. 1) and the comparative alternating * voltage for the track relay GL remains constant; however, the phase position of both voltages changes periodically 25 in steps of 120 °.

Instead of the circuit arrangement according to FIG. 2, the one according to FIG. 3 can also be used. This circuit arrangement causes a cyclical phase reversal for the voltages supplied to terminals K1 and K2 30 or K3 and K4 in the arrangement according to FIG. The track circuit GS (Figure 1) is connected to terminals K8 to K10 via terminals K1 to K4. In particular, two transformers T4 and T5 are provided,

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which are connected on the primary side to the three-phase three-phase network RST. As the illustration shows, the two transformers T4 and T5 are connected differently on the secondary side, such that the AC voltages of comparable output lines, e.g.

of the lines L1 and L10, have a phase shift of 180 ° to each other. This applies to transformers in vector groups DY5 and DY11. The switching device SG4 10 provided in this exemplary embodiment has the task of providing the alternating voltages required for the track circuit GS (FIG. 1) with the specified period duration alternately from one or the other transformer T4 or T5. For this purpose, three pairs of changeover contacts 15 U1, U2 and U3 are provided, which are actuated indirectly by the control device ST with the above-mentioned period.

The device according to the invention can also be used advantageously in power supply networks which have a different number of phases than n = 3.

4 claims 3 figures

Claims (5)

1. Track circuit for track monitoring in railway safety systems, in which a transmitting device 5 transmits an AC voltage to a receiving device via a track section, which evaluates the AC voltage received using a comparison AC voltage at least according to size, characterized in that the 10 AC voltage of the transmitting device (T1) and the Comparative AC voltage are routed via switching devices (SG1, SG2) controlled synchronously with a predetermined period, in such a way that the AC voltage and the comparative AC voltage are constant with respect to one another in terms of their phase positions, but change abruptly with respect to the phase position of another AC voltage with the specified period duration. 20 2, track circuit according to claim 1, characterized in that the switching devices (SGl / SG2) are designed as pole reversing circuits, each of which is connected on the input side to two sections of a multiphase network (RST) (Figure 1). 25th 3. Track circuit according to claim 1, characterized d'urch by a to an n-phase network (RST) connected switching device (SG3) having n output terminals (K5, K6, K7), which with p 50 With the aid of a number of n switching elements (Z10 to Z30; Z11 to Z31; Z12 to Z32) are cyclically connected to the n phases of the network (RST), the alternating voltage and the comparative alternating voltage in each case between two of the output terminals (K5, K6, K7 ) 55 is tapped (Figure 2). -9- vpa 82 P 2 9 3 3 DE 4. Track circuit according to claim 1, characterized in that two transformers (T4; T5) are connected to an n-phase network (RST), each between identical outputs (L1, L10) 5 voltages with a phase shift of 180 ° that switch contacts (U1, U2, U3) are connected to the outputs of the transformers (T4, T5), such that the alternating voltage and the comparative alternating voltage alternately one or the other 10 transformer ( T5, T4) are removed (Figure 3). A