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AP - AŽD - Switch VZ (50Hz - 75Hz)
The line train protection system (LVZ LS) works on the principle of so-called coding. Using track circuits, the signal character of the signal is transmitted to the track section in front of the signal via frequency coding of signals. There is a sensor on the vehicle in front of the first axle, which inductively detects this frequency, decodes it, and then transmits information about the signal to the so-called signal repeater at the driver's station. This informs the driver about the signal on the signal that is lit in front of the train. The first types of LVZ LS began to be tested in the 1960s and gradually progressed to the LS 90 system, which was installed from the 1990s.
Of the total length of the railway network of the Railway Administration, which has approximately 9,350 km of tracks, this system was implemented on approximately 1,500 km of tracks.
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This frequency is modulated by the encoder with rectangular pulses of the following repetition frequencies:
0.9 Hz for red light
1.8 Hz for yellow circle
3.6 Hz for yellow light
5.4 Hz for green light
The vehicle is equipped with code sensor coils on the bottom in front of the first axle. The code is evaluated and converted to a signal repeater. The meaning of the individual lights (signals) is as follows:
Red: The following signal is in the stop position. If the red light flashes, which is caused by code interruption, the signal is a repeated warning at the following signal. The signal prohibiting travel is then behind this signal at a distance less than the braking distance.
Yellow circle: The following signal orders to travel at a reduced speed.
Yellow: The train is approaching the signal in the warning position or expect a speed of xx km/h.
Green: The signal is free at the following signal.
Blue: No confirmation of the driver's alertness is required, i.e. the specified time has not elapsed since the last press of the alertness button, the train is braked by an additional brake or the train is in push mode. Except for the last case, the blue light is on simultaneously with the signal according to the transmitted code.
The track section is usually also used to detect the presence of a train in the section. In such a case, a signaling voltage is supplied between the rails, for example at 75 Hz, via a contact transformer at the beginning of the section and is detected by a contact transformer at the end of the section. When the voltage disappears, the section is detected as occupied, whether this occurred by shunting (connecting) the rails by the axle of a passing train, a broken rail in the section or another failure of the signaling device. This ensures safety. After experiences where a train stopped in a section and, for example, by pouring sand under the wheels during braking, lost contact with the rails, so that the section appeared to be free, another train drove there and a collision occurred, the section is detected as occupied until the moment when the train appears in the next section. When a train enters a section, instead of detection at 75 Hz, signaling at, for example, 275 Hz is connected, which already contains the state coding, see above. In the case of bidirectional sections, the coding is performed from the side where the train is traveling, since the receiving coils are in front of the front axle.External Content sketchfab.comContent embedded from external sources will not be displayed without your consent.Through the activation of external content, you agree that personal data may be transferred to third party platforms. We have provided more information on this in our privacy policy.