Pzb 500hz Question

Discussion in 'PC Discussion' started by breblimator, Sep 17, 2021.

  1. breblimator

    breblimator Well-Known Member

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    I have always been interested in the following case: 500Hz is on when I reach the clear signal. The magnet is not active at this signal. I pass over it and the 500Hz goes out. How does the train know about the inactive magnet (and turns off the 500Hz indicator)?* I am asking about the principle of operation. From a gameplay point of view, this does not bother me :) BR o7

    * some paradox for me
     
  2. Cramnor

    Cramnor Well-Known Member

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    The 500Hz turns off because you have travelled the 250m that it is active :)
     
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  3. involvedmass

    involvedmass Member

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    Interesting question...
    Found this
    If the signal changes to clear after we have passed the 500 Hz magnet, the 500 Hz speed limit (45 km/h) applies until 403 m after that magnet, at which point we can release ourselves. (During the 500 Hz speed control, no release is possible, but before or afterwards.)​
    https://www.sh1.org/eisenbahn/rindusi3.htm#ToClear

    Sounds like it's based on distance travelled, but in the game it clears right at the signal :|
     
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  4. involvedmass

    involvedmass Member

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    Also depends on if you have stopped by the looks of it, unless I'm misinterpreting it :D
    If the halt was after the 500 Hz magnet, after departure we would have to obey the restrictive 500 Hz-speed limit (25 km/h) for 200 or 250 m, then release ourselves from the (restrictive) 1000 Hz-speed limit.​
    https://www.sh1.org/eisenbahn/rindusi3.htm#Halt
     
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  5. Cramnor

    Cramnor Well-Known Member

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    And, what might be interesting for you, the PZB magnets are actually not the "active" part. The one sending the "waves" is the train, the magnets are passive units that resonate at the specified frequencies, which the train device can detect ;)
     
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  6. breblimator

    breblimator Well-Known Member

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    Man learns all his life :)
    Thanks, gentlemen. It was a solid learning experience \o/
     
  7. Monder

    Monder Well-Known Member

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    And what is the difference between the hot and cold magnets then? Is it the direction in which they reflect what changes when the signal is restrictive?
     
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  8. solicitr

    solicitr Well-Known Member

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    Magnets aren't directional; they are either on or not, and if they're on then the loco senses them when it passes over. The subsequent distance and any applicable speed restriction is calculated by the onboard PZB unit; the magnet senses nothing.

    Indusi after all is a very old, low-tech system, invented in the 1930s.
     
  9. Cramnor

    Cramnor Well-Known Member

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    In simple terms, when the magnet is "hot", a switch inside is open so that it will resonate at the specified frequency. When it is "cold", the switch is closed and it will lead to the magnet not resonating at the frequency.
    This system was already used with the old mechanical systems, hence it was designed in a way it can go without electricity. The switch can be linked to the mechanical signal in the old times (well, still plenty of that around these days :D) or is electronically operated nowadays. But it is the switch that is electrically operated, not the magnet and frequency response itself.

    From Wiki (lazy translation with Google Translate below):
    Am Gleis liegen die Gleismagnete, deren Spule zusammen mit einem Kondensator einen auf eine bestimmte Frequenz abgestimmten Schwingkreis bildet. Sie werden mit Gleismagnethaltern an der in Fahrtrichtung rechten Schiene auf der Außenseite befestigt und ausgerichtet.

    • Der 1000-Hz-Magnet an Vorsignalen oder Überwachungssignalen von Bahnübergängen überprüft das Aufnehmen der Warnstellung des Signals und das Einleiten der Bremsung.
    • Der 500-Hz-Magnet liegt 150 bis 250 Meter[5] vor einem Hauptsignal, das einen besonderen Gefahrenpunkt deckt. Er überprüft den Bremsvorgang auf eine festgelegte Geschwindigkeit und gewährleistet, dass die Schutzstrecke hinter dem Hauptsignal nicht unerlaubterweise überfahren wird.
    • Der 2000-Hz-Magnet an Hauptsignalen dient als Fahrsperre bei haltzeigendem Signal und löst sofort eine Zwangsbremsung aus.
    • 1000/2000-Hz-Doppelgleismagnete werden an Hauptsignalen mit Vorsignalisierung oder wenn am gleichen Standort ein Vor- und Hauptsignal steht, eingesetzt. Ihre Resonanzfrequenz kann durch einen zuschaltbaren Kondensator umgeschaltet werden. Praktisch sind alle neueren 1000- oder 2000-Hz-Gleismagnete Doppelgleismagnete. Wird nur die 1000-Hz-Funktion benötigt, dann wird der zusätzliche Kondensator mit einer einzulegenden Brücke fest in den Schwingkreis eingeschaltet. Bei reinen 2000-Hz-Magneten wird der zusätzliche Kondensator nicht beschaltet.
    • Schaltmagnete enthalten keine Kondensatoren, die Spule bildet keinen Schwingkreis. Sie lösen beim Befahren keine Beeinflussung der Fahrzeugeinrichtung aus, sondern werden für die Steuerung von Geschwindigkeitsprüfeinrichtungen genutzt.
    Die Gleismagnete sind in der Grundstellung oder unbeschaltet aktiv. Bei fahrtzeigenden Formsignalen wird der Gleisschwingkreis durch Kontakte von Flügel- bzw. Scheibenstromschließern kurzgeschlossen, bei Lichtsignalen durch Relaiskontakte. Damit wird der Gleisschwingkreis soweit verstimmt, dass keine Beeinflussung des Fahrzeuggerätes erfolgt.

    English:
    The track magnets are located on the track, the coil of which, together with a capacitor, forms an oscillating circuit that is tuned to a specific frequency. They are attached and aligned with track magnet holders on the right rail on the outside in the direction of travel.

    The 1000 Hz magnet on advance signals or monitoring signals from level crossings checks that the warning position of the signal has been picked up and that braking has been initiated.
    The 500 Hz magnet is 150 to 250 meters [5] in front of a main signal that covers a particular danger point. It checks the braking process for a set speed and ensures that the protective distance behind the main signal is not crossed without permission.
    The 2000 Hz magnet on the main signals acts as a travel lock when the signal indicates a stop and immediately triggers emergency braking.
    1000/2000 Hz double track magnets are used on main signals with pre-signaling or when there is a pre-signal and a main signal at the same location. Their resonance frequency can be switched by a switchable capacitor. Practically all newer 1000 or 2000 Hz track magnets are double track magnets. If only the 1000 Hz function is required, then the additional capacitor is permanently connected to the resonant circuit with a bridge to be inserted. In the case of pure 2000 Hz magnets, the additional capacitor is not connected.
    Switching solenoids contain no capacitors, the coil does not form an oscillating circuit. They do not influence the vehicle equipment when driving on, but are used to control speed test equipment.
    The track magnets are active in the basic position or not connected. In the case of form signals showing the way, the track oscillating circuit is short-circuited by contacts of wing or window current closers, in the case of light signals by relay contacts. The track oscillating circuit is thus detuned to such an extent that the on-board unit is not influenced.
     
    Last edited: Sep 17, 2021
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