Maximum section length with occupancy detector

Verwendung

Maximum section length

Section longer than 7 meters

Due to electrical interference, excessively long sections should not be used. Reporting sections longer than 7m are not possible (at least with Littfinski).

Monitored track sections

Quote from a message:

   Isolated track sections that are to be monitored
 from the perspective of track occupancy detectors, have inductive
 and capacitive components that, depending on the length
 of the section, cause increasing electrical
 background noise.
 From a monitored length of several meters, this leads to a continuous occupancy indication, even if
 no electrical load is present on this section.
 This applies to all track occupancy detectors, regardless of the manufacturer. The mentioned 7m is
 a perfectly realistic length.
 .
 Best regards
 .
 Peter Littfinski

Are all manufacturers affected?

No, that does not apply to all manufacturers.

The reason for this 'self-occupancy' lies in the nature of the control signals used. Both DCC and Märklin/Motorola use a positive-width encoded voltage; whenever the polarity of the signal changes, a small charging current flows briefly into the line capacitance – this current is greater the longer the connected line.

With simple occupancy detectors, the average current consumption is simply measured; therefore, an occupancy report is generated above a certain length, even without an actual consumer present.

If, on the other hand, the occupancy detector evaluates the track signal, synchronizes to it and 'looks away' very briefly during the polarity reversal (only a few µs), then only actual consumption is measured and influences of line or track length are eliminated.

This information was published in a post in the forum.

Weblinks

• Quelle: Forum

-- UP4001 10:03, 28. Jan. 2012‎

bearbeitet: Uslex (Diskussion) 14:37, 30. Mai 2022 (CEST), Uslex (Diskussion) 14:04, 10. Dez. 2025 (UTC)