Arrow short circuit

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The arrow short circuit is a common form of representation in German-speaking countries for electrical circuits in railway safety technology . It was developed in 1900 by Robert Pfeil , an engineer and later board member at Siemens & Halske . A ladder diagram is a similar representation for programmable logic controllers .


Compared to the electrical usual circuit drawing of the pfeilsche short circuit has been rationalized shown by the following change:

  • Cutting open the circuits: The drawing is usually from top to bottom, the circuit is not shown closed.
  • Spatial separation of coil and contact: The assignment of the contacts to individual relays is indicated by the corresponding relay symbol or the designation next to it (no connection line between coil and contacts)
  • Energy supply: arrow drawn on the current path into it
  • Ground: arrow at the end of the current path out of this
  • Closed switch (NC contact): the line touching a horizontal line
  • Open switch (closer): the line cutting cross line
  • Relay coil: circle

Circuit symbols

The representation of electrical circuit diagrams in railway safety technology is similar to the ladder diagram of programmable logic controllers . The assignment of the contacts to individual relays is indicated by the relay symbol or the designation next to it. It should be noted that the circuit diagram does not reflect the de-energized state, but a basic position that is safe in terms of signaling .

Connection path

This marking depends on the manufacturer and type. The company Siemens uses this presentation:

bold line: switching within a relay group

thin printed line: free circuit

In the case of the WSSB designs , thin lines indicate standardized group internal circuits carried out in the manufacturer's works as well as system cabling that can only be laid on the building site, such as room cables, whereas bold printed free circuits are made on the building site. Changed internal circuits in relay groups, which then no longer correspond to the delivery condition, are also marked in bold.

Infeed and return

character description
Feed.svg Energy feed
Rückleitung.svg Return / ground


character description
Switch basic position open Contact, open in basic position
Switch normally closed Contact, closed in basic position


character description
Relay coil home position dropped out Relay coil, armature dropped out in basic position
Relay coil basic position tightened Relay coil, armature tightened in basic position
This does not require that the coil has current flowing through it. The anchor can also be pressed mechanically.

Individual evidence

  1. ^ Hans-Christoph Thiel: Data on the history of the railway system and railway technology. ( Memento of the original from October 6, 2014 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 196 kB), September 19, 2011. @1@ 2Template: Webachiv / IABot /
  2. ^ Ulrich Maschek: Securing rail traffic. 2012.