"UTRL"--AN ELECTRONIC FAIL-SAFE LOGIC IN RAILWAY SIGNALLING
The author begins by explaining the indispensable failsafe requirements of a railway signalling system and how they have been develop from the first mechanical interlocking boxes to the semi-conductor electronic equipment now in use. He then describes how the URTL, which is a dual-channel system, achieves almost total positive security by means of: twin switching units operating in antiphase; comparison of the state of the twin switching units; clockpulse checking of the state of the units; basic elements comprising two identical majority logics; control transducers permeable to signals only if a certain Boole algebra chain is established. A functional unit comprises 30 integrated basic elements assembled on a standard logic printed circuit card.
- Paper read at the IRSE in Brussels on 21/2/75 on the subject of a Siemens electronic logic designated URTL (Uberwachbare Resistor Transistor Logic).
Institution of Railway Signal EngineersLondon, England
- Lohmann, H J
- Publication Date: 1975-2-21
- Features: Figures;
- Pagination: 11 p.
- TRT Terms: Fail safe systems; Signal devices; Traffic signal control systems
- Old TRIS Terms: Signal systems
- Subject Areas: Railroads; Safety and Human Factors;
- Accession Number: 00126992
- Record Type: Publication
- Source Agency: International Railway Documentation, Selection of
- Files: TRIS
- Created Date: Nov 18 1975 12:00AM