interrupter unit
111A2 Key System — The 1A2 Key System is an analog multiline business key telephone system. Unlike more modern multiline systems, every telephone line serving a particular phone is wired into that phone, and electromechanical switches (the keys ) switch the lines… …
12North American railroad signals — Main article: North American railway signaling Baltimore and Ohio Railroad Color Position Light bracket masts at Magnolia, West Virginia North American railroad signals generally fall into the category of multi headed electrically lit units… …
13Otto Parschau — Photo of Leutnant Otto Parschau just after earning the Pour le Mérite …
14Protective relay — See also: Power system protection In electrical engineering, a protective relay is a complex electromechanical apparatus, often with more than one coil, designed to calculate operating conditions on an electrical circuit and trip circuit breakers …
15Tesla coil — at Questacon the National Science and Technology center in Canberra, Australia Uses Application in educational demonstrations, novelty lighting, as well as music Inventor …
16Western Front (World War I) — Infobox Military Conflict conflict=Western Front partof=World War I caption=For most of World War I, Allied and German Forces were stalled in trench warfare along the Western Front. place=Belgium and northeastern France date=1914 ndash; 1918… …
17Level crossing — This article is about at grade intersections between railway and road. For where two rail lines cross, see level junction. For a type of nuclear receptor (RXR), see Retinoid X receptor. A level crossing at Chertsey, England, as the barriers rise …
18Railway signal — Not to be confused with Railway signalling. A signal is a mechanical or electrical device erected beside a railway line to pass information relating to the state of the line ahead to train/engine drivers. The driver interprets the signal s… …
19Token (railway signalling) — A token being offered by a signalman on the Keighley and Worth Valley Railway …
20Royal Aircraft Factory S.E.5 — Role Single seat fighter Manufacturer various (see text) Designer …
