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  • #1814497
    tomdenne
    tomdenne
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    Joined: 29 Oct 2008
    Location: 58 La Nièvre
    Total posts: 4459

    Does anyone know why the French electrical symbol for volts is U, especially when they habitually call it tension, as we sometimes do. It’s bad enough that amps have the symbol I but because that stands for intensité there is a certain strange logic there. Watts have the symbol P for puissance, so that is sort of understandable too. But U??

    Have searched for an answer but the best is a suggestion that it might come from the German for difference, unterschied but that really does sound like a bit of a stretch. The most bizarre thing is that watts, volts and amps are all units fully understood in France.


    Tom

    #1814502
    robertarthur
    robertarthur
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    Joined: 29 Nov 2010
    Location: Nièvre (58)
    Total posts: 2157

    Because dedicated followers of fashion as they are the French are not afraid of products from the other side of the river Rhine (BMW, Audi). See also this postage stamp.


    RA

    #1814511
    tomdenne
    tomdenne
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    Location: 58 La Nièvre
    Total posts: 4459

    Thanks for the explanation RA but I’m still puzzled. BW Wechselstrom 110V 220V zu DC 12V 6A 72W is from an advertisement today in Amazon.de. Why use two different symbols for volts?


    Tom

    #1814513
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    Chanceux
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    Joined: 17 Mar 2010
    Location: Picardie
    Total posts: 13130

    You learn something every day!

    I must have read loads of electrical calculations and had never picked up on it, certainly the calculations I had to submit to ERDF for the voltage drops, power ratings and foisonnement of my colonne collectif I used SI units without a second thought.

    I am shocked that SI units are not used, what is the point of standardisation and harmonisation?


    #1814516
    loopski
    loopski
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    https://goo.gl/images/m3yQgX


    I would lie on top of the stairs and smell the cigar smoke of Castro.

    #1814518
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    fittersmate
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    Joined: 08 Jun 2009
    Location: Brittany France dept 56
    Total posts: 1624

    There is no S.I. unit with the symbol “U”

    Possibly they use “U” instead of V to avoid confusion with “v” standing  for velocity?      ie   –     v = meters/sec in SI units

    Strangely Guiseppe Volta was close to and admired by Napoleon Bonaparte, so you would think the french would have no problem with using the synbol V for voltage or electrical tension.


    • This reply was modified 05 Dec 2017 00:19 by  fittersmate.
    #1814525
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    mikej
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    Joined: 21 Jun 2011
    Location: Dordogne sometimes and Kent the rest
    Total posts: 5287

    Strange and probably nothing to do with it, but in old English V was used instead of U as in Plvmsted, this can be seen on the pre victorian fire station in Plumsted.

    Mike


    WFIPFLL

    • This reply was modified 05 Dec 2017 02:00 by  mikej.
    • This reply was modified 05 Dec 2017 02:03 by  mikej.
    • This reply was modified 05 Dec 2017 02:04 by  mikej.
    #1814534
    tomdenne
    tomdenne
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    Joined: 29 Oct 2008
    Location: 58 La Nièvre
    Total posts: 4459

    Strangely Guiseppe Volta was close to and admired by Napoleon Bonaparte, so you would think the french would have no problem with using the synbol V for voltage or electrical tension.

    That’s interesting. In one French book about electricity the word voltage is mentioned but it is dismissed as an anglicism. However, in English we also talk about high tension power lines or HT cables for spark plugs. Apparently voltage and V are now now becoming more widely used in France.


    Tom

    #1814537
    AnOther
    AnOther
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    Joined: 11 Jan 2008
    Location: W of Cahors (46)
    Total posts: 9455

    In France tension is also blood pressure of course !


    #1814544
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    fittersmate
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    Joined: 08 Jun 2009
    Location: Brittany France dept 56
    Total posts: 1624

    Sorry – got Volta’s name wrong – Alessandro Guiseppe Volta.


    #1814558
    robertarthur
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    Joined: 29 Nov 2010
    Location: Nièvre (58)
    Total posts: 2157

    With such an urgent question it would be a pity if Tomdenne would have to spend his Xmas days in a state of cultural and linguistic confusion in la France profonde. What about the Romans who used te word “urgere”: to push. Isn’t that what a higher voltage does, push electrons to the lower side of their playing field? It’s too late to ask Georg Ohm himself, who probably got his fair share of Latin grammar at the Erlangen Gymnasium, if this is the origin of U, short for urgere. A plausible explanation. I stand to be corrected.


    RA

    #1814561
    chris-le-bricoleur
    chris-le-bricoleur
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    Joined: 03 Dec 2010
    Location: NL and 52
    Total posts: 1381

    Just thought a little bit about this question.

    The basic equation is, in words:
    POWER = TENSION x CURRENT

    Now you can express this with the symbols agreed for these terms
    power = P,   tension = U,    current  = I
    and you get:
    P = U x I
    Or you can express the same equations using the SI* units which are internationally agreed for the three terms (power is expressed in Watts or HP, tension in Volts, current in Ampères) and you get:
    W = V x A
    * SI = International System of Units 

    The simple explanation is thus:
    The French use the symbols agreed for the terms, others the SI units.

    As an engineer I would write the equation as:
    P[W] = U[V] x I[A]
    or on laymen’s terms:
    Power P [expressed in Watts] is the product of Tension U [expressed in Volt] and the current I [expressed in Ampère].

    This is the result of my early-morning-thoughts. Please, correct me if I’m wrong.


    Christian - bricoleur par passion, pas par necessité http://www.klussen-in-frankrijk.eu/

    #1814567
    chris-le-bricoleur
    chris-le-bricoleur
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    Joined: 03 Dec 2010
    Location: NL and 52
    Total posts: 1381

    Just another thought.

    It’s like the difference between
    (à la Française):     Vous avez roulé à quelle vitesse? and
    (the english way):  How many mph did you drive?


    Christian - bricoleur par passion, pas par necessité http://www.klussen-in-frankrijk.eu/

    #1814568
    loopski
    loopski
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    Joined: 23 Jan 2013
    Location: deux sèvres
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    https://faq.tweakers.net/cme/wetvanohm.html


    I would lie on top of the stairs and smell the cigar smoke of Castro.

    #1814574
    loopski
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    Good explanation Chris neatly emphasising the distinction between a Symbol and a Unit.
    Viz: Formelzeichen und Einheit.
    .
    https://www.lernhelfer.de/schuelerlexikon/physik/artikel/elektrische-spannung


    I would lie on top of the stairs and smell the cigar smoke of Castro.

French Electrical & Other Building Issues
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