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Website Math Error?

Discussion in 'Tesla, Inc.' started by jehan2256, Oct 13, 2017.

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  1. jehan2256

    jehan2256 New Member

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    Oct 13, 2017
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    I noticed something peculiar on Tesla's website today...

    Capture.JPG

    It says that if you charge at 24A on a 3-phase circuit, you'll get 16.5kW of power.

    If we do some math...

    16500W/24A = 687.5V

    I don't know of any household circuit with such a high voltage.

    What's I noticed, however, is that 687.5 is approximately 3 times 230, which is the standard household voltage (in most countries).

    So it seems like whoever wrote this information was under the impression that 3-phase power gives you 3 times the voltage of single phase, whereas it actually gives you the square root of 3 (1.73) times the voltage.

    So, am I missing something, or did Tesla get their figures wrong?
     
  2. MasterT

    MasterT Member

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    I'm not really an expert but I think you might be confusing calculations with line to line voltage (which uses square root of 3) with line to neutral voltage (which uses 3 times the voltage)
     
  3. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Well-Known Member

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    It would be _400V_ 3 phase. Each phase is 400/3^0.5 = 230.94.

    400 x 24 * 3^0.5 = 16.627.
    (= 400/3^0.5/phase * 24A * 3 phases)
     
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  4. McRat

    McRat Active Member

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    Yes, it's why 3ph kicks arse. There are 3 hots. Each one pulls amps.

    If EVs in the USA would accept the common 3-ph at a mear 24a (30a breaker):
    208vac 3ph = 3 lines x 24 amps x 120v = 8.6 kW
    480vac 3ph = 3 lines x 24 amps x 277v = 20 kW

    This can be done on a dedicated short run of 10 awg THWN-2 with 30a breaker. Cheap setup
     
  5. jehan2256

    jehan2256 New Member

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    Thanks guys, that cleared up some confusion.
     

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