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Thread: 60 Hz vs. 400 Hz.

  1. #1
    Join Date
    Jan 2008
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    60 Hz vs. 400 Hz.

    What would be the effect of plugging a laptop power supply (rated at 100-240 V, 50/60 Hz, 19.5 VDC output) in an 115 V, 400 Hz outlet?
    This question relates to airline pilots plugging their laptops into aircraft power receptacles... Thanks,

  2. #2
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    It would depend on the Laptop Power Supply technology being used. If it is Switch Mode Power Supply it may work because a SMPW converts the AC line directly to DC. The problem could/would be the AC line filters installed from L-G, L-N, and N-G would be designed for 60 Hz and could burn up at the higher frequencies.

    If it is a linear power supply (using a step-down transformer) it would not likely work at all, or the output voltage would be way to low.

  3. #3
    Join Date
    Mar 2008
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    17

    60Hz vs 400Hz

    Quote Originally Posted by dereckbc
    It would depend on the Laptop Power Supply technology being used. If it is Switch Mode Power Supply it may work because a SMPW converts the AC line directly to DC. The problem could/would be the AC line filters installed from L-G, L-N, and N-G would be designed for 60 Hz and could burn up at the higher frequencies.

    If it is a linear power supply (using a step-down transformer) it would not likely work at all, or the output voltage would be way to low.

    I guess >> .. ..

    Shwaz

  4. #4
    Join Date
    Mar 2008
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    400Hz

    As a flight attendant, I've charged my cell phone and laptop many a time using the onboard 400Hz power outlet. In flight I've never had a problem, but once in a great while I'd get a power surge when they switch from ground power to the APU or vice versa, most notibly on the B767, although I word of mouth says the 737 isn't immune to these either. Get a small surge protector to protect your investment.

  5. #5
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    Mar 2008
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    You can charge your laptop/cell phone on all of UAL's fleet. I just wouldn't recomend it when you're on the ground, occasionally there is a surge.

  6. #6
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    Nov 2007
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    why do aircraft run at 400hz?

  7. #7
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    Transformers are smaller if I remember correctly. Im sure thats not the only reason.

  8. #8
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    Mar 2008
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    Pennsylvania
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    Cool Transformer size and weight is the answer.

    Why do airplanes run on 400 hz.

    Simple, it is a matter of weight. Transformers are affected by frequency, and if you design transformers for a living, you know that the higher the frequency the less iron you need due to the basic physics (the EMF generated in a coil is proportional to both to flux and frequency- hence higher frequencies require less flux and laes iron.) 400 Hz transformers, and lamp ballasts, generators motors are all lighter and smaller then comparable 60 Hz units.

    Also turbines engines run faster then 3600 RPM of a two pole 60 Hz generator, and the gearing and constant-speed-drive unit used in earlier jet aircraft is simplier and lighter. is simplier. [Most newer aircraft use wild frequency generators aand convert the resulting current to a fixed 400 Hertz.

    Note this principle applies for 50 and 60. Since the europeon systems use 380 volts instand of 480, motors can be dual-rated. sincre the current is the same, the horsepower, and speed at 50 hz is 5/6 of the 60 Hz rating.

  9. #9
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    here's your sign!

    the mystery of 400 hz explained... http://www.aerospaceweb.org/question...cs/q0219.shtml






    weight reduction
    $$$$$
    ambidextrious wirenutter
    All quoted sections are from NEC 2008 unless otherwise stated

  10. #10
    Join Date
    Jun 2004
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    Doubt any receptical (like a 5-15) on an airplane that you can "PLUG" a consumer electronic device into would be 400hz.... But regenerated at 50-60 using an on-board rotary or electronic frequncy convertor.
    http://www.avionicinstruments.com/p_...ers_specs.html

    Anyway - my understanding was that many radar systems are ineffeciant at lower freq's and needed much higher power internal to the equipment than available from DC or lower freq AC - could be wrong???
    Electric heretic
    It's always gonna be in the last place you look....

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