Page 1 of 15 1234511 ... LastLast
Results 1 to 10 of 148

Thread: EMF Radiation

  1. #1
    Roadster #108 and SSL #61
    Join Date
    Feb 2009
    Location
    Santa Barbara, CA
    Posts
    175

    EMF Radiation

    I've seen in several blogs now where a commenter has stated that the Roadster is like "strapping a bag of cell phones to your head", in terms of the EMF radiation. So I picked up an EMF detector, sensitive in the 30-300Hz range (serendipitously equivalent to 1800 - 18000RPM), and took my Roadster for a spin.

    For calibration, the meter shows around 100 milligauss when placed next to my iPhone on a call, in the position my head would be.

    In the Roadster, I found that the only place in the cabin with noticeable EMF levels is just above the headrest; the reading peaked there at 50 milligauss (half the strength of a cell phone) for a couple seconds during peak acceleration. While cruising, the EMF reading there was around 3-4 milligauss, and dropped to imperceptible levels throughout the rest of the cabin.

    In other words, the kinetic energy of the Roadster is a far greater concern than the electromagnetic energy. Thought some of you might like to know!

    -Ben

  2. #2
    mod squad TEG's Avatar
    Join Date
    Aug 2006
    Location
    Silicon Valley
    Posts
    15,211
    Thanks for some real data. I figured those reports were trumped up sensationalism, but I had no way to disprove it myself.

  3. #3
    Senior Member WarpedOne's Avatar
    Join Date
    Aug 2006
    Location
    Slovenia, Europe
    Posts
    1,317
    This post should be made sticky so we have it at hand when someone somewhere starts to spread this FUD again.

    Thank you!
    I believe in Tesla as a concept, a brand, and a suite of products. No matter who conceived, started, runs, or maintains, I hope it ultimately prevails and lasts.
    -- TEG


  4. #4
    2008 Roadster #181 DaveD's Avatar
    Join Date
    Aug 2007
    Location
    Redmond, WA
    Posts
    412
    I wonder what the measurement would be near a Bluetooth headset that I see so many people wearing around nowadays.

  5. #5
    ERIC VFX vfx's Avatar
    Join Date
    Aug 2006
    Location
    CA CA
    Posts
    14,796
    I wonder what other motorized devices get placed near the body.

  6. #6
    Roadster #108 and SSL #61
    Join Date
    Feb 2009
    Location
    Santa Barbara, CA
    Posts
    175
    Quote Originally Posted by DaveD View Post
    I wonder what the measurement would be near a Bluetooth headset that I see so many people wearing around nowadays.
    Zero. (Unmeasurable.) At least a thousand times less than the cell phone itself. Remember, the cell phone has to broadcast its signal a few kilometers; the bluetooth no more than 10 meters, and broadcasting power increases with the square of distance. My detector wasn't able to pick up any trace of EMF from my Jawbone bluetooth headset.

  7. #7
    Roadster #108 and SSL #61
    Join Date
    Feb 2009
    Location
    Santa Barbara, CA
    Posts
    175
    Quote Originally Posted by vfx View Post
    I wonder what other motorized devices get placed near the body.
    Probably not what you're thinking of, but hair dryers put out at least as much EMF as cell phones.

    Those other gadgets -- well, no risk, no reward.

  8. #8
    Senior Member dpeilow's Avatar
    Join Date
    May 2008
    Location
    Winchester, UK
    Posts
    7,653
    Quote Originally Posted by WarpedOne View Post
    This post should be made sticky so we have it at hand when someone somewhere starts to spread this FUD again.

    Thank you!
    Good idea. Done.

  9. #9
    Senior Member WarpedOne's Avatar
    Join Date
    Aug 2006
    Location
    Slovenia, Europe
    Posts
    1,317
    It looks to me this case was closed a little bit too fast.

    According to Wikipeda, variable-frequency drives have something called Carrier Switching Frequency (CSF), a frequency of the current going through the stator windings which is completely different from the frequency of rotating magnetic field in this same stator. This one varies from 0 to 430Hz (at 13.000 rpm of a 4-pole motor).

    30-300Hz EMF detector is as such completly inadequate for the job at hand. CSFs are usually in tens of kHz so one should get a detector with suitable range and repeat the measurements.

    Not that I'm afaird of EMF, I would just like to have correct results :|
    I believe in Tesla as a concept, a brand, and a suite of products. No matter who conceived, started, runs, or maintains, I hope it ultimately prevails and lasts.
    -- TEG


  10. #10
    Roadster #619
    Join Date
    Mar 2008
    Posts
    110
    A couple of thoughts:
    the EMF meter you're using won't be able to detect the (primary) emissions from the car due to its limited bandwidth (300Hz). Main emission frequency will likely be in the >10kHz range due to the PEM module's primary switching frequency (which should be many times higher than the motor's RPM).

    Bluetooth runs at 2.4GHz and ~0dBm (1mW). You could not detect it with a 300Hz detector.

    Cellular runs at ~900MHz/1.8GHz at +24dBm max, but typically around +18dBm -- less than 100mW.

    If a San Diego-based roadster owner wants to stop by Sorrento Valley, I'll volunteer the use of a good Spectrum analyzer to sniff around the car.

    Dan.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. EMF Radiation and the Roadster
    By Ben W in forum Roadster
    Replies: 36
    Last Post: 2012-07-08, 06:41 PM
  2. Torque without Back EMF - Steorn launching new motor technology called E-Orbo.
    By calculator in forum Energy, Environment, and Policy
    Replies: 11
    Last Post: 2010-02-09, 11:29 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •