Take a look.
http://www.cis.rit.edu/htbooks/mri/
Hardware is near the bottom. Generally more info than any sane individual
would want <gr>
A little lighter stuff is at:
http://www.howstuffworks.com/mri.htm
----- Original Message -----
From: "tongaloa" <tongaloa@alltel.net>
To: <tentec@contesting.com>
Sent: Thursday, December 11, 2003 21:36
Subject: Re: [TenTec] Induction Field [WAS - PS grounding]
> Pete-
>
> OK
> But I still don't understand how enough EMF can be generated to cause
> problems.
>
> I'm probably confused by the ratings they use on MRI machines.
> When I'm in the MRI machine and it's a 0.5T field (according to the
> operator) does he really mean 0.5T/s or does he mean the maximum field
> strength is 0.5T
> which at MRI operating frequencies is lots more than the 0.02T field
> strength at a meter
> from a pretty good sized, real, lightning bolt.
>
> If the lightning bolt takes 10 microseconds to go from 'small' to 'full'
> current then
> it's roughly 200T/s which would produce a LOT more EMF than a 0.5T/s
MRI...
> I don't know MRI operating frequency but at 500kHz it would be roughly
> 500T/s
> if the 0.5T (operator number) is the max. (I think 500kHz is abotu
> right??? Any MRI
> ops out there?)
>
> I didn't croak in the MRI machine and I was there for an hour ;-)
>
> 73,
> -Bob
>
>
>
>
> ac5e@comcast.net wrote:
>
> >Bob, an induction field is an induced current, or voltage, resulting from
current flow. Lotsa current equals lotsa induction field. Which, according
to the local street preacher, is often followed by checking out a harp and
wings.
> >
> >The human body is essentially a high resistance one turn inductor. In lab
testing during the 1950's more than 5 Kv at 10 A was measured in a cadaver
near a lab lightning stroke. And lab lightning is a very mild cousin to the
wild lightning generated in a thunderstorm. Do not put your unshielded self
or anything you value near anything that will attract the wild stuff.
> >
> >And I forgot who asked, but yes, your rotor cables need to be lightning
arrestored, grounded, and anything else that can be done to keep the big
sparks away.
> >
> >73 Pete Allen AC5E
> >
> >
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> >TenTec@contesting.com
> >http://lists.contesting.com/mailman/listinfo/tentec
> >
> >
> >
>
>
>
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