>As I alluded to, I think we can leave the terrestrial magnetic field out of
>the equation. A length of power cable in free air exhibits the property of
>inductive reactance when there is AC current flow. This XL results when the
>cables own magnetic field expands and collapses about the conductor itself.
>The result is a CEMF which produces current that is out of phase with the
>source current and thus bucks or impedes the flow of current from the
>source. Hence, we have these two current components which are out of phase,
>producing magnetic reaction and mechanical force.
>
** Good point, Jeff. My old "plywood box" 20db amplifier was powered by
AG6K-installed #4 Cu unbundled loose wires in the attic running over the
master bedroom to the electric mains breaker box on the side of the
house. When I was tuning the amplifer up with 50wpn CW dits, my wife
could hear a racket in the attic.
cheerz
>XL on a power cable becomes a real issue as current and cable length
>increase. It's optimal to have a low Z power source for the sake of voltage
>regulation, but also for fast tripping of protective devices. The effect of
>XL is greatly reduced by running the return conductor and ground conductor
>in close proximity to each other.
>
>I'm not saying to do this, but if you were to take a loop of #12 wire say
>50 to 75 feet long, connect the ends to a 20 amp breaker and the ground bus
>in your service panel. Then insert another 20 amp breaker along the wire for
>control. A clampon ammeter set to peak lock is also helpful. When you close
>the remote breaker you should observe movement in the #12 wire. Current will
>peak in the range of 300 to 400 amps and one of the 20 amp breakers should
>clear the fault in a little over a second.
>
>Oh yes, safety glasses, gloves, all cotton clothing, and a C02 fire
>extinguisher are all important when working with high current sources.
>
>Jeff - K1LE - CT ><>
>
> ----- Original Message -----
>From: <MorgusMagnificen@aol.com>
>To: <amps@contesting.com>
>Sent: Friday, February 07, 2003 7:19 PM
>Subject: [Amps] Voodoo Magnetic Fields
>
>
>> Let's calculate (not speculate) on the (Lorenz)force acting on a welding
>> cable laying at ground 0, and one-meter long, carrying a current of
>1000A.,
>> due to its interaction with the geomagnetic field, which we will assume to
>be
>> vertical and of magnitude B=1Gauss (good estimates - just ask your
>friendly
>> geophysicist). Of course, we all recall that the formula for the force on
>a
>> straight conductor in a B-field is:
>>
>> F=BxLxI (MKS units)
>>
>> Using MKS units: F=.00001 x 1 x 1000=.01N.=.0022Lbs=.032Oz.
>> Should really shake up that 4/0! Remember - this is the total force on
>> 1METER of cable, with 1000AMPS flowing.
>>
>> Eric von Valtier K8LV
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
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