Thanks Jim. You're correct in every respect of course, and the
cautions you've given are essentially the same as what I had already
established for myself.

However, I think you'd be a little surprised (as I was) to find that
there's a lack of specific guidance in the industry on these
situations. At least based on my research to date.

I've found lots of anecdotal tales of arcing and sparking in these
situations, but thus far nothing involving personal injury or worse.
Thus far, the worst consequence I've heard of has been a plant trip.
Even that is a million dollar or so event though.

I'm not asking anyone to provide input on safety procedures; just
trying to pick up some ideas on what theory predicts. Maybe I should
pose a purely theoretical puzzler unrelated to safety, scaffolding, or
power plants.

There's a loop in a square configuration, 3 meters on a side, adjacent
to a long conductor carrying 1400 amps AC at 60 Hz. The side nearest
the conductor is 1 meter from it. The loop is made of aluminum tubing
75cm in diameter.

What current is induced in the loop when it is closed? What voltage
exists across the gap if a gap is cut into the loop?

73--Nick, WA5BDU

BTW: 1,400 is 5% of 28,000

- I've worked on some of those really big battery banks too.



Jim Higgins wrote:
On 23 Aug 2006 11:32:31 -0700, wrote:

I'm a long-time reader of this NG and so realize that there is a lot
of knowledge of EM principles on tap here. I'm pondering a non-ham
issue from my workplace (a power plant) and could use a little
education or peer checking of my ideas.


I think it's good that you're pondering, but I think any consideration
of changes in the established work methods should be avoided unless
they are discussed with and approved by personnel charged with
workplace safety. The power industry wasn't born yesterday and if
people aren't dying or being injured using current practices I think
it ill advised to make changes on your own based on your own
conjecture and most especially based on conjecture from others without
experience in the same environment.

Working around large lead acid batteries for 30 years - and I'm
talking stuff that will easily deliver 10,000 DC amperes to a short,
I've seen people who thought they knew better than the those who
established procedures for them to follow very severely injured.

Not the same thing at all as 28,000 AC amperes, but if you have to ask
first then you shouldn't be making changes. Just my opinion. No
offense intended.

On 25 Aug 2006 08:53:42 -0700, wrote:

What voltage exists across the gap if a gap is cut into the loop?

Hi Nick,

About enough to light a small flash light bulb, or if rectified, an
LED.

73's
Richard Clark, KB7QHC

Hi Nick

Are actually able to get anywhere close to a 1,000 megawatt 3 phase power
line without strict supervision from the management of that station??
My limited experience with stations associated with that voltage and
curent indicate that there are really well qualified electrical engineers
close by at all times. They have always seemed capable of understanding
inductive coupling and have maintained close supervision of all personel
near the plant.
Where is this location?

Jerry


wrote in message
ups.com...
Thanks Jim. You're correct in every respect of course, and the
cautions you've given are essentially the same as what I had already
established for myself.

However, I think you'd be a little surprised (as I was) to find that
there's a lack of specific guidance in the industry on these
situations. At least based on my research to date.

I've found lots of anecdotal tales of arcing and sparking in these
situations, but thus far nothing involving personal injury or worse.
Thus far, the worst consequence I've heard of has been a plant trip.
Even that is a million dollar or so event though.

I'm not asking anyone to provide input on safety procedures; just
trying to pick up some ideas on what theory predicts. Maybe I should
pose a purely theoretical puzzler unrelated to safety, scaffolding, or
power plants.

There's a loop in a square configuration, 3 meters on a side, adjacent
to a long conductor carrying 1400 amps AC at 60 Hz. The side nearest
the conductor is 1 meter from it. The loop is made of aluminum tubing
75cm in diameter.

What current is induced in the loop when it is closed? What voltage
exists across the gap if a gap is cut into the loop?

73--Nick, WA5BDU

BTW: 1,400 is 5% of 28,000

- I've worked on some of those really big battery banks too.



Jim Higgins wrote:
On 23 Aug 2006 11:32:31 -0700, wrote:

I'm a long-time reader of this NG and so realize that there is a lot
of knowledge of EM principles on tap here. I'm pondering a non-ham
issue from my workplace (a power plant) and could use a little
education or peer checking of my ideas.


I think it's good that you're pondering, but I think any consideration
of changes in the established work methods should be avoided unless
they are discussed with and approved by personnel charged with
workplace safety. The power industry wasn't born yesterday and if
people aren't dying or being injured using current practices I think
it ill advised to make changes on your own based on your own
conjecture and most especially based on conjecture from others without
experience in the same environment.

Working around large lead acid batteries for 30 years - and I'm
talking stuff that will easily deliver 10,000 DC amperes to a short,
I've seen people who thought they knew better than the those who
established procedures for them to follow very severely injured.

Not the same thing at all as 28,000 AC amperes, but if you have to ask
first then you shouldn't be making changes. Just my opinion. No
offense intended.