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 > Electricity and electric and magnetic fields (EMFs)

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Harvard

51.6N 114.7W

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Posted: 05/17/19 11:24am Link  |  Quote  |  Print  |  Notify Moderator

road-runner wrote:

I once visited somebody whose back deck was a few hundred feet from some high voltage lines. On the deck he held up a fluorescent tube, and it lit up (not at full brightness).


So, it is pretty clear there was a voltage present, therefore the question, "was it induced, or what?"
I NOW think it was voltage from the Electric Field. In the past I would have guessed induction...

myredracer

Langley B.C.

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Posted: 05/17/19 11:26am Link  |  Quote  |  Print  |  Notify Moderator

Harvard wrote:

Re: "Look at the insulators"

Where is the 3rd phase?
That would be a lower voltage "local" single phase transmission line, one hot and one neutral. Maybe 60 KV? The hot and neutral cancel out the EMF. Three phase 500 KV transmission lines (usually 3-conductor delta configuration, not wye) are more efficient and transit more power using comparatively smaller size aluminum conductors and less aluminum per foot. The 3 phases (180 degrees apart) also cancel out the EMF. Below is what a 500 KV transmission line looks like and are much taller.

Local residential/rural high voltage lines on streets (in Canada at least) are 12 or 25 KV and the high voltage primary and low voltage secondary (120/240) share a common neutral which is why you see only one insulator on the poles like in diagram below.

In the last diagram, which wire is a neutral and what is the voltage?

[image][image][image]

* This post was edited 05/17/19 11:36am by myredracer *


I hate CAPTCHA. CAPTCHA sux. CAPTCHA is evil. CAPTCHA needs fixing.

Gil, Deb & Dougal the Springer Spaniel
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MEXICOWANDERER

las peñas, michoacan, mexico

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Posted: 05/17/19 11:50am Link  |  Quote  |  Print  |  Notify Moderator

Look for the klystron Thyristors, at the end terminals. Both conductors you see are of similar orientation. Opposition polarity is hidden. Can you find it? [emoticon]

Harvard

51.6N 114.7W

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Posted: 05/17/19 12:43pm Link  |  Quote  |  Print  |  Notify Moderator

JaxDad wrote:

A farmer near here got pinched by the nice folks at our electrical utility a while back.

He had a very well lit barn and storage / shop building for his side business.

Then we had a power failure.......

When the linesmen went past they thought it odd that his outbuildings were well lit but not his house or anything else.

Then it dawned on them, there was a 500 KV transmission corridor running across his pasture.

When they discovered he ha buried a huge loop of wire zig-zagging back & forth beneath the transmission lines they handed hm a huge bill based on what they 'estimated' his consumption had been.

So much for 'free' electricity.......


This is a great story to tell because it is a head scratcher. So was it via inductance to the Magnetic Field or capacitance to the Electric Field. Unquestionably it was the latter and here is why:

The power line was severed downstream of the farm so there would be no current flowing (so no Magnetic Field) BUT the upstream portion over the farm was still powered up. So we have a full blown Electric Field over the farmers "capacitance plate" in the field.

A single conductor from the capacitance plate to the primary of his transformer and the bottom of the primary to a ground rod in Earth.

[emoticon] [emoticon] [emoticon]

On second thought, the towers were on line but the local distribution was down So, it could have been inductance to the Magnetic Field. My bad.

* This post was edited 05/17/19 01:56pm by Harvard *

Harvard

51.6N 114.7W

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Posted: 05/17/19 01:08pm Link  |  Quote  |  Print  |  Notify Moderator

"In the last diagram, which wire is a neutral and what is the voltage?"

I'll byte:

The neutral is the "stringer" and the voltage to Earth is 0 VAC at the Neutral Earth bonding point.
The bonding neutral (stringer) to Earth is in the breaker panel.

Note: "stringer" being the bare conductor cable physically supporting the L1 and L2 conductors.

* This post was edited 05/17/19 01:22pm by Harvard *

MEXICOWANDERER

las peñas, michoacan, mexico

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Posted: 05/17/19 03:40pm Link  |  Quote  |  Print  |  Notify Moderator

It's the Path 4, West Coast intertie line. Washington state to Reseda CA. 3.5 gigawatts capacity. Direct current system. Not A.C.

It's 1 megavolts 1,000,000 volts direct current. The 10 meter distance, length of the insulators, is a clue.

The two wires are the same polarity.

in a ditch adjacent to the towers is the negative pathway. It is filled with conductive media. I was invited to a field survey in Ely Nevada that discussed basic soil composition and conductance to minimize earth eddy currents. Eastern Nevada was chosen over the alternatives because of that reason. I was a guest of Siemens.

Software controlled conversion and reversion of DC. Components are giga size with appropriate cooling air temperatures, moisture and contaminate containment.

An interesting study. The science behind it is in another dimension. This is PhD territory beyond my capabilities when I attended and now outside my area of interest. Power generation and storage is quite enough for me these days [emoticon]

Software controlled rectification using ultra low forward voltage drop interests me. As does artificial EMP and solar EMP. If alternator rectification involved .002 vf you cannot imagine the advantages. And it implies direct interface with camping and RV'ing. [emoticon]

Harvard

51.6N 114.7W

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Posted: 05/17/19 04:05pm Link  |  Quote  |  Print  |  Notify Moderator

Mex!!!! Very interesting, thanks for sharing. I will be thinking about DC transmission advantages for a very long time.

road-runner

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Posted: 05/17/19 06:18pm Link  |  Quote  |  Print  |  Notify Moderator

I had totally forgotten about the DC intertie. There's a wikipedia article, and sure enough, it has a picture of a tower with two big insulators.
https://en.wikipedia.org/wiki/Pacific_DC_Intertie


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Harvard

51.6N 114.7W

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Posted: 05/17/19 07:03pm Link  |  Quote  |  Print  |  Notify Moderator

Neat stuff, had no idea DC transmission has been around since the 1970s..
So I do have some knowledge of the Magnetic Field around a DC circuit.
BUT, nothing about a DC Electric Field, or so I thought....
Then Dr Google says this:
"DC Electric Field: DC Electric Fields, can be referred to as an Electrostatic Charge present on an object"
Now that I understand.

MEXICOWANDERER

las peñas, michoacan, mexico

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Posted: 05/17/19 07:16pm Link  |  Quote  |  Print  |  Notify Moderator

The monitoring and control rooms are basically insulated to prevent electrostatic build up. With av pacemaker today I wouldn't get within a mile of the place.

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