Similar experiences here.The contacts are usually just copper or copper
plated with silver.

Many schemes are contrived to save the wear and tear on the contacts. On
larger capacity units there are two sets of contacts, ones that take the arc
and are easy to replace and a second set that can carry big currents, close
last and open first.

Some use vacuum bottled contacts to eliminate arcing and most use an
inductor or resistance not as good) to afford tap changing without ever
breaking the circuit.

Oh, I have dealt with a few pole mounted units for inline use in the rural
long lines to boost it back up a bit.
--------------

"daestrom" wrote in message ...
The few tap-changers I've seen 'up close and personnel' are in
sub-stations, not pole-mounted. The contacts are in oil-bath and
arranged such that they don't open under appreciable current (multiple
contacts, a center-tapped inductor and ingenious mechanism).

--------------
On 4/19/2011 17:28 PM, Jim Wilkins wrote:
Would the contacts be the tungsten (heavy) cylindrical slugs sometimes
found below equipment-laden power poles?

daestrom has a bad day.
You mostly come across as well researched and knowledgeable. From my end I
can tell you are experienced in the field in question and have suspicions we
have crossed paths in real life.

However....

I am surprised you got caught up in that troll. This is not your usual M.O.

This moron changes his nickname almost every post, uses multiple NNTPs and
news browsers to conceal his mental illness that becomes very apparent, very
quickly, to most. He does a little research for the subject at hand in many,
many groups in order to "blend in" with the crowd only to attempt to lead
the sheeple into black-balling a particular person. This technique has
brought many groups to it's knees and made them dormant over many years. We
suspect some past hurt feelings with Usenet in general or a commercial
venture to destroy the Usenet following.

I offer an example of a ghost town group sample:
http://groups.google.ca/groups/searc...Bluto&safe=off

This has been going on since year 2000 with this jerk. He thinks everyone is
the same person.

My apologies for any mental interference this dip**** has caused you or the
group.

-----------------------
"daestrom" wrote in message ...
You're not worth any more of my time...plonk

On Apr 23, 9:53*pm, "Mho" wrote:
daestrom has a bad day.
You mostly come across as well *researched and knowledgeable. From my end I
can tell you are experienced in the field in question and have suspicions we
have crossed paths in real life.

However....

I am surprised you got caught up in that troll. This is not your usual M.O.

This moron changes his nickname almost every post, uses multiple NNTPs and
news browsers to conceal his mental illness that becomes very apparent, very
quickly, to most. He does a little research for the subject at hand in many,
many groups in order to "blend in" with the crowd only to attempt to lead
the sheeple into black-balling a particular person. This technique has
brought many groups to it's knees and made them dormant over many years. We
suspect some past hurt feelings with Usenet in general or a commercial
venture to destroy the Usenet following.

I offer an example of a ghost town group sample:http://groups.google.ca/groups/searc...q=&as_oq=&as_e...

This has been going on since year 2000 with this jerk. He thinks everyone is
the same person.

My apologies for any mental interference this dip**** has caused you or the
group.

-----------------------"daestrom" *wrote in ...

You're not worth any more of my time...plonk

I CHOOSE WHO AND WHAT TO SPEND MY TIME WITH, TOO.....SWISH

With Free Energy extant throughout appliances
there will be no requirement for a HV Grid
anyway.

So long

Old Timers

On Apr 27, 7:40*pm, "Mr A Clarke" wrote:
With Free Energy extant throughout appliances
there will be no requirement for a HV Grid
anyway.

So long

Old Timers

??????????????????

Mr A Clarke wrote:
With Free Energy extant throughout appliances
there will be no requirement for a HV Grid
anyway.

So long

Old Timers

Keep dreaming. That's the closest you will get.

Oh, I dream alright!


"Bob F" wrote in message
...
Mr A Clarke wrote:
With Free Energy extant throughout appliances
there will be no requirement for a HV Grid
anyway.

So long

Old Timers

Keep dreaming. That's the closest you will get.

Dribbling too eh?

"harry" wrote in message
...
On Apr 27, 7:40 pm, "Mr A Clarke" wrote:
With Free Energy extant throughout appliances
there will be no requirement for a HV Grid
anyway.

So long

Old Timers

??????????????????

David Nebenzahl wrote:
Sorry, I don't think you know what you're talking about.

You seem to think that you can "force" or push "voltage" into a line,
by using a higher voltage than what's on the line.

That's not at all what's at work here when one has a photovoltaic
system and an intertie feeding power back into "the grid".

The intertie and the house's power connection are going to be at
pretty much exactly the same voltage. What happens is that the PV
system is connected *in parallel* with the grid; it's dumping more
*current* into the system, not more voltage.

You do understand the difference between current and voltage, don't
you?

"Pretty much the same" is not the same as "the same". The grid may have very low
impedence, so the voltage difference will not be much, but if the voltage you
produce is less than the grid voltage, no current will flow from you to the
grid. The higher your voltage is above the grid voltage (at your house), the
more current will flow into the grid. Kind of like charging a battery - until
you exceed the battery voltage, no current will flow. As the voltage exceeds the
battery voltage the current increases rapidly.

On May 2, 10:54*am, "Bob F" wrote:
David Nebenzahl wrote:
Sorry, I don't think you know what you're talking about.

You seem to think that you can "force" or push "voltage" into a line,
by using a higher voltage than what's on the line.

That's not at all what's at work here when one has a photovoltaic
system and an intertie feeding power back into "the grid".

The intertie and the house's power connection are going to be at
pretty much exactly the same voltage. What happens is that the PV
system is connected *in parallel* with the grid; it's dumping more
*current* into the system, not more voltage.

You do understand the difference between current and voltage, don't
you?

"Pretty much the same" is not the same as "the same". The grid may have very low
impedence, so the voltage difference will not be much, but if the voltage you
produce is less than the grid voltage, no current will flow from you to the
grid. The higher your voltage is above the grid voltage (at your house), the
more current will flow into the grid. Kind of like charging a battery - until
you exceed the battery voltage, no current will flow. As the voltage exceeds the
battery voltage the current increases rapidly.

YES, THAT IS FREAKY THAT WAY, AND WHATS TO KEEP THE GRID FROM
OVERPOWERING THE SWITCHGEAR AND BURNING DOWN HIS SP RIGG AND OR HIS
HOME.

SOME DREAMS ARE NIGHTMARES ;/

TGITM

Wikipedia is not a source of information (by their own definition). Do
not use it for quotes. Now your information is a fourth hand
paraphrasing, lower than a rumour level.

-------
"g" wrote in message ...

On 13/04/2011 17:59, Home Guy wrote:
harry wrote:


What happens to the "say" 1 volt. It is only a local thing because
the utility drops it's output by 5Kw.

I doubt that the regional sub-station is going to do that.

From Wikipedia:
"In an electric power distribution system, voltage regulators may be
installed at a substation or along distribution lines so that all
customers receive steady voltage independent of how much power is drawn
from the line."

Obviously when a local area is supplying power to the grid, power
generation elsewhere will be reduced. And any voltage changes that
results from that will be adjusted with line voltage regulators, if
necessary.




I'm saying that a small-scale PV system is going to raise the local
grid
voltage for the homes connected to the same step-down distribution
transformer.All the linear loads on the local grid will consume the
extra power (probably about 250 to 500 watts per home, including the
house with the PV system on the roof). The extra 250 to 500 watts
will
be divided up between the various AC motors (AC and fridge
compressors,
vent fans) and lights. They don't need the extra volt or two rise on
their power line supply - the motors won't turn any faster and the
lights will just convert those extra watts into heat more than light
output.

How do you get the value 250-500W?

Motors will only increase their energy drain by raising the frequency,
Plus a small loss due to internal resistance in the windings.

As for a resistive load, increasing the voltage from 120 to 125 volt
will result in a power drain increase of about 8.5% or 8.5 W for a 100W
light bulb, assuming 120V is the nominal voltage.

Remember though that the voltage increase on the step-down side of the
transformer due to homeowners PV arrays will be less than 5 volt pretty
much guaranteed. Local codes state a maximum voltage drop (7V in BC)
over the lines to a house, at 80% load of service panel capacity.

Most households have a 200A service panel. A 10kW PV array is well
below
the service panel capacity.

And you cannot just look at the PV array output. You must take into
account the local energy consumers as well. That will reduce the
current
going into the grid, and thus the voltage increase.


The home owner with the PV system will get paid 80 cents / kwh for
the
40-odd amps he's pushing out into the grid, but that energy will be
wasted as it's converted disproportionately into heat - not useful
work
- by the linear loads on the local grid.

You claims are pretty vague, please explain what you mean by wasted.

By the way, there is some "waste" by just using the grid only as well.
Losses everywhere in the grid.


I'm claiming that there won't be a corresponding voltage
down-regulation
at the level of the neighborhood distribution transformer to make the
effort worth while for all stake holders.

What is your definition of worth while? And what do you know about the
utility's voltage regulation policies?

The utilities _have_ to use voltage regulation due to demand changes.

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m II did NOT write:

Wikipedia...

Stop forging my user name, Maynard, Mho, Gimmy Boob, etc.etc... I see
you accidentally left your home phone number and address in another
counterfeit post. Care to see it published? Keep up the postings.

Grow up, Maynard


mike




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Go for it trollboi!
Then get off the Internet. Children are afraid.

You'll always be a POS troll. Only two more years to go to catch up with
your garbage.

How do you like me now?

-------

"m II" wrote in message ...

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1



m II did NOT write:

Wikipedia...

Stop forging my user name, Maynard, Mho, Gimmy Boob, etc.etc... I see
you accidentally left your home phone number and address in another
counterfeit post. Care to see it published? Keep up the postings.

Grow up, Maynard


mike




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