Twirt at Hutchtel on sat 30 jun 07
Lily & all,
When I lived in Wyoming, a guy was firing his small skutt in his trailer
park. the line capacity was so marginal that he frequently make 06.
Probably 14 years ago, I posted an experience in Illinois. I was having
trouble getting to temp and neighbors mentioned 'brownouts'. Turned out the
connection of my house to the line at the pole was corroded and exacerbated
by the load the kiln put on it. Every time I fired, it made it worse.
electric company finally came out, cleaned the lines, put on their
conductive goop and everything was fine. (Most transmission lines are
aluminum and subject to oxidation.
Tom Wirt
 Original Message 
From: "Lili Krakowski"
To:
Sent: Saturday, June 30, 2007 10:03 AM
Subject: Slow kilns, Voltage drops, and tell us please
>A few days ago someone had a problem with a kiln that did not fire
>properly.
> The bar in the kiln sitter HAD worked properly for an 06 firing but not
> for
> a c.6. Several questions were asked in response to the original query,
> several solutions offered, but we have not heard back. When people ask
> and
> others answer it really would be nice if we all were told what solution
> worked....This not only mattters for NOW but also for the Archives.
>
> Now what I wrote in was that a voltage drop might cause the delay/failue.
> As I am not savvy enought toe xplain the resluts I wrote an electrical
> engineer, a wonderful young friend, who kindly replies (with permission to
> quote). So here, from Steve Longway is an explanation you well might
> file
> away.
>
> " ... [V]oltage drop does have a dramatic effect on the heating ability of
> a
> resistive heating element (not exactly exponential, but almost).
> ...[H]ere
> is a simple example...
>
> We'll say for example that you have a 6000 Watt Kiln that operates at 120
> Volts. With a little manipulation of Ohm's law, you can prove that:
>
> Power(watts)=(Volts Squared)/Resistance
>
> With a little algebra, R = V(squared)/W, so R=(120*120)/6000 = 2.4 ohms
> of
> resistance.
>
> So now lets say it's 100 degrees out, and everyone on the block has there
> air conditioners on. The distribution system will start to feel the
> burden,
> and the voltage at your outlet (118120V normally) has now dropped down to
> 110V. It could potentially drop quite a bit more, but we'll say you are
> close to a substation, not at the end of the line, and you are only seeing
> a
> little bit of this.
>
> Sooooo..... Using P=VSquared/R, and knowing that your resistance will not
> change, Lets see how many Watts our kiln is now putting out...
>
> P= (110V*110V)/2.4 = 5041.7 Watts. That's right, your monstrous Kiln just
> lost 1/6 of it's heating ability.
>
> So, suffice it to say, keeping voltage drop to a minimum is critical for
> resistive heating loads (like an electric oven or kiln)."
>
> That is what that is about...or why I honestly truly think that checking
> the
> voltage is a good idea befoe one starts tearing the kiln apart.
>
>
>
>
>
>
>
>
>
>
>
>
> Lili Krakowski
> Be of good courage
>
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> Send postings to clayart@lsv.ceramics.org
>
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>
Lili Krakowski on sat 30 jun 07
A few days ago someone had a problem with a kiln that did not fire properly.
The bar in the kiln sitter HAD worked properly for an 06 firing but not for
a c.6. Several questions were asked in response to the original query,
several solutions offered, but we have not heard back. When people ask and
others answer it really would be nice if we all were told what solution
worked....This not only mattters for NOW but also for the Archives.
Now what I wrote in was that a voltage drop might cause the delay/failue.
As I am not savvy enought toe xplain the resluts I wrote an electrical
engineer, a wonderful young friend, who kindly replies (with permission to
quote). So here, from Steve Longway is an explanation you well might file
away.
" ... [V]oltage drop does have a dramatic effect on the heating ability of a
resistive heating element (not exactly exponential, but almost). ...[H]ere
is a simple example...
We'll say for example that you have a 6000 Watt Kiln that operates at 120
Volts. With a little manipulation of Ohm's law, you can prove that:
Power(watts)=(Volts Squared)/Resistance
With a little algebra, R = V(squared)/W, so R=(120*120)/6000 = 2.4 ohms of
resistance.
So now lets say it's 100 degrees out, and everyone on the block has there
air conditioners on. The distribution system will start to feel the burden,
and the voltage at your outlet (118120V normally) has now dropped down to
110V. It could potentially drop quite a bit more, but we'll say you are
close to a substation, not at the end of the line, and you are only seeing a
little bit of this.
Sooooo..... Using P=VSquared/R, and knowing that your resistance will not
change, Lets see how many Watts our kiln is now putting out...
P= (110V*110V)/2.4 = 5041.7 Watts. That's right, your monstrous Kiln just
lost 1/6 of it's heating ability.
So, suffice it to say, keeping voltage drop to a minimum is critical for
resistive heating loads (like an electric oven or kiln)."
That is what that is about...or why I honestly truly think that checking the
voltage is a good idea befoe one starts tearing the kiln apart.
Lili Krakowski
Be of good courage
Arnold Howard on mon 2 jul 07
From: "Twirt at Hutchtel"
Every time I fired, it made it worse.
> electric company finally came out, cleaned the lines, put
> on their
> conductive goop and everything was fine. (Most
> transmission lines are
> aluminum and subject to oxidation.
This same problem can occur inside a kiln's switch box.
Loose element connectors can slow down the firing. They will
appear discolored.
A loose grounding wire can cause digital controllers to
malfunction. A couple of months ago, a technician came to my
house to install AT&T digital cable. He spent the entire day
trying to figure out why it kept shutting off. A different
technician came out the next day and discovered that a wall
outlet had a loose grounding wire.
A loose wire clamp on a grounding rod can cause problems
too. The grounding rod goes into the earth and is part of
the main electrical system for the building.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
Arnold Howard on mon 2 jul 07
From: "Lili Krakowski"
> P= (110V*110V)/2.4 = 5041.7 Watts. That's right, your
> monstrous Kiln just
> lost 1/6 of it's heating ability.
Lili, thanks for posting the excellent article on voltage
drop.
Here is the formula I use to calculate power loss due to
voltage drop:
low voltage (squared)

correct voltage (squared)
110 squared

120 squared
110 x 110 = 12,100
120 x 120 = 14,400
12,100 divided by 14,400 = .84
100  84 = 16 percent loss of power
Using this formula, you will find that firing a 240 volt
kiln on 208 volts reduces power by 25%. Low voltage has the
same effect as firing with worn out elements.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
 
