Jonathan Kaplan on fri 18 oct 96
OK Kids! I have a rather vexing electrical element problem.
We reccently rewired all our Paragon TnF 28-3 electric kilns. All work fine
except the last one we did yesterday.
Kiln specs. 240 volts 60 amp breaker kiln pulls around 48 or so. New
controller, all relays work fine, all wiring is fine, in short, everything
is ok, except that the top and bottom set of elements go right to red heat
at about 500 degrees f or so, the controllers works fine, and then when the
kiln gets to 600 degrees, the circuit breaker trips. When I use a
multimmeter to check the resistacen of each element, the readers are under
half of what then should be for new elements.
Questions for the group: did the companysend me wrong elements..eg 220 volt
elements? ANother indicator is that they go so hot they popped right out of
their groves.
We have tested every component of the system, Everyting works except these
elements. My theory is that they are lower voltage elements, hence lower
resistance, heat up way quick and pass the limit of the breaker.
Any help appreciated before I call the company
TIA
Jonathan
Jonathan Kaplan
Ceramic Design Group Ltd./Production Services
PO Box 775112
Steamboat Springs CO 80477
(970) 879-9139*voice and fax
Kenneth D. Westfall on sat 19 oct 96
At 10:26 PM 10/18/96 +0000, you wrote:
>----------------------------Original message----------------------------
>OK Kids! I have a rather vexing electrical element problem.
>
>We reccently rewired all our Paragon TnF 28-3 electric kilns. All work fine
>except the last one we did yesterday.
>Kiln specs. 240 volts 60 amp breaker kiln pulls around 48 or so. New
>controller, all relays work fine, all wiring is fine, in short, everything
>is ok, except that the top and bottom set of elements go right to red heat
>at about 500 degrees f or so, the controllers works fine, and then when the
>kiln gets to 600 degrees, the circuit breaker trips. When I use a
>multimmeter to check the resistacen of each element, the readers are under
>half of what then should be for new elements.
>
>Questions for the group: did the companysend me wrong elements..eg 220 volt
>elements? ANother indicator is that they go so hot they popped right out of
>their groves.
>
>We have tested every component of the system, Everyting works except these
>elements. My theory is that they are lower voltage elements, hence lower
>resistance, heat up way quick and pass the limit of the breaker.
>
>Any help appreciated before I call the company
>
>TIA
>
>Jonathan
>
>
>
>Jonathan Kaplan
>Ceramic Design Group Ltd./Production Services
>PO Box 775112
>Steamboat Springs CO 80477
>
>(970) 879-9139*voice and fax
Dear Jonathan
A good electrician friend of my said that for a resistance load 60 amp
breaker should have no more than a 80% load which is 48 amps. Your breaker
may be getting weak and not able to take in any longer or you could have
been sent 208 volt elements insteaded of 230 volts. I know alot of
schools have had problem with the reverse and there kilns will not reach
temp. If you can a clamp on type amp meter will give you better Idea as to
were the problem is. With it you can check each element and compare it to
each other. Loose or corroded connection can cause high amp draws and
should be check all the way back to and including the breaker. You should
also check to be sure that a conection hasn't grounded its self to the steel
shell.
good luck Kenneth
DON'T GET STUCK IN THE MUDPIES--K & T
Paul Monaghan on sat 19 oct 96
Kenneth D. Westfall wrote:
>
> ----------------------------Original message----------------------------
> At 10:26 PM 10/18/96 +0000, you wrote:
> >----------------------------Original message----------------------------
> >OK Kids! I have a rather vexing electrical element problem.
> >
> >We reccently rewired all our Paragon TnF 28-3 electric kilns. All work fine
> >except the last one we did yesterday.
> >Kiln specs. 240 volts 60 amp breaker kiln pulls around 48 or so. New
> >controller, all relays work fine, all wiring is fine, in short, everything
> >is ok, except that the top and bottom set of elements go right to red heat
> >at about 500 degrees f or so, the controllers works fine, and then when the
> >kiln gets to 600 degrees, the circuit breaker trips. When I use a
> >multimmeter to check the resistacen of each element, the readers are under
> >half of what then should be for new elements.
> >
> >Questions for the group: did the companysend me wrong elements..eg 220 volt
> >elements? ANother indicator is that they go so hot they popped right out of
> >their groves.
> >
> >We have tested every component of the system, Everyting works except these
> >elements. My theory is that they are lower voltage elements, hence lower
> >resistance, heat up way quick and pass the limit of the breaker.
> >
> >Any help appreciated before I call the company
> >
> >TIA
> >
> >Jonathan
> >
> >
> >
> >Jonathan Kaplan
> >Ceramic Design Group Ltd./Production Services
> >PO Box 775112
> >Steamboat Springs CO 80477
> >
> >(970) 879-9139*voice and fax
> Hi Jonathan,
If you haven't solved the kiln problem yet here are a few things to
check. It's possible that you did receive the wrong elements but from
your description there may be some other causes. First make sure the
kiln is disconnected from the main power. You can't measure the
resistance of an element while it's connected in the circuit so
disconnect one end of the element you wish to measure. If the
resistance is still 1/2 the spec value than it is the wrong element.
However, the fact that you said the resistance was 1/2 makes me think
that you measured it while it was connected in the circuit and what you
measured in effect was the equivalent resistance of two identical
elements wired in parallel. Also resistance will change as a function
of temperature, which in this case you really won't notice, so it's best
to measure them while they are cold. Carefully check the wiring dagram
to see if the elements are to be wired in series, parallel, or
series-parallel. Let me explain.
The voltage (E) equals the current (I) times the resistance (R)
E=IR, therefore, the current which you will draw is I=E/R so as the
resistance decreases the current increases. The equivalent resistance
of the circuit (all the kiln elements) changes as more elements are
switched on and off. If two identical resistances are connected in
parallel then the current has two identical paths to follow and the
equivalent resistance looks like 1/2 either resistance to the source of
power. So you can see by the above formula that if the resistance goes
down to 1/2 the current will double. You mentioned that when the kiln
reaches 600'F the 60 amp circuit breaker blows. It sounds like the
other elements are switching on in parallel and the current exceeds the
breaker value. To avoid excessive current draw heating elements are
many times wired in series and then the series combination is switched
on in parallel to other series elements. This series/parallel
arrangement can be modulated with the infinite switches available on the
controllers to reach the desired temperature without blowing the
breaker.
The heat produced, for all practical purposes in this case, is the power
in watts dissipated by the elements. The power (P)in watts equals the
Voltage (E) times the Current (I) or P=EI. Since E=IR you can
substitute into the previous equation and end up with P=I(IR). The
power increases as the square of the current. So, for example, if you
were to double the current you would actually quadruple the power. As
elements are switched on and off the resistance changes as does the
current (we'll assume that the voltage remains constant - I hate to
assume because you know what that makes *** - u -and me!). The changes
in current are then reflected as the square in the power produced.
I hope this hasn't been overly technical. If you can send a wiring
diagram or describe it on email I may be able to give you more help. I
also guess some of this might feed into the discussion on whether or not
we might need some basic facility with math as potters. I don't want to
get into that here but you might get a kick out of my tongue in cheek
pun which has been repeatedly dropped by the moderator. Even
Differential Calculus is easy - If you take if you take it a little bit
at a time! Let me know if there are any other questions which I might
be able to help you with. Just be sure to measure the element
resistance while it's OUT of the circuit i.e. by disconnecting one side.
Good Luck,
Paul Monaghan
paul@web2u.com
WEB2U Productions
web2u.com The COOLEST site on the Web
Talbott on sat 19 oct 96
>----------------------------Original message----------------------------
>At 10:26 PM 10/18/96 +0000, you wrote:
>>----------------------------Original message----------------------------
>>OK Kids! I have a rather vexing electrical element problem.
>>
>>We reccently rewired all our Paragon TnF 28-3 electric kilns. All work fine
>>except the last one we did yesterday.
>>Kiln specs. 240 volts 60 amp breaker kiln pulls around 48 or so. New
>>controller, all relays work fine, all wiring is fine, in short, everything
>>is ok, except that the top and bottom set of elements go right to red heat
>>at about 500 degrees f or so, the controllers works fine, and then when the
>>kiln gets to 600 degrees, the circuit breaker trips. When I use a
>>multimmeter to check the resistacen of each element, the readers are under
>>half of what then should be for new elements.
>>
>>Questions for the group: did the companysend me wrong elements..eg 220 volt
>>elements? ANother indicator is that they go so hot they popped right out of
>>their groves.
>>
>>We have tested every component of the system, Everyting works except these
>>elements. My theory is that they are lower voltage elements, hence lower
>>resistance, heat up way quick and pass the limit of the breaker.
>>
>>Any help appreciated before I call the company
>>
>>TIA
>>
>>Jonathan
>>
>>
>>
>>Jonathan Kaplan
>>Ceramic Design Group Ltd./Production Services
>>PO Box 775112
>>Steamboat Springs CO 80477
>>
>>(970) 879-9139*voice and fax
>
Jonathan,
208 volts is a 3 phase industrial voltage system and 240 volts is a 2
phase electrical system--- I believe---(I am not an electrician)---it
sounds like you have tried to convert your originally designed 3 phase
kilns into a 240 volt 2 phase system--You may have to change the
controllers and everything electrically controlling the current---Sounds
like you need to involve a master electrician to do the conversion
properly--good luck--Marshall
Marshall Talbott
Pottery By Celia
Route 114
P.O. Box 4116
Naples, Maine 04055-4116
(207)693-6100 voice and fax
clupus@ime.net
Jeanne Otis on sun 20 oct 96
>----------------------------Original message----------------------------
>OK Kids! I have a rather vexing electrical element problem.
>
>We reccently rewired all our Paragon TnF 28-3 electric kilns. All work fine
>except the last one we did yesterday.
>Kiln specs. 240 volts 60 amp breaker kiln pulls around 48 or so. New
>controller, all relays work fine, all wiring is fine, in short, everything
>is ok, except that the top and bottom set of elements go right to red heat
>at about 500 degrees f or so, the controllers works fine, and then when the
>kiln gets to 600 degrees, the circuit breaker trips. When I use a
>multimmeter to check the resistacen of each element, the readers are under
>half of what then should be for new elements.
>
>Questions for the group: did the companysend me wrong elements..eg 220 volt
>elements? ANother indicator is that they go so hot they popped right out of
>their groves.
>
>We have tested every component of the system, Everyting works except these
>elements. My theory is that they are lower voltage elements, hence lower
>resistance, heat up way quick and pass the limit of the breaker.
>
>Any help appreciated before I call the company
>
>TIA
>
>Jonathan
I have had a similar problem in rewiring used electric kilns, especially
ones with controllers on them. What I would look at is how many elements
or circuits were connected to an individual switch. If you have somehow
separated out one circuit, when two were required, you have actually cut
your resistance in half which would account for the immediate red heat.
This happened to me in wiring a Cress until I understood what was going on.
Also, the Oak switch, which Skutt uses, explains that it "shunts" two
circuits together internally within the switch, allowing it to run on 1/2
power on both circuits on low, full power on one circuit on medium, and
full power on two circuits for high. I hope this helps.
Jeanne Otis
David Woodin clayart Digest on sun 20 oct 96
If your kiln plugs into the receptacle you could unplug it and read the ohms
with your multimeter. All switches on low read about 19.5 ohms, all switches
on medium read about 9.5 ohms and all switches on high read about 5 ohms. If
it is hard wired to a circuit breaker you may rather have an electrician look
at it.
Fred G. Athearn on thu 24 oct 96
Kaplan> We reccently rewired all our Paragon TnF 28-3
Kaplan> electric kilns. All work fine except the last one we
Kaplan> did yesterday. [...] and then when the kiln gets to
Kaplan> 600 degrees, the circuit breaker trips.
Perhaps when the elements get hot they move and short out where
they go through and kiln jacket or inside the box.
--
Fred G. Athearn fga@sover.net http://www.sover.net/~fga
Rockingham, VT, USA finger for pgp key (802) 869-2003
| |
|
