Jennifer Boyer on fri 9 nov 07
OK, I really need help here:
The following is beyond my ability to understand:
I fired a usual bisk kiln in my L&L 2927 ( new switch panel 2 years
ago, original Kiln Sitter, maybe 15 years old)) on Wednesday. I had
a meeting in the evening after turning it to high, so went out and
then after the meeting checked to see that the kiln sitter had
dropped. All was well and I turned off the switches. The dial on the
kiln sitter showed a 7 hour time, the usual.
I had meetings Thursday and wasn't in the studio.
I went to the studio today, Friday and expected to be able to unload
the kiln. It was HOT! I looked in a peep and it was orange hot. It
had no noise, no elements buzzing. The sitter was still dropped and the
switches were off, as I had left it Wednesday night.
Jeez, what's going on?? Can enough systems break at once that
electricity goes to the elements without the switches being on and
without the sitter being set?
I had noticed a pretty intense buzzing in the switch box when I
turned the switches to high but I jiggled stuff and it went away. I
dread opening the kiln...I can't imagine how much electricity I ate
through if this kiln was on high for 2 days!
But I spent several hours in the studio today and wasn't hearing an
ON kiln....
I turned the kiln breaker off when I discovered the hot kiln today ....
I'll be in touch with L&L next week....
Anybody??
This is a first in 35 years of firing electrics...
Jennifer
*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************
Ron Roy on sat 10 nov 07
Hi Jennifer,
I can't help with understanding what happened but - I can tell you how you
could have avoided it.
All kilns should be hard wired (read - no plugs) to a shut off switch - so
that after each firing the shut off is used to disconnect the kiln from any
incoming current. Simple and easy and guaranteed to work if you use the
disconnect. I have mine wired so that a red light is on when the power is
flowing to the kiln - if the bulb is still working.
It become a habit after a while - and a red light is hard to ignore.
RR
>OK, I really need help here:
>The following is beyond my ability to understand:
>
>I fired a usual bisk kiln in my L&L 2927 ( new switch panel 2 years
>ago, original Kiln Sitter, maybe 15 years old)) on Wednesday. I had
>a meeting in the evening after turning it to high, so went out and
>then after the meeting checked to see that the kiln sitter had
>dropped. All was well and I turned off the switches. The dial on the
>kiln sitter showed a 7 hour time, the usual.
>
>I had meetings Thursday and wasn't in the studio.
>
>I went to the studio today, Friday and expected to be able to unload
>the kiln. It was HOT! I looked in a peep and it was orange hot. It
>had no noise, no elements buzzing. The sitter was still dropped and the
>switches were off, as I had left it Wednesday night.
>
>Jeez, what's going on?? Can enough systems break at once that
>electricity goes to the elements without the switches being on and
>without the sitter being set?
>
>I had noticed a pretty intense buzzing in the switch box when I
>turned the switches to high but I jiggled stuff and it went away. I
>dread opening the kiln...I can't imagine how much electricity I ate
>through if this kiln was on high for 2 days!
>But I spent several hours in the studio today and wasn't hearing an
>ON kiln....
>I turned the kiln breaker off when I discovered the hot kiln today ....
>I'll be in touch with L&L next week....
>Anybody??
>This is a first in 35 years of firing electrics...
>Jennifer
>
>*****************************
>Jennifer Boyer
>Thistle Hill Pottery
>Montpelier, VT
>http://thistlehillpottery.com
>*****************************
>
>______________________________________________________________________________
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
>You may look at the archives for the list, post messages, or change your
>subscription settings here: http://www.acers.org/cic/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Rogier Donker on sat 10 nov 07
No mystery at all... One of my schools just had a similar case... :
one or more of your infinite switches got stuck in the "on"
position.... happens.... NEVER EVER leave a firing kiln and expect
the shut off device to turn it off. Operator error..... when are you
going to learn??!! BE THERE when it is SUPPOSED TO TURN OFF!!
Rogier
P.S. See us on the web at http://www.donkerstudio.org
Alisha Clarke on sat 10 nov 07
I have my two electric kilns (L&L & Skutt) hard wired with shut off
switches. But they both have computer controllers. I've wondered if I
should be shutting off the power, but my concern is that I don't know
if the memory for the programs is maintained through an internal
battery or some sort of flash memory that doesn't need power. I would
hate to lose the programming by letting an internal battery wear down.
Does anyone know how this memory is maintained and whether cutting the
power for long periods is a good idea?
Leesh
~~~~~~~~~~~~~~~~~~~~~~~~~
Alisha Clarke
Pottery by Leesh: www.alishaclarke.com
Pottery Basics: www.potterybasics.com
On 11/10/07, Ron Roy wrote:
> Hi Jennifer,
>
> I can't help with understanding what happened but - I can tell you how you
> could have avoided it.
>
> All kilns should be hard wired (read - no plugs) to a shut off switch - so
> that after each firing the shut off is used to disconnect the kiln from any
> incoming current. Simple and easy and guaranteed to work if you use the
> disconnect. I have mine wired so that a red light is on when the power is
> flowing to the kiln - if the bulb is still working.
>
> It become a habit after a while - and a red light is hard to ignore.
>
> RR
--
Michael Wendt on sat 10 nov 07
Jennifer,
If your kiln has a kiln sitter
with the timer, the contact in the
timer may have fused in the
contacted position.
Someone else wrote that their
contacts almost always fail in the
open position, but my own experience
has been that they stick in the
contacted position so that even when
you want them to shut off, they don't.
If you open the kiln cover and find
this to be true, just replace the failed
contact and make sure that in future
you disconnect the breaker each time
the witness cones show the load is
done firing.
Calculating the electrical usage is fairly
easy:
For simplicity, use the name plate rating
for a close approximation.
Voltage (240) x Amperage(48 amps) x
hours of firing on high x your cost/kilowatt
hour (look on your power bill for this) =
the estimated maximum cost of firing.
You can buy a standard wattage meter and a
socket base for less than $100 that gives you
an actual kwh figure.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave.
Lewiston, Id 83501
U.S.A.
208-746-3724
wendtpot@lewiston.com
http://www.wendtpottery.com
http://UniquePorcelainDesigns.com
Lynn Goodman Porcelain Pottery on sat 10 nov 07
On Nov 10, 2007, at 8:59 AM, Alisha Clarke wrote:
> I have my two electric kilns (L&L & Skutt) hard wired with shut off
> switches. But they both have computer controllers. I've wondered if I
> should be shutting off the power, but my concern is that I don't know
> if the memory for the programs is maintained through an internal
> battery or some sort of flash memory that doesn't need power.
I have a friend whose controller re-started, then badly overfired her
kiln (of course, overnight when she wasn't there). I would definitely
shut the power off--the programming will not be lost, and you'll be
at no risk of this happening to you.
Lynn
Lynn Goodman
Fine Porcelain Pottery
Cell 347-526-9805
www.lynngoodmanporcelain.com
Lois Ruben Aronow on sat 10 nov 07
This is really good to know. My very wise studio mate turns her kiln off at
the box. We are not hard wired, but have *2* breaker switches. I've never
had a kiln turn back on at me, but this thread shows there is always a fist
time.
anyone know if any electrical costs are saved by flipping the switch? guess
I'm gonna find out.
> -----Original Message-----
> From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of
> Rogier Donker
> Sent: Saturday, November 10, 2007 8:49 AM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Electric Kiln MYSTERY
>
> No mystery at all... One of my schools just had a similar case... :
> one or more of your infinite switches got stuck in the "on"
> position.... happens.... NEVER EVER leave a firing kiln and
> expect the shut off device to turn it off. Operator
> error..... when are you going to learn??!! BE THERE when it
> is SUPPOSED TO TURN OFF!!
>
> Rogier
>
> P.S. See us on the web at http://www.donkerstudio.org
>
> ______________________________________________________________
> ________________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or
> change your subscription settings here:
> http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
Jennifer Boyer on sat 10 nov 07
HI Michael,
Rob at L&L said the behavior is exactly what happens when a relay in
the panel fries. There's a relay for each zone and I had heard a loud
buzzing in the panel towards the end of the firing. So I'm ordering
one for the one zone that had uncontrolled juice to it and 2 more as
backups for the other zones. He wasn't worried about the kiln sitter.
In this situation the sitter was off: mechanism dropped, timer off.
But juice kept flowing to the top zone with the switches in the off
position.
And as I'm unloading this firing I'm seeing that only the very top
seems on the overfired side, but not bad. The cone in the sitter
looks normal, not drippy so it's clear that the top zone was firing
after everything looked OFF, but not the other 2 zones.
Lessons learned:
1. I'm getting a shutoff switch for the kiln.
2. The next time something weird happens I'm going to BREATH DEEP,
CALM DOWN and get observant. It's so easy to panic and to make
assumptions that aren't right. I should have been looking at the
whole kiln and whether the zones were acting the same. I assumed that
the whole kiln had overfired, but it was only the top zone.
3. I should pay attention to anomalies: I should have been on the
alert after hearing that buzzing, even though it stopped.
4. I shouldn't be overconfident about fairly new equipment. The
switch panel was pretty new: under 5 years old.
SO many lessons, so little time....
Jennifer
PS. I have also had trouble with my Dawson sitter sticking in the
past. The behavior was that the mechanism never dropped so the sitter
never turned the kiln off. When I opened the kiln the cone was
melted in an overfired blob on the bar and fork part. The sitter
wasn't broken, just misbehaved. The timer kept going.
Murphy's law is alive and well. I hope this detailed description
helps someone else!
On Nov 10, 2007, at 10:53 AM, Michael Wendt wrote:
> Jennifer,
> If your kiln has a kiln sitter
> with the timer, the contact in the
> timer may have fused in the
> contacted position.
> Someone else wrote that their
> contacts almost always fail in the
> open position, but my own experience
> has been that they stick in the
> contacted position so that even when
> you want them to shut off, they don't.
*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************
KATHI LESUEUR on sat 10 nov 07
On Nov 10, 2007, at 1:14 PM, Jennifer Boyer wrote:
> HI Michael,
> Rob at L&L said the behavior is exactly what happens when a relay in
> the panel fries. There's a relay for each zone and I had heard a loud
> buzzing in the panel towards the end of the firing.....
> Lessons learned:
> 1. I'm getting a shutoff switch for the kiln.
> 2. The next time something weird happens I'm going to BREATH DEEP,
> CALM DOWN and get observant. It's so easy to panic and to make
> assumptions that aren't right. I should have been looking at the
> whole kiln and whether the zones were acting the same. I assumed that
> the whole kiln had overfired, but it was only the top zone.
> 3. I should pay attention to anomalies: I should have been on the
> alert after hearing that buzzing, even though it stopped.
> 4. I shouldn't be overconfident about fairly new equipment. The
> switch panel was pretty new: under 5 years old.>>>
Just yesterday I got an error message on my Evenheat kiln. It
wouldn't go above 1600. I know from the past and from the error code
that this is a thermocouple issue. I love the ease of a controller,
but at this point I think my next kiln will go back to standard
switches and cones. I have an old Crusader (twenty years). I've never
rewired it, never replaced the switches. It just keeps on working day
in and day out. I only fire bisque it to which helps. But I'm tired
of firings being interrupted by thermocouples, bad contollers, and
stuck relays. If I'm going to have to be around it when it fires, I
might as well just return to the simplicity of switches and stop
worrying.
Kathi
>
Larry Kruzan on sat 10 nov 07
Hi Jennifer,
I would recommend a power "disconnect" instead of using the breaker as a
switch. Breakers are not designed to be used as switches, they are a safety
device and like most safety devices they are engineered for a specific
purpose - shutting off power if a problem develops. Repeated switching
weakens the mechanism and will cause failure.
A power disconnect box will contain knife blade switch rated for repeated
use at current capacity - means you can pull the handle down in an emergency
without getting a flash burn - breakers may not have this feature. It also
may have a fuse holder for tubular fuses - This may seem redundant since you
have a breaker BUT this do go wrong sometimes. All industrial equipment is
set up this way.
If you are comfortable with electrical work this can be a do-it-yourself
project but do check with your local inspections dept - they may have other
ideas. The disconnect costs around $40 at any home improvement center -
insert note about asking for assistance from somebody who knows the
difference between a disconnect and a breaker.
NOTE!! Use only copper wire!!!!
Feel free to Email me with any questions.
Larry Kruzan
Lost Creek Pottery
www.lostcreekpottery.com
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Jennifer Boyer
Sent: Saturday, November 10, 2007 12:14 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: [CLAYART] Electric Kiln MYSTERY
HI Michael,
Rob at L&L said the behavior is exactly what happens when a relay in
the panel fries. There's a relay for each zone and I had heard a loud
buzzing in the panel towards the end of the firing. So I'm ordering
one for the one zone that had uncontrolled juice to it and 2 more as
backups for the other zones. He wasn't worried about the kiln sitter.
In this situation the sitter was off: mechanism dropped, timer off.
But juice kept flowing to the top zone with the switches in the off
position.
And as I'm unloading this firing I'm seeing that only the very top
seems on the overfired side, but not bad. The cone in the sitter
looks normal, not drippy so it's clear that the top zone was firing
after everything looked OFF, but not the other 2 zones.
Lessons learned:
1. I'm getting a shutoff switch for the kiln.
2. The next time something weird happens I'm going to BREATH DEEP,
CALM DOWN and get observant. It's so easy to panic and to make
assumptions that aren't right. I should have been looking at the
whole kiln and whether the zones were acting the same. I assumed that
the whole kiln had overfired, but it was only the top zone.
3. I should pay attention to anomalies: I should have been on the
alert after hearing that buzzing, even though it stopped.
4. I shouldn't be overconfident about fairly new equipment. The
switch panel was pretty new: under 5 years old.
SO many lessons, so little time....
Jennifer
PS. I have also had trouble with my Dawson sitter sticking in the
past. The behavior was that the mechanism never dropped so the sitter
never turned the kiln off. When I opened the kiln the cone was
melted in an overfired blob on the bar and fork part. The sitter
wasn't broken, just misbehaved. The timer kept going.
Murphy's law is alive and well. I hope this detailed description
helps someone else!
On Nov 10, 2007, at 10:53 AM, Michael Wendt wrote:
> Jennifer,
> If your kiln has a kiln sitter
> with the timer, the contact in the
> timer may have fused in the
> contacted position.
> Someone else wrote that their
> contacts almost always fail in the
> open position, but my own experience
> has been that they stick in the
> contacted position so that even when
> you want them to shut off, they don't.
*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************
____________________________________________________________________________
__
Clayart members may send postings to: clayart@lsv.ceramics.org
You may look at the archives for the list, post messages, or change your
subscription settings here: http://www.acers.org/cic/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots2@visi.com
John Sankey on sun 11 nov 07
"Rob at L&L said the behavior is exactly what happens when a relay in
the panel fries. There's a relay for each zone and I had heard a loud
buzzing in the panel towards the end of the firing. So I'm ordering
one for the one zone that had uncontrolled juice to it and 2 more as
backups for the other zones. He wasn't worried about the kiln sitter.
In this situation the sitter was off: mechanism dropped, timer off.
But juice kept flowing to the top zone with the switches in the off
position."
In my kiln, the sitter is a SAFETY device, precisely as Dawson
designed it - it turns the power off to EVERYTHING. I have to
assume that in L&L kilns, the sitter is used improperly, solely
as a signal to their all-power computer. I've worked with
computers for half a century now - I NEVER trust them as safety
devices!
L&L ought to correct the wiring in their kilns.
--
Include 'Byrd' in the subject line of your reply
to get through my spam filter.
Jennifer Boyer on sun 11 nov 07
Thanks Larry,
I'll be better prepared to talk to my electrician! I'm definitely
getting a power disconnect box asap...
Jennifer
On Nov 10, 2007, at 8:51 PM, Larry Kruzan wrote:
> Hi Jennifer,
>
> I would recommend a power "disconnect" instead of using the breaker
> as a
> switch. Breakers are not designed to be used as switches, they are
> a safety
> device and like most safety devices they are engineered for a specific
> purpose - shutting off power if a problem develops. Repeated
> switching
> weakens the mechanism and will cause failure.
>
> A power disconnect box will contain knife blade switch rated for
> repeated
> use at current capacity - means you can pull the handle down in an
> emergency
> without getting a flash burn - breakers may not have this feature.
> It also
> may have a fuse holder for tubular fuses - This may seem redundant
> since you
> have a breaker BUT this do go wrong sometimes. All industrial
> equipment is
> set up this way.
>
> If you are comfortable with electrical work this can be a do-it-
> yourself
> project but do check with your local inspections dept - they may
> have other
> ideas. The disconnect costs around $40 at any home improvement
> center -
> insert note about asking for assistance from somebody who knows the
> difference between a disconnect and a breaker.
>
> NOTE!! Use only copper wire!!!!
>
> Feel free to Email me with any questions.
>
> Larry Kruzan
> Lost Creek Pottery
> www.lostcreekpottery.com
>
>
>
>
>
> -----Original Message-----
> From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of
> Jennifer Boyer
> Sent: Saturday, November 10, 2007 12:14 PM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: [CLAYART] Electric Kiln MYSTERY
>
> HI Michael,
> Rob at L&L said the behavior is exactly what happens when a relay in
> the panel fries. There's a relay for each zone and I had heard a loud
> buzzing in the panel towards the end of the firing. So I'm ordering
> one for the one zone that had uncontrolled juice to it and 2 more as
> backups for the other zones. He wasn't worried about the kiln sitter.
> In this situation the sitter was off: mechanism dropped, timer off.
> But juice kept flowing to the top zone with the switches in the off
> position.
>
>
> And as I'm unloading this firing I'm seeing that only the very top
> seems on the overfired side, but not bad. The cone in the sitter
> looks normal, not drippy so it's clear that the top zone was firing
> after everything looked OFF, but not the other 2 zones.
>
> Lessons learned:
> 1. I'm getting a shutoff switch for the kiln.
> 2. The next time something weird happens I'm going to BREATH DEEP,
> CALM DOWN and get observant. It's so easy to panic and to make
> assumptions that aren't right. I should have been looking at the
> whole kiln and whether the zones were acting the same. I assumed that
> the whole kiln had overfired, but it was only the top zone.
> 3. I should pay attention to anomalies: I should have been on the
> alert after hearing that buzzing, even though it stopped.
> 4. I shouldn't be overconfident about fairly new equipment. The
> switch panel was pretty new: under 5 years old.
>
> SO many lessons, so little time....
> Jennifer
>
> PS. I have also had trouble with my Dawson sitter sticking in the
> past. The behavior was that the mechanism never dropped so the sitter
> never turned the kiln off. When I opened the kiln the cone was
> melted in an overfired blob on the bar and fork part. The sitter
> wasn't broken, just misbehaved. The timer kept going.
>
>
> Murphy's law is alive and well. I hope this detailed description
> helps someone else!
>
> On Nov 10, 2007, at 10:53 AM, Michael Wendt wrote:
>
>> Jennifer,
>> If your kiln has a kiln sitter
>> with the timer, the contact in the
>> timer may have fused in the
>> contacted position.
>> Someone else wrote that their
>> contacts almost always fail in the
>> open position, but my own experience
>> has been that they stick in the
>> contacted position so that even when
>> you want them to shut off, they don't.
>
> *****************************
> Jennifer Boyer
> Thistle Hill Pottery
> Montpelier, VT
> http://thistlehillpottery.com
> *****************************
>
> ______________________________________________________________________
> ______
> __
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or change
> your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
>
> ______________________________________________________________________
> ________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or change
> your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************
Alisha Clarke on sun 11 nov 07
Thank you Lynn and Vantuil,
I just shut off the power and will continue to do so after hearing these
horror stories.
Leesh
~~~~~~~~~~~~~~~~~~~~~~~~~
Alisha Clarke
Pottery by Leesh: www.alishaclarke.com
Pottery Basics: www.potterybasics.com
On 11/10/07, Lynn Goodman Porcelain Pottery wrote:
>
> On Nov 10, 2007, at 8:59 AM, Alisha Clarke wrote:
>
> > I have my two electric kilns (L&L & Skutt) hard wired with shut off
> > switches. But they both have computer controllers. I've wondered if I
> > should be shutting off the power, but my concern is that I don't know
> > if the memory for the programs is maintained through an internal
> > battery or some sort of flash memory that doesn't need power.
>
> I have a friend whose controller re-started, then badly overfired her
> kiln (of course, overnight when she wasn't there). I would definitely
> shut the power off--the programming will not be lost, and you'll be
> at no risk of this happening to you.
>
> Lynn
>
>
> Lynn Goodman
> Fine Porcelain Pottery
> Cell 347-526-9805
> www.lynngoodmanporcelain.com
>
>
> ______________________________________________________________________________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or change your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
>
--
Jennifer Boyer on sun 11 nov 07
Well, that was why I was so freaked out when this happened. I thought
the Dawson sitter created a complete cuttoff of the power when dropped.
I'll ask L&L about this when I talk to them again tomorrow...
Jennifer
On Nov 11, 2007, at 8:05 AM, John Sankey wrote:
> "Rob at L&L said the behavior is exactly what happens when a relay in
> the panel fries. There's a relay for each zone and I had heard a loud
> buzzing in the panel towards the end of the firing. So I'm ordering
> one for the one zone that had uncontrolled juice to it and 2 more as
> backups for the other zones. He wasn't worried about the kiln sitter.
> In this situation the sitter was off: mechanism dropped, timer off.
> But juice kept flowing to the top zone with the switches in the off
> position."
>
Byrd wrote:
> In my kiln, the sitter is a SAFETY device, precisely as Dawson
> designed it - it turns the power off to EVERYTHING. I have to
> assume that in L&L kilns, the sitter is used improperly, solely
> as a signal to their all-power computer. I've worked with
> computers for half a century now - I NEVER trust them as safety
> devices!
>
> L&L ought to correct the wiring in their kilns.
>
> --
> Include 'Byrd' in the subject line of your reply
> to get through my spam filter.
>
> ______________________________________________________________________
> ________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or change
> your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************
Jennifer Boyer on mon 12 nov 07
Ok,
I talked to Rob at L&L and he explained: my J2927 is a large kiln(11
cu ft) and is configured differently from the smaller kilns out
there. It has relays that control the power to the switches. Also the
Dawson Sitter is controlling the electricity that powers the
switches, not the power to the elements. This means that even though
the power is cut to the switches, if the relay sticks, it still
allows the power to flow through to the element of that zone. My
relay stuck in the closed position, which allows power to flow to the
element. Usually they stick open, which breaks the circuit. It's
unusual for relays to stick, but one reason is that the power flow is
a little lower than the optimum amount.
I'm going to take the control panel off the kiln and send it to L&L
so they can switch out all my relays and replace them with relays
that can handle lower power flow in a better way.
There you have it. It means that all you folks with smaller kilns can
relax. You probably don't have relays so this won't happen to you!
Jennifer, getting out the WD40 and screw drivers.
On Nov 11, 2007, at 8:05 AM, John Sankey wrote:
> "Rob at L&L said the behavior is exactly what happens when a relay in
> the panel fries. There's a relay for each zone and I had heard a loud
> buzzing in the panel towards the end of the firing. So I'm ordering
> one for the one zone that had uncontrolled juice to it and 2 more as
> backups for the other zones. He wasn't worried about the kiln sitter.
> In this situation the sitter was off: mechanism dropped, timer off.
> But juice kept flowing to the top zone with the switches in the off
> position."
>
> In my kiln, the sitter is a SAFETY device, precisely as Dawson
> designed it - it turns the power off to EVERYTHING. I have to
> assume that in L&L kilns, the sitter is used improperly, solely
> as a signal to their all-power computer. I've worked with
> computers for half a century now - I NEVER trust them as safety
> devices!
>
> L&L ought to correct the wiring in their kilns.
>
> --
> Include 'Byrd' in the subject line of your reply
> to get through my spam filter.
>
> ______________________________________________________________________
> ________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or change
> your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
*****************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
*****************************
Arnold Howard on mon 12 nov 07
From: "Lynn Goodman Porcelain Pottery"
> I have a friend whose controller re-started, then badly
> overfired her
> kiln (of course, overnight when she wasn't there).
------------
It's a good idea to leave the lid closed, too, while you are
not using the kiln. If the kiln turns on while you are away
(i.e., by a curious child) and the lid is closed, the kiln
will safely contain the heat. In the worst case, the
elements will fire until they burn themselves out.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
Arnold Howard on mon 12 nov 07
From: "Alisha Clarke"
I don't know
> if the memory for the programs is maintained through an
> internal
> battery or some sort of flash memory
--------------
Alisha, disconnecting the earliest controller erased the
program. (That was the DTC 100 series that Paragon made.)
The newer controllers all retain the programs in flash
memory, so nothing is erased when you unplug the kiln.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
Arnold Howard on mon 12 nov 07
From: "KATHI LESUEUR"
> Just yesterday I got an error message on my Evenheat kiln.
> It
> wouldn't go above 1600. I know from the past and from the
> error code
> that this is a thermocouple issue.
----------
Kathi, if you fire to cone 6, it would be cost effective to
upgrade to an S-Type thermocouple. That would eliminate one
of the weak points in the digital controller system.
The K-Type is fine only for low temperatures. Glass artists,
who fire to around 1500F, rarely have problems with the
K-Type.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
Alisha Clarke on mon 12 nov 07
Thanks Arnold!
I knew the memory was preserved for some time, but was afraid that it may
just be backed up with a battery which could wear down over time. If it's
flash memory, that shouldn't be a problem.
Following the recommendations in this thread, I'll be cutting the power
in-between firings from now on.
Leesh
~~~~~~~~~~~~~~~~~~~~~~~~~
Alisha Clarke
Pottery by Leesh: www.alishaclarke.com
Pottery Basics: www.potterybasics.com
On 11/12/07, Arnold Howard wrote:
>
> From: "Alisha Clarke"
> I don't know
> > if the memory for the programs is maintained through an
> > internal
> > battery or some sort of flash memory
> --------------
> Alisha, disconnecting the earliest controller erased the
> program. (That was the DTC 100 series that Paragon made.)
> The newer controllers all retain the programs in flash
> memory, so nothing is erased when you unplug the kiln.
>
> Sincerely,
>
> Arnold Howard
> Paragon Industries, L.P., Mesquite, Texas USA
> ahoward@paragonweb.com / www.paragonweb.com
>
>
> ______________________________________________________________________________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or change your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
>
--
Arnold Howard on mon 12 nov 07
From: "Jennifer Boyer"
> There you have it. It means that all you folks with
> smaller kilns can
> relax. You probably don't have relays so this won't happen
> to you!
----------
Digital kilns use relays, too. If the kiln has only one
relay and the relay fails in the "on" position, the kiln
could overfire. Kilns with two or more relays are less
likely to overfire, because a failed relay will turn on only
part of the power. This is why Jennifer's kiln only slightly
overfired in one section.
Getting the optional mercury relays instead of the
mechanical is another way to make a digital kiln extra
reliable. Mercury relays are especially nice if you program
slow coolings, which add hours of frequent on-off cycles to
the relays.
Jennifer, would you let us know how your kiln turns out?
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
Hank Taylor on tue 13 nov 07
Hi jennifer,
As long as they are going to change out the relays, Why can't they wire
it so the kiln setter would cut the high voltage power going to the relays.
That way even if the computer brain malfunctioned or the relays got hung ,
the elements would be shut off completely when the cone (maybe 1 cones
warmer than your target temp) bent or when the timer reached its limit.
That is the way the dawson kiln setter is designed to work. the way it is
wired now pretty much makes it useless.
Just my opinion,
Hank Taylor,
Woodshed Pottery
----- Original Message -----
From: "Jennifer Boyer"
To:
Sent: Monday, November 12, 2007 11:34 AM
Subject: Re: Electric Kiln MYSTERY
> Ok,
> I talked to Rob at L&L and he explained: my J2927 is a large kiln(11
> cu ft) and is configured differently from the smaller kilns out
> there. It has relays that control the power to the switches. Also the
> Dawson Sitter is controlling the electricity that powers the
> switches, not the power to the elements. This means that even though
> the power is cut to the switches, if the relay sticks, it still
> allows the power to flow through to the element of that zone.
Arnold Howard on wed 14 nov 07
From: "Hank Taylor"
> As long as they are going to change out the relays, Why
> can't they wire
> it so the kiln setter would cut the high voltage power
> going to the relays.
The Kiln Sitter can be equipped with a contact block rated
to 50 amps or 75 amps. If the kiln pulls over 50 amps,
specify that you want the Kiln Sitter with the 75 amp
contact block. Then the Sitter can be wired to shut off all
the power instead of only 50 amps of power.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
WJ Seidl on thu 15 nov 07
Arnold and all:
There is no need to wire power directly into the kiln sitter...that's
not its job. Its job is to shut the kiln off in case of overheating,
depending on what cone or bar you load into it. It is a failsafe, not
an on/off switch.
Having been involved in the machine tool industry for many years, I can
tell you that it would be to the kiln manufacturer's advantage (on
liability issues alone) to wire incoming power directly into a contactor
capable of handling the full load of the kiln. The coil of that
contactor (which normally draws less than an amp) could then be easily
controlled by the kiln sitter/timer/computer controller.
That way, off is OFF; all power shut down. When contactors fail, they
fail OFF, not stuck on, assuming that one has used "normally open"
contacts for the load (not making a connection when the power is off),
not normally closed contacts (making a connection when the power is
off), and not used a latching contact on the contactor itself (to keep
the coil energized once power is applied). A contactor capable of
pulling a 100 amp load will add about $150 max (retail) to the cost of a
kiln including the box and associated wiring. Probably less, when you
figure quantity discounts to the manufacturer. (I saw one on Ebay this
morning for $30)
Is it worth an extra $150 to avoid a house or studio fire? Ask anyone
who has been through one...see what they say.
Best,
Wayne Seidl
Arnold Howard wrote:
> From: "Hank Taylor"
>> As long as they are going to change out the relays, Why
>> can't they wire
>> it so the kiln setter would cut the high voltage power
>> going to the relays.
>
> The Kiln Sitter can be equipped with a contact block rated
> to 50 amps or 75 amps. If the kiln pulls over 50 amps,
> specify that you want the Kiln Sitter with the 75 amp
> contact block. Then the Sitter can be wired to shut off all
> the power instead of only 50 amps of power.
>
> Sincerely,
>
> Arnold Howard
> Paragon Industries, L.P., Mesquite, Texas USA
> ahoward@paragonweb.com / www.paragonweb.com
>
> ______________________________________________________________________________
>
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or change your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
>
Marni Turkel on thu 15 nov 07
I have 5 kilns wired so that when the kiln sitter trips, all power is
cut off to all of the relays in the kiln, they are all Skutts both 7
cubic feet and 11 cubic feet. These are old kilns, bought long before
computer controllers were available, so they have been retrofitted.
Originally they were wired so that the power to each section went
through the original switches and then to the relays, but now most
are wired so they bypass the switches. The timer and Kilnsitter work
exactly as they did before the retrofit.
The explanation below just doesn't make sense to me.
At 12:00 AM -0500 11/15/07, Automatic digest processor wrote:
> > I talked to Rob at L&L and he explained: my J2927 is a large kiln(11
>> cu ft) and is configured differently from the smaller kilns out
>> there. It has relays that control the power to the switches. Also the
>> Dawson Sitter is controlling the electricity that powers the
>> switches, not the power to the elements. This means that even though
>> the power is cut to the switches, if the relay sticks, it still
> > allows the power to flow through to the element of that zone.
--
Marni Turkel
2080 Llano Rd 1B
Santa Rosa, CA 95407
Phone 707-579-5567
Fax 707-579-1116
Stony Point Ceramic Design
http://www.marniturkel.com
Sonoma Urn Company
http://www.sonomaurn.com
Jim Willett on thu 15 nov 07
On Thu, 15 Nov 2007 07:38:05 -0500, WJ Seidl wrote:
...(SNIP) wire incoming power directly into a contactor
>capable of handling the full load of the kiln. The coil of that
>contactor (which normally draws less than an amp) could then be easily
>controlled by the kiln sitter/timer/computer controller.
>
>That way, off is OFF; all power shut down. When contactors fail, they
>fail OFF, not stuck on, assuming that one has used "normally open"
>contacts for the load (not making a connection when the power is off),
>not normally closed contacts (making a connection when the power is
>off), and not used a latching contact on the contactor itself (to keep
>the coil energized once power is applied). A contactor capable of
>pulling a 100 amp load will add about $150 max (retail) to the cost of a
>kiln including the box and associated wiring. Probably less, when you
>figure quantity discounts to the manufacturer. (I saw one on Ebay this
>morning for $30)...(SNIP)
>
>
Just a quick two cents worth here...I thought that was the way they were
always installed. We bought an old kiln a few years ago with a kiln sitter
and no instructions. I just naturally wired it that way. It was news to
hear everyone wasn't doing it. Wayne's description is exactly right.
Jim
Hank Taylor on thu 15 nov 07
Hi all,
Mr. Seidl , I must disagree with you on a couple of points
in your reply to " Arnold and all " . First the job of the kiln sitter is
precisiely to SHUT DOWN the kiln, either by a bar or cone bending ( which
causes the kiln to shut down upon reaching the * DESIRED TEMP * , not
because it is over heating) or by a time -limit that the kiln can reach (
the time it usually takes to reach the specific cone temp + a little extra
time in case the kiln load is a little denser ) thereby preventing a
run-away kiln like the one we are discussing. If you do not bring the
element power through the kilnsitter then it can't protect it from a
run-away problem.
Also I disagree about the relays.When the contactors fail, they
usually fail to release, because the contact points cam become pitted and
rough ( guaranteed to happen if you try to run a fifty amp kiln through a
30 amp kiln sitter), reducing the power capabilities it can carry and it
begins arcing more and more each time they make or break the connection.
When the surfaces heat up enough it will finally start melting the contact
points and they will "weld" themselves together, causing the current to
continue to flow whether the computer is sending a signal or not. This is
what happened to this kiln , only just one relay failed. If the coil had
failed, then the contact would not have been made and the elements would
have not heated up. The industry usually is driven by the bottom line
Numbers an not concerned with liability any more, They just declare BR if
they get sued and open a new store across the city. It is much cheaper on
them to use a sitter to turn 5 amps on and off , instead of one to handle 40
+ amps. In the last 20 years as a self-employed contractor, I've seen 10
times as many welded relays as I have seen relays where the coils developed
an open circuit and not pull the contacts together. Down here , the fire
ants are supposedly attracted to the current flow in the A/C condensers and
they crawl into the contactor boxes and start the arcing with fried ant rear
ends. I have replaced around 300 or so of relays over the years since I
worked for Allen Electric back in my younger years.(30 yrs ago)
Just My advice . It and a buck fifty will buy you coffee down here
Hank Taylor
Woodshed Pottery
Central Mississippi
----- Original Message -----
From: "WJ Seidl"
To:
Sent: Thursday, November 15, 2007 6:38 AM
Subject: Re: Electric Kiln MYSTERY
> Arnold and all:
> There is no need to wire power directly into the kiln sitter...that's
> not its job. Its job is to shut the kiln off in case of overheating,
> depending on what cone or bar you load into it. It is a failsafe, not
> an on/off switch.
> Having been involved in the machine tool industry for many years, I can
> tell you that it would be to the kiln manufacturer's advantage (on
> liability issues alone) to wire incoming power directly into a contactor
> capable of handling the full load of the kiln. The coil of that
> contactor (which normally draws less than an amp) could then be easily
> controlled by the kiln sitter/timer/computer controller.
>
> That way, off is OFF; all power shut down. When contactors fail, they
> fail OFF, not stuck on, assuming that one has used "normally open"
> contacts for the load (not making a connection when the power is off),
> not normally closed contacts (making a connection when the power is
> off), and not used a latching contact on the contactor itself (to keep
> the coil energized once power is applied). A contactor capable of
> pulling a 100 amp load will add about $150 max (retail) to the cost of a
> kiln including the box and associated wiring. Probably less, when you
> figure quantity discounts to the manufacturer. (I saw one on Ebay this
> morning for $30)
>
> Is it worth an extra $150 to avoid a house or studio fire? Ask anyone
> who has been through one...see what they say.
> Best,
> Wayne Seidl
>
> Arnold Howard wrote:
>> From: "Hank Taylor"
>>> As long as they are going to change out the relays, Why
>>> can't they wire
>>> it so the kiln setter would cut the high voltage power
>>> going to the relays.
>>
>> The Kiln Sitter can be equipped with a contact block rated
>> to 50 amps or 75 amps. If the kiln pulls over 50 amps,
>> specify that you want the Kiln Sitter with the 75 amp
>> contact block. Then the Sitter can be wired to shut off all
>> the power instead of only 50 amps of power.
>>
>> Sincerely,
>>
>> Arnold Howard
>> Paragon Industries, L.P., Mesquite, Texas USA
>> ahoward@paragonweb.com / www.paragonweb.com
>>
>> ______________________________________________________________________________
>>
>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list, post messages, or change your
>> subscription settings here: http://www.acers.org/cic/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>> melpots2@visi.com
>>
>
> ______________________________________________________________________________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, or change your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
>
>
> --
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.503 / Virus Database: 269.15.32/1131 - Release Date:
> 11/14/2007 4:54 PM
>
>
Arnold Howard on thu 15 nov 07
From: "WJ Seidl"
A contactor capable of
> pulling a 100 amp load will add about $150 max (retail) to
> the cost of a
> kiln including the box and associated wiring.
A backup shutoff device is a great idea. I wonder if people
would be willing to pay the extra cost.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
John Sankey on fri 16 nov 07
"When contactors fail, they fail OFF"
WARNING - this is dangerously incorrect. Contacts often weld
closed when they overheat - I've seen many. That's what happened
to the original poster.
You need two independent contacts in series to be safe. If the
kiln manufacturer refuses to wire the sitter that way, then try
to find a separate wall-mounted timer to do the job. Emergencies
that blow people's mental organization, even accidents, happen.
You should never assume that something that can burn your house
down is going to be turned off manually by a disconnect switch
and nothing else.
I agree with Arnold Howard. The kiln sitter should be wired
with a properly rated contactor to do the job.
--
Include 'Byrd' in the subject line of your reply
to get through my spam filter.
WJ Seidl on fri 16 nov 07
Hank:
In the original post (unless I read it wrong,) Jennifer mentioned that
even though the kiln sitter had shut down, there was still power going
to one (more?) of the elements. If the kiln sitter were wired
"properly" to my way of thinking...in other words, wired in order to
make sure there was NO power to the kiln, that would not have occurred.
You can prevent a runaway condition by wiring the entire power of the
kiln through a contactor controlled by the kiln sitter, not by treating
the kiln sitter as some sort of automatic shut off switch. The kiln
sitter is not there to replace YOUR BRAIN. It is there to assist,
_in_case_ there is a problem.
You are correct in that relays do stick in the "on" position. I've seen
more than a few instances of that myself. Just this year, I replaced
four GFCI outlets in the house here contaminated with ant carcasses, and
two power relays in one of our trucks for the same reason. The little
b*st*rds get everywhere, don't they? While I was in there, I also got
rid of all the little lizard eggs in the electrical outlet boxes, too .
The solution to overcoming that sticking relay problem (and I hate to
keep beating an obviously dead and decomposing equine here, no matter
how amusing others find it) is to always be at the kiln when firing, and
do not expect it _not_ to fail. Unfortunately, your pessimistic view of
what industry would do in the case of a liability suit (declare
bankruptcy and move across the street and reopen) is the norm these
days. Were that it were not so. But they would not move, they would
just incorporate under a "slightly" different name, and stay right where
they were. They would probably not even lose a day's production. They
certainly would not care. That's what the lawyers are for (yeah, right).
Sad, really.
I've received quite a few e-mails to the effect that "Wayne, you need to
learn to trust equipment more" or "that's why I have insurance".
Sorry...no, I don't; and no, it isn't. I believe rather in Murphy's
law, because I KNOW from personal experience that Murphy's Law works. If
you trust machinery implicitly, you are putting your life and livelihood
fully in the hands of some minimum wage, unskilled or semi-skilled
worker who is more concerned about what (s)he has in his/her lunch
bucket than the job (s)he's doing and the quality of the machine (s)he's
building.
And that should scare the crap out of anyone.
I don't think our viewpoints are that far apart, Hank
Best,
Wayne Seidl
Hank Taylor wrote:
> Hi all,
>
> Mr. Seidl , I must disagree with you on a couple of
> points
> in your reply to " Arnold and all " . First the job of the kiln sitter is
> precisiely to SHUT DOWN the kiln, either by a bar or cone bending (
> which
> causes the kiln to shut down upon reaching the * DESIRED TEMP * , not
> because it is over heating) or by a time -limit that the kiln can
> reach (
> the time it usually takes to reach the specific cone temp + a little
> extra
> time in case the kiln load is a little denser ) thereby preventing a
> run-away kiln like the one we are discussing. If you do not bring the
> element power through the kilnsitter then it can't protect it from a
> run-away problem.
>
> Also I disagree about the relays.When the contactors fail,
> they
> usually fail to release, because the contact points cam become
> pitted and
> rough ( guaranteed to happen if you try to run a fifty amp kiln
> through a
> 30 amp kiln sitter), reducing the power capabilities it can carry and it
> begins arcing more and more each time they make or break the connection.
> When the surfaces heat up enough it will finally start melting the
> contact
> points and they will "weld" themselves together, causing the current to
> continue to flow whether the computer is sending a signal or not. This is
> what happened to this kiln , only just one relay failed. If the coil had
> failed, then the contact would not have been made and the elements would
> have not heated up. The industry usually is driven by the bottom line
> Numbers an not concerned with liability any more, They just declare BR if
> they get sued and open a new store across the city. It is much cheaper on
> them to use a sitter to turn 5 amps on and off , instead of one to
> handle 40
> + amps. In the last 20 years as a self-employed contractor, I've seen 10
> times as many welded relays as I have seen relays where the coils
> developed
> an open circuit and not pull the contacts together. Down here , the fire
> ants are supposedly attracted to the current flow in the A/C
> condensers and
> they crawl into the contactor boxes and start the arcing with fried
> ant rear
> ends. I have replaced around 300 or so of relays over the years since I
> worked for Allen Electric back in my younger years.(30 yrs ago)
>
> Just My advice . It and a buck fifty will buy you coffee down here
>
> Hank Taylor
> Woodshed Pottery
> Central Mississippi
>
>
>
> ----- Original Message -----
> From: "WJ Seidl"
> To:
> Sent: Thursday, November 15, 2007 6:38 AM
> Subject: Re: Electric Kiln MYSTERY
>
>
>> Arnold and all:
>> There is no need to wire power directly into the kiln sitter...that's
>> not its job. Its job is to shut the kiln off in case of overheating,
>> depending on what cone or bar you load into it. It is a failsafe, not
>> an on/off switch.
>> Having been involved in the machine tool industry for many years, I can
>> tell you that it would be to the kiln manufacturer's advantage (on
>> liability issues alone) to wire incoming power directly into a contactor
>> capable of handling the full load of the kiln. The coil of that
>> contactor (which normally draws less than an amp) could then be easily
>> controlled by the kiln sitter/timer/computer controller.
>>
>> That way, off is OFF; all power shut down. When contactors fail, they
>> fail OFF, not stuck on, assuming that one has used "normally open"
>> contacts for the load (not making a connection when the power is off),
>> not normally closed contacts (making a connection when the power is
>> off), and not used a latching contact on the contactor itself (to keep
>> the coil energized once power is applied). A contactor capable of
>> pulling a 100 amp load will add about $150 max (retail) to the cost of a
>> kiln including the box and associated wiring. Probably less, when you
>> figure quantity discounts to the manufacturer. (I saw one on Ebay this
>> morning for $30)
>>
>> Is it worth an extra $150 to avoid a house or studio fire? Ask anyone
>> who has been through one...see what they say.
>> Best,
>> Wayne Seidl
>>
>> Arnold Howard wrote:
>>> From: "Hank Taylor"
>>>> As long as they are going to change out the relays, Why
>>>> can't they wire
>>>> it so the kiln setter would cut the high voltage power
>>>> going to the relays.
>>>
>>> The Kiln Sitter can be equipped with a contact block rated
>>> to 50 amps or 75 amps. If the kiln pulls over 50 amps,
>>> specify that you want the Kiln Sitter with the 75 amp
>>> contact block. Then the Sitter can be wired to shut off all
>>> the power instead of only 50 amps of power.
>>>
>>> Sincerely,
>>>
>>> Arnold Howard
>>> Paragon Industries, L.P., Mesquite, Texas USA
>>> ahoward@paragonweb.com / www.paragonweb.com
>>>
>>> ______________________________________________________________________________
>>>
>>>
>>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>>
>>> You may look at the archives for the list, post messages, or change
>>> your
>>> subscription settings here: http://www.acers.org/cic/clayart/
>>>
>>> Moderator of the list is Mel Jacobson who may be reached at
>>> melpots2@visi.com
>>>
>>
>> ______________________________________________________________________________
>>
>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list, post messages, or change your
>> subscription settings here: http://www.acers.org/cic/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>> melpots2@visi.com
>>
>>
>> --
>> No virus found in this incoming message.
>> Checked by AVG Free Edition.
>> Version: 7.5.503 / Virus Database: 269.15.32/1131 - Release Date:
>> 11/14/2007 4:54 PM
>>
>>
>
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Eleanora Eden on sat 17 nov 07
My kiln already has an external power shut off, actually a 3 way that sends
it to the controller, to the kiln, or shuts it off. But I hadn't thought of the red
light and I promptly had one put in. All backup systems are appreciated.
I had a different conundrum with my last firing. One of the pyros just didn't
register properly....the kiln went up to its low bisc and the top pyro still said
500F. I had to fire by color....in the low bisc I don't bother with cones.
When I unloaded we noticed that the top pyro was almost entirely covered
by the insulating porcelain. I have no idea why this never happened before.
So now on I have to make sure that all the little pyro tips are sticking out
as far as they go out of their protective sleeve.
Eleanora
>
>All kilns should be hard wired (read - no plugs) to a shut off switch - so
>that after each firing the shut off is used to disconnect the kiln from any
>incoming current. Simple and easy and guaranteed to work if you use the
>disconnect. I have mine wired so that a red light is on when the power is
>flowing to the kiln - if the bulb is still working.
>
>It become a habit after a while - and a red light is hard to ignore.
>
>RR
--
Bellows Falls Vermont
www.eleanoraeden.com
Larry Kruzan on sat 17 nov 07
That's right on, I've had about the same number of years working with
everything from missile launchers to flight simulators to every type of
manufacturing machine around - the only coils I've seen fail were fed
voltage beyond their specs. The one caveat to this statement is that we are
talking industrial equipment - not home use, Wal-Mart crap - with 15 cent
contactors in them. The contacts weld closed not open.
Back when I was at White Sands we would change contacts in some equipment
regularly - high amperage stuff - several hundred amps momentary.
The good old days!
Be your own safety device - stay focused on what you are doing - turn the
power off to the kiln manually every time - live long and make lots of pots.
Larry
Hank,
All the relay failures I have seen in the
35 years I have building heavy equipment
have also been welded contacts that would
not open.
The coils are impedance protected and almost never fail
no matter how long they run.
Regards,
Michael Wendt
Michael Wendt on sat 17 nov 07
Hank,
All the relay failures I have seen in the
35 years I have building heavy equipment
have also been welded contacts that would
not open.
The coils are impedance protected and almost never fail
no matter how long they run.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave.
Lewiston, Id 83501
U.S.A.
208-746-3724
wendtpot@lewiston.com
http://www.wendtpottery.com
http://UniquePorcelainDesigns.com
Hank wrote:
Also I disagree about the relays.When the
contactors fail, they
usually fail to release, because the contact points
cam become pitted and
rough ( guaranteed to happen if you try to run a fifty
amp kiln through a
30 amp kiln sitter), reducing the power capabilities it
can carry and it
begins arcing more and more each time they make or
break the connection.
When the surfaces heat up enough it will finally start
melting the contact
points and they will "weld" themselves together,
causing the current to
continue to flow whether the computer is sending a
signal or not. This is
what happened to this kiln , only just one relay
failed. If the coil had
failed, then the contact would not have been made and
the elements would
have not heated up. The industry usually is driven by
the bottom line
Numbers an not concerned with liability any more, They
just declare BR if
they get sued and open a new store across the city. It
is much cheaper on
them to use a sitter to turn 5 amps on and off ,
instead of one to handle 40
+ amps. In the last 20 years as a self-employed
contractor, I've seen 10
times as many welded relays as I have seen relays where
the coils developed
an open circuit and not pull the contacts together.
Down here , the fire
ants are supposedly attracted to the current flow in
the A/C condensers and
they crawl into the contactor boxes and start the
arcing with fried ant rear
ends. I have replaced around 300 or so of relays over
the years since I
worked for Allen Electric back in my younger years.(30
yrs ago)
Just My advice . It and a buck fifty will buy you
coffee down here
Hank Taylor
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