David Martin Hershey on tue 10 aug 04
Hi Earl, Ron, William, Arnold, & all
I also have had a relay failure like William was talking about.
I was informed of the fact by a frantic call from my assistant at 3 in the
morning. (She loves to work at night).
It seems that one of the three relays on my Skutt kiln had failed in the
closed position.(about this kilns 100th firing) The kiln was nearing the top
of a glaze firing, and the computer was showing an error message.
She had been instructed that if there was ever any problem with the kiln,
just to hit the STOP button on the controller.
What freaked her out was the fact that even after the kiln was "off", the
temp readout kept climbing.
I told her just to hit the nearby breaker, and went back to sleep.
The next day when I turned the breaker back on, the temp started to climb
immediately, even with the kiln "off".
When I opened the controller up, it was obvious which relay was bad. They
all had a bit of that smoked look to them, but the stuck one was black, and
you couldn't see through the plastic at all.
I just replaced all three of them to avoid having to deal with it again in
the near future.
The Skutt rep that I spoke with said that at the very worst, one stuck relay
would eventually cause one of the elements to fail after many many hours.
Thanks for the tip on the mercury relays William. Next time I will replace
with these, just to save the hassle of having to do it again. Not a hard
job, but time consuming, and the kiln is down until you get the new relay or
relays.
BTW: are the mercury relays silent?
Best, DMH
Beautiful Hermosa Beach CA USA
where I've been lost
in a haze of html
for a week
Arnold Howard on tue 10 aug 04
If the digital kiln gets too hot, the controller is designed to shut off the
kiln. This is one reason so few digital kilns overfire. Nevertheless,
overfires do happen.
When a relay fails, it usually fails in the "off" position. If a relay
sticks in the "on" position, the elements wired to that relay will remain
powered even though the controller has shut off the kiln. On a small kiln
with one relay, a stuck relay could result in an overfire since all the
elements will remain powered. On the larger kilns with two or three relays,
a single stuck relay will keep the temperature at a mid-range.
We have had pretty good luck with the P&B mechanical relay. But they, too,
are not fail-proof. This is why all kiln manufacturers warn not to leave a
kiln unattended.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
arnoldhoward@att.net / www.paragonweb.com
From: "William Melstrom"
> They aren't called breakers, they are called relays (there is a
difference),
> and they absolutely CAN stick in the closed, or "on" position. I have had
> it happen twice to me, on two different computer controlled Skutt kilns.
> The type of relay is commonly called a "cube" or "clear cube." Both
times,
> all I had to do was rap on the controller box to un-stick the relay (they
> did not "weld" shut).
> From: "Ron Roy"
> > I have heard the breakers can weld shut - if it happens at the end of
the
> > firing - would it not keep going?
Ron Roy on wed 11 aug 04
Excellent advice as usual from Howard.
Just to add - what I think is a crucial step.
When a firing is done - turn off the power to the kiln - at the breaker box
- another good reason to have your kiln hard wired.
If you don't have a shut off - get one.
If you are plugged in pull the plug - carefully - remember it's "live" till
it clears receptacle. This helps you in another way - if the plug is hot -
like too hot to hold - it is a warning that the connection is not right and
can result in a fire at the plug.
RR
>When a relay fails, it usually fails in the "off" position. If a relay
>sticks in the "on" position, the elements wired to that relay will remain
>powered even though the controller has shut off the kiln. On a small kiln
>with one relay, a stuck relay could result in an overfire since all the
>elements will remain powered. On the larger kilns with two or three relays,
>a single stuck relay will keep the temperature at a mid-range.
>
>We have had pretty good luck with the P&B mechanical relay. But they, too,
>are not fail-proof. This is why all kiln manufacturers warn not to leave a
>kiln unattended.
>
>Sincerely,
>
>Arnold Howard
>Paragon Industries, L.P., Mesquite, Texas USA
>arnoldhoward@att.net / www.paragonweb.com
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
William Melstrom on wed 11 aug 04
David wrote:
Thanks for the tip on the mercury relays William. Next time I will =
replace
with these, just to save the hassle of having to do it again. Not a hard
job, but time consuming, and the kiln is down until you get the new =
relay or
relays.
BTW: are the mercury relays silent?
David, I do not know if the mercury relays are silent. I do know that =
Skutt is offering them on new kilns, at a considerable cost increase. =
If you upgrade to mercury relays, you will need to replace the circuit =
board. -- William
Arnold Howard on wed 11 aug 04
Mercury relays are silent. However, if they require a "driver" mechanical
relay, you will still hear the clicking of a single relay.
In the case of Paragon's Dragon and Viking kilns, the Orton controller does
not power the mercury relays directly. Instead, it powers a driver
mechanical relay, which in turn powers the mercury relays.
If you decide to install mercury relays, be sure to get instructions from
the kiln manufacturer. You may need a driver relay too.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
arnoldhoward@att.net / www.paragonweb.com
----- Original Message -----
From: "David Martin Hershey"
> Thanks for the tip on the mercury relays William. Next time I will replace
> with these, just to save the hassle of having to do it again. Not a hard
> job, but time consuming, and the kiln is down until you get the new relay
or
> relays.
>
> BTW: are the mercury relays silent?
william schran on wed 11 aug 04
RR wrote:>If you are plugged in pull the plug - carefully - remember
it's "live" till
it clears receptacle. This helps you in another way - if the plug is hot -
like too hot to hold - it is a warning that the connection is not right and
can result in a fire at the plug.<
Hmmmm... I would think this practice would cause the receptacle
blades to loosen contact with the plug blades over time, thus causing
the heating problem.
Perhaps simply shutting off the breaker is the best of all solutions.
Of course, one would want to still be in the habit of checking the
plug for heat and condition on a consistent basis.
Bill
Maurice Weitman on wed 11 aug 04
Hello, all,
I've read many posts and articles saying that one shouldn't fire any
kiln unattended. That would be the safe thing to do, but I know I'm
not alone in wanting to sleep.
Of course, the quality of one's sleep is important, too.
One of my reasons for selecting the Bailey 2927-10 kiln I bought was
that it included a Kiln Sitter along with the Bartlett controller. I
sleep very well with a cone above the intended firing in the sitter.
Nothing is foolproof (remember hanging chads?), but redundancy does
help.
Other manufacturers may offer this as an option (Axner and L&L wanted
$375 extra), and the more adventuresome among us may be able to
retrofit one on any kiln for half that amount. It's not rocket
science.
In any event, one overfiring can easily cost a potter more then $400
in lost pots. I think it's a worthwhile investment.
About mercury relays... yes, they're quiet, unless you count the
"Ooof-da" you'll say when you see their price.
Long-term, they are likely a good investment, as are type-S
thermocouples, fluorescent bulbs, and flossing daily.
Best,
Maurice
william schran on thu 12 aug 04
Maurice wrote:>I've read many posts and articles saying that one
shouldn't fire any
kiln unattended. That would be the safe thing to do, but I know I'm
not alone in wanting to sleep.
One of my reasons for selecting the Bailey 2927-10 kiln I bought was
that it included a Kiln Sitter along with the Bartlett controller. I
sleep very well with a cone above the intended firing in the sitter.
Nothing is foolproof (remember hanging chads?), but redundancy does
help.<
I think the operative phrase here is: "nothing is foolproof".
Having redundancy and multiple back-ups is all well and good - until
that one time when they all fail.
Many years ago I was under the false impression: "It's ok, go home,
the kiln sitter will shut the kiln off."
This was a sitter with a timer!
That was until I returned one morning to find a glowing kiln, still going!
Waited 2 days to cool down to find a mass of molten clay, shelves
bent into "U" shapes and the kiln interior a disaster.
My motto now is: whatever can go wrong, will go wrong.
I'm sorry, I'll probably get flack from writing this, but I just gotta -
If you leave a kiln unattended, you are a fool.
Bill
Kathi LeSueur on fri 13 aug 04
wschran@COX.NET wrote:
> Maurice wrote:>I've read many posts and articles saying that one
> shouldn't fire any
> kiln unattended. That would be the safe thing to do, but I know I'm
> not alone in wanting to sleep.......>>>>
>
>
> <>
> I'm sorry, I'll probably get flack from writing this, but I just gotta -
> If you leave a kiln unattended, you are a fool.>>
>
>
An easy way around this problem of sleep and firing is to use the
"delay" setting on your kiln. I usually set the delay so that my
electric kiln starts in the middle of the night. That way I'm up and in
the studio when it is ready to finish.
Yes, sleep is desirable. But, those of us who fire gas would like to
sleep too. And, I doubt that any of us would leave our kilns to sleep.
Kathi
Ivor and Olive Lewis on fri 13 aug 04
Dear William,
You say, and I agree with you,.. << I think the operative phrase here
is: "nothing is foolproof"..,.>> Perhaps we should consider that the
corollary might be "Everything is Idiot Prone"
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
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