John Rodgers on thu 22 dec 05
Contact your local electric company and ask them to come and put a meter
on your kiln during one firing cycle. The meter has a coil that wraps
around the kiln electric cable, and senses the current draw. Every few
seconds the meter samples the current draw and records it. A paper
printout can be made available and this printout will show you exactly
what the kiln is doing, how much power is being used at any given time
in the firing cycle, total kilowatts used, etc, etc,. Well worth doing.
My local electric company came out and did this for me at no charge.
Regards,
John Rodgers
Chelsea, AL
nsmheralds@netzero.net wrote:
>Greetings unto the list. I have access to two older Skutt kilns, model 1326-208, I believe. They're about 12 cu ft. each and have manual controls. They need to be wired. Before that, I need to know what they're operating costs are likely to be. (The kilns are owned by the local Park and Rec folks, so it's one of those paperwork things.) Since electricity rates vary so much, what I really need is an estimate on how much electricity they're likely to use in terms of kWh for bisque fire (I typically bisque to 1650-1700 F), and cones 1, 6 and 8 glaze fire. The speed of my firing cycle will no doubt influence how much energy is used, but an average should be sufficient. Thanks.
>
>Nathan Miller
>Thistillium Pottery
>Newberg, OR
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
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>Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
>
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>
nsmheralds@netzero.net on thu 22 dec 05
Greetings unto the list. I have access to two older Skutt kilns, model =
1326-208, I believe. They're about 12 cu ft. each and have manual contr=
ols. They need to be wired. Before that, I need to know what they're o=
perating costs are likely to be. (The kilns are owned by the local Park=
and Rec folks, so it's one of those paperwork things.) Since electrici=
ty rates vary so much, what I really need is an estimate on how much ele=
ctricity they're likely to use in terms of kWh for bisque fire (I typica=
lly bisque to 1650-1700 F), and cones 1, 6 and 8 glaze fire. The speed =
of my firing cycle will no doubt influence how much energy is used, but =
an average should be sufficient. Thanks.
=
Nathan Miller
Thistillium Pottery
Newberg, OR
=
Bruce Lucas on fri 23 dec 05
John Rodgers wrote:
> Every few
> seconds the meter samples the current draw and records it.
I'd be a little cautious about this, depending on how your controller
works. My electric kiln controller cycles the power on and off on a
fixed 10-second cycle. That is, it regulates the heat output to a
certain percentage of the maximum heat output by turning the elements on
full blast for that percentage of each 10 second interval. If the meter
for example were also sampling at 10 second intervals, it could give a
very inaccurate result - if the samples happened to be near the
beginning of the kiln's 10 second intervals, the heating elements would
appear to be on continuously as far as the meter was concerned and so
the measurement would be much higher than reality, while if the samples
happened to be near the end of the kiln's 10 second intervals, the
heating elements would appear to be always be off as far as the meter
was concerned and so the measurement would be much too small. Kind of
like how a strobe light freezes motion. If the measurement interval
were 5 seconds compared to my kiln's cycle of 10 seconds the measurement
would still be inaccurate, but not as much so.
Here's an idea for getting an estimate without a meter, assuming a
controller of this type.
I've observed that the "duty cycle" (percentage of the time that the
heating elements are on) for my kiln rises steadily during a firing
cycle from nearly 0% to nearly 100%. You can tell this by listening to
the relay clicking. I think it reaches a 50% duty cycle well before
halfway through the firing, which means that the average duty cycle over
the course of the firing is going to be well over 50% but still well
below 100%.
So to get a rough estimate you might assume say a 75% average duty cycle
over the course of the firing and multiply that times the kilowatt
rating of the kiln times the length of the firing in hours to get the
number of kilowatt-hours of electricity consumed, which you can then
mulitply by the cost of electricity to get an estimate of the cost of a
firing.
You can compute the kilowatt rating of your kiln by multiplying the
current rating (in amps) times the voltage (likely 120, 208, or 240) and
divide by 1000.
Since we assumed a 75% duty cycle but only know for sure that the actual
average duty cycle is somewhere between 50% and 100%, we know for sure
that the actual cost is the estimated cost plus or minus a third. My
guesstimate is that the 75% average duty cycle estimate is actually not
too far off, at least for my kiln, so my guess is that the estimated
cost derived this way would be much closer to the actual cost than plus
or minus a third.
You could get a better estimate of the average duty cycle by observing
the duty cycle percentage say every hour over the course of a firing by
listening to the relay clicks and using a stopwatch to time them and
then averaging those percentages. You would use this observed average
in place of the 75% in the calculation above.
Pls let me know if I need to be more clear!
Cheers,
Bruce
mtigges@NOSPAM.SHAW.CA on fri 23 dec 05
On Thu, Dec 22, 2005 at 11:57:33PM +0000, nsmheralds@netzero.net wrote:
> Greetings unto the list. I have access to two older Skutt kilns,
> model 1326-208, I believe. They're about 12 cu ft. each and have
> manual controls. They need to be wired. Before that, I need to
> know what they're operating costs are likely to be. (The kilns are
> owned by the local Park and Rec folks, so it's one of those
> paperwork things.) Since electricity rates vary so much, what I
> really need is an estimate on how much electricity they're likely to
> use in terms of kWh for bisque fire (I typically bisque to 1650-1700
> F), and cones 1, 6 and 8 glaze fire. The speed of my firing cycle
> will no doubt influence how much energy is used, but an average
> should be sufficient. Thanks.
I wrote a computer program awhile back which helps me manually turn
the kiln up and down according to a firing schedule ... I don't have a
computer controller for my kiln. One of the things that this program
does is compute the cost of the firing.
My kiln has 7 power levels on each circuit. So, every time I change
the power setting, I note it in the program. The program then says ...
cost = p / 7 * MkW * t * kWhp
where, p is the power level the kiln was at
t is the number of hours the kiln was at power level p
MkW is the max kW the kiln
kWhp is the price for one kWh
So, for you, to make a ballpark guess about the cost of a firing, you
have to figure two things ... how long a firing takes, and the mean
power level used for the firing.
Or, since your kilns are manually controlled, you probably know the
schedule of power changes so you can work it out yourself, for each
stage in your firing schedule.
As a best guess, when I fire to cone 6, I would say that my average
power setting is 0.75-0.8 for the whole firing, and it takes about 14
hours.
so: 0.8 * 5 * 13 * 0.06 = $3.12
0.8 is my mean setting, 5 is the max kW of my kiln, fired for 13
hours, at 6 cents per kWh ... $3.12 to fire to cone 6.
My kiln is quite inefficient, and my cost for a kWh is quite low.
Your mileage will vary.
Regards,
Mark.
Steve Van Cleave on fri 23 dec 05
Nathan,
I've got a Skutt KM-1227 that I converted from three to single phase.=20
My bisques are to ^04, and are quite long (40 hours + - 2) since I
work with thick sculptural forms. I determined the average kWh/hour
for our service drop before firing. I capture total hours of firing
and multiply this by the above average. I then subtract this value
from the total kWh recorded for the firing. My average is 110 kWh for
bisque. Don't know how useful this will be for you since my cycle is
long, but it gives you a ball park range if others on the list offer
their input.
STEVE
On 12/22/05, nsmheralds@netzero.net wrote:
> Greetings unto the list. I have access to two older Skutt kilns, model
> 1326-208, I believe. They're about 12 cu ft. each and have manual contro=
ls.
> They need to be wired. Before that, I need to know what they're operati=
ng
> costs are likely to be. (The kilns are owned by the local Park and Rec
> folks, so it's one of those paperwork things.) Since electricity rates v=
ary
> so much, what I really need is an estimate on how much electricity they'r=
e
> likely to use in terms of kWh for bisque fire (I typically bisque to
> 1650-1700 F), and cones 1, 6 and 8 glaze fire. The speed of my firing cy=
cle
> will no doubt influence how much energy is used, but an average should be
> sufficient. Thanks.
>
> Nathan Miller
> Thistillium Pottery
> Newberg, OR
>
> _________________________________________________________________________=
_____
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
steve graber on fri 23 dec 05
everybody really just wants to know the dollars.
for my southern California area, electric is $0.14 per kilowatt hour. so the 110Kw Hr example reading below is $1.54 in cost for me.
around here for businesses using lots of power, it's $0.16 per kilowatt hour. some regions are pretty cheap, my sister in law in Massachusetts says she pays $0.08 per kilowatt hour. ~ but then pays more for taxes & distribution charges...
the local electric companies will actually be friendly & answer such questions. i checked on some giant heater we have at work & got a decent answer - in dollars - that we all were looking for.
generally multiply voltage x current (amps) to get watts. multiply this times the hours of expected use (maybe just call it 24 hours). divide this by 1000 to get Kilowatt hours. multiply that by your own local rate for the cost.
see ya
steve
Steve Van Cleave wrote: Nathan,
I've got a Skutt KM-1227 that I converted from three to single phase.
My bisques are to ^04, and are quite long (40 hours + - 2) since I
work with thick sculptural forms. I determined the average kWh/hour
for our service drop before firing. I capture total hours of firing
and multiply this by the above average. I then subtract this value
from the total kWh recorded for the firing. My average is 110 kWh for
bisque. Don't know how useful this will be for you since my cycle is
long, but it gives you a ball park range if others on the list offer
their input.
STEVE
On 12/22/05, nsmheralds@netzero.net wrote:
> Greetings unto the list. I have access to two older Skutt kilns, model
> 1326-208, I believe. They're about 12 cu ft. each and have manual controls.
> They need to be wired. Before that, I need to know what they're operating
> costs are likely to be. (The kilns are owned by the local Park and Rec
> folks, so it's one of those paperwork things.) Since electricity rates vary
> so much, what I really need is an estimate on how much electricity they're
> likely to use in terms of kWh for bisque fire (I typically bisque to
> 1650-1700 F), and cones 1, 6 and 8 glaze fire. The speed of my firing cycle
> will no doubt influence how much energy is used, but an average should be
> sufficient. Thanks.
>
> Nathan Miller
> Thistillium Pottery
> Newberg, OR
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
______________________________________________________________________________
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
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Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
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