Pete Potter on tue 26 nov 02
I have a 7kw 4 cubic foot top loader running from a 240 volt, 30 amp
supply. After firing my kiln 100+ times the time taken to reach 2200
degrees F was taking as long as 16 hours. I decided to fit a new full set
of elements. The first two firings with the new elements were great,
reaching 2200 no problem in around 9 hours. Subsequent firings are now
taking approximately 14 hours with the final 50 degrees taking nearly three
hours.
I have tested the supply for voltage and elements for continuity and
resistivity and everything seems to be fine. I also contacted the element
supplier and they tell me there is no problem with the elements if I am
getting good resistivity readings.
I have now changed the contactor, all the connector blocks and virtually re-
wired the kiln but the time taken for the last 50 degrees is still three
hours and rising.
Any help would be much appreciated.
Pete
Arnold Howard on fri 29 nov 02
Pete, have you tried testing voltage under load?
Sometimes voltage drops quite a lot when the elements are powered,
but is normal when the elements are off.
Have you tried an ammeter test when the kiln is under load? Compare
that with the amps the kiln is designed to draw.
What type of kiln do you have? Is it a 240 volt kiln on a 208 volt
circuit? Some kilns are rated for both voltages. This means that
they perform very well on 240 volts, and only modestly well on 208.
Good luck!
Arnold Howard
Paragon Industries, Inc.
--- Pete Potter wrote:
> I have a 7kw 4 cubic foot top loader running from a 240 volt, 30
> amp
> supply. After firing my kiln 100+ times the time taken to reach
> 2200
> degrees F was taking as long as 16 hours. I decided to fit a new
> full set
> of elements. The first two firings with the new elements were
> great,
> reaching 2200 no problem in around 9 hours. Subsequent firings
> are now
> taking approximately 14 hours with the final 50 degrees taking
> nearly three
> hours.
> I have tested the supply for voltage and elements for continuity
> and
> resistivity and everything seems to be fine. >
> Pete
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