Skutt Zone Control Kiln - Manual

6441 SE Johnson Creek Blvd., Portland, OR 97206 Phone (503) 774-6000 Fax (503) 774-7833 www.skutt.com
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KM OPERATING MANUAL
0.2.1 REV 9/18/00 0.2.1 REV 9/18/00 0.2.1 REV 9/18/00 0.2.1 REV 9/18/00 0.2.1 REV 9/18/00
ADDENDUM
(continued)
WHAT IS ZONE CONTROL
Ever since the first kiln was fired kiln makers have sought ways to distribute heat more
evenly throughout the kiln. Zone Control has been around for quite some time however until
recently the cost of the technology restricted it’s use to highly technical industrial type kilns.
Just as with automatic controllers, the cost of Zone Control technology has reached a level which
makes it affordable for studio sized kilns.
The idea of Zone Control is to use multiple thermocouples to control various sections of the
kiln. Traditionally kilns fire hottest in the center and cooler in the bottom and top. At Skutt we
balance the elements to compensate for this natural variation in temperature however the
elements are designed with the assumption that the kiln will be loaded evenly. The more mass
you place in a particular section of a kiln the cooler it will fire. For example, if you were to load
shelves of tile closely spaced in the bottom of the kiln and tall thin vases in the middle and top of
the kiln it is likely that the tile in the bottom will be under fired.
Zone Control kilns overcome this problem by placing a thermocouple in each section of the
kiln. Each thermocouple sends an independent signal back to the controller. The controller then
processes the temperature information for each section and determines whether the section is
following the program. If the section is firing cool it will send a signal to the relay which will
energize the elements in that section.
Tighter Controls
The Controller has a programmable “lag” feature so the user can determine how much the
temperature in any zone can lag behind the desired temperature of the program. The controller
senses when any section is lagging behind the desired temperature setting and keeps the control-
ler from increasing the current temperature setting (ramping) until the lagging section catches
up. Ramping is only suspended when a section is behind by more than the programmable “lag”.
A smaller “lag” will result in tighter controls between the sections but may cause a slower firing
if one section has proportionally weaker elements or the load is extremely unbalanced. The
default setting for the lag is 10 degrees F. Therefore anytime a section is more then 10 degrees
behind the current setting the controller will wait for the lagging section to catch up before
increasing the current set point. The default setting can always be reinstated by entering the
reset command.
Thermocouple Failure Control
Zone Control offers additional security through it’s three thermocouples. A thermocouple
can fail and stop the firing with a single zone controller. The Zone Control will continue firing if
one or two of the thermocouples fail during a firing. If the top or bottom thermocouple fails the
section with the failed thermocouple will fire with the middle section. If the middle thermo-
couple fails the middle section will fire the same as the top section. The Zone Control will not
start a firing with a failed thermocouple. The Zone Control will also give an error message
(Errd) if any section gets more than 100 degrees F above the set point. Thermocouples in the
wrong section, or a stuck relay can cause an Errd message.
Zone Control Kiln Addendum