The basic controller kit ships with a single SSR with 45 to 50 ampere current rating
very similar to the switch you see mounted on a heatsink on the right. This is the
basic part that is useful for a large majority of regular kilns.
Read about kiln switch requirements to find out more about what you need to run your
kiln.
Always remember to Heat Sink your switch. The heatsink size required varies directly with the amount of
current drawn by your kiln. Take a look at End Users Setups to see some good examples of where
the heatsink as been integrated into the packaging as well as other methods.
If you have a very large kiln that requires more than 40 amps you should
think about putting together a heavier duty power control switch. The
first option is to go to a higher current rating SSR in the same package.
They occassionally show up on ebay however not so often. Another option
is if you have several separate coils in your kiln you can use a separate
SSR on each heating coil. This is inconvenient however because you need
to use a separate plug for each if you make a portable setup. One option
choose early on was to use a set of back to back SCR's. This is
essentially what is in one of the SSR bricks in the upper right hand
picture. However these were industrial power controller surplus that are
extremely heavy duty. The SCR pair shown on the left are probably good
for in excess of 150 amps. The good news on something like this is that
if you watch carefully you can pick them up on the surplus market very cheaply. The picture on the
right shows my first switch box. It was made out of a surplus motor controller. It never even gets
warm to the touch in operation.
The next picture on the right shows the interface circuit required to
operate a set of back to back SCR's that you pick up on the surplus
market. Its opto-coupled so there is no voltage punches that snap
back into the driving circuit. Its the same board you see mounted
in the large switch pictured immediately above it.
