High Temp Limit
High Temp Limit
(OP)
I am currently searching for a limit switch that can handle 420 dg/F. We have a oven and trays slide in, the limits are mounted at the exit do tell us if all trays are inside. They are currently outside of the oven since the trays protrude in the front in back.
ex ____------___LIMIT The solid line is the tray the
dotted is the oven. The word limit is where the limit is mounted. Any ideas?
ex ____------___LIMIT The solid line is the tray the
dotted is the oven. The word limit is where the limit is mounted. Any ideas?





RE: High Temp Limit
I have used coils embedded in a ceramic clay (talk to a potter near you). The coils have a rather low inductance when there is no iron close to them. Iron increases inductance and that can be sensed in several ways. The coils are in effect the same thing as you use in a metal detector so they will akso work with non-ferrous metals. But then it is not the inductance that changes. Instead, the losses go up when metal comes close (Q factor goes down).
If the oven can accept an extra air flow, then pressurized air can easily sense a moving vane that is actuated by the trays. A fork configuration (air nozzle in one leg and sensing nozzle in the other leg, vane goes in between the legs) works very well and is very reliable. I used 100 PSI and solid state pressure sensors (monted separately outside the oven, of course
You have probably already thought of the obvious solution: let the trays actuate an arm that turns a shaft and monitor the turning outside the oven. Some ovens do not like having holes in them so it is not always possible to use this simple technique.
Good luck!
RE: High Temp Limit
RE: High Temp Limit
RE: High Temp Limit
use magnet with high enough Curie point !!
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