An unlimited switch , simmerstat , energy regulator or unlimited controller is a type of switch that allows variable power output from electric heating element stove. This is called "unlimited" because its average output is much more variable than limited to some activated level. It uses a bi-metal stripe conductive connection across a disconnected terminal with an increase in temperature. As the current passes through the bimetal connection, the current will heat up and damage, disconnecting and turning off the power. After a short time, the bimetal will cool and reconnect. Therefore, the unlimited switch varies the average power delivered to the device by oscillating rapidly between and turning off the state. They can be used for situations that are not sensitive to such changes, such as resistive heating elements in electric stoves and kilns.
Disadvantages of high-speed mechanical displacements include erosion of switch contacts by arcs and generation of radio frequency interference and general nonconformities to handle high power and inductive loads.
This can be regarded as a very slow pulse width modulator. Although similar devices are in operation for bimetal switching thermostats, the device does not really feel the temperature of "burner" to be controlled, but uses very small heating time of electric heating elements as analog.
A cam turn/cam adjustment is usually used to power-light the electricity to "burner" and also set the desired heating level.
Inside the device, very small electric heating elements heat up the bimetallic. After some time, the bimetallic strip bends to open a set of switch contacts, thus disrupting the electric current to the heating element. At the same time, another (stronger) set of spring switch contacts, mounted in parallel with the first, is also open, cutting heavy currents to the "burner". Both the small heating element and the "burner" are now beginning to cool. At some point the bimetal strip will be sufficiently straight to trigger both sets of contact switches to close, thus causing both small heating elements and "burner" to restart the above warming cycle.
Rotating the play button/cam setting further increases the pre-load on the trigger mechanism. As a result, it takes longer for bimetal strips to warp enough to trigger the "cut-out" electricity described above. Thus the "burner" becomes hotter.
Video Infinite switch
See also
- Bimetal thermostat
- Relaxation oscillator
- Dimmers
Maps Infinite switch
References
- http://www.partselect.com/range-stove-oven Infinite-Switch-Testing repair.htm
Source of the article : Wikipedia
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