What exactly is a snap disk? Is it nothing more than a tiny circuit breaker? Do they also trip due to overheating beyond high current surges? Thank you.
Snap disk?
- Thread starter BigJohnfromCT
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Mt Bob
Minister of Fire
Temperature activated.Can be no-normally open or nc normally closed.Example-120 degrees no,closes on temp. rise,for proof of fire,turn on convection fan,etc.250 degrees nc used for stove overheating,shuts down systems.All can be self resetting,but overheat ones a lot of times are manual,have a reset button in the middle of it.High current surge would most likely just burn it up(and other things in the device/stove.
heat seeker
Minister of Fire
It's a temperature sensor. It acts as a temperature-controlled switch, so it does affect current flow as a result of temperature. As already stated by bob bare, excess current through the snap disc would just burn the contacts. It is not intended to act as a circuit breaker.
Some snap disks open above their pre-set temperature, others close above it. In addition, they can reset themselves automatically, or have a manual push-button reset.
The AE uses one to shut down the stove if it gets too hot -- it opens the circuit, cutting power to the stove. It has to be manually reset after the stove cools down.
The AE uses one to shut down the stove if it gets too hot -- it opens the circuit, cutting power to the stove. It has to be manually reset after the stove cools down.
Thanks folks. The descriptions and information was most helpful. I was under the impression that snap disks were more of a circuit breaker than a temperature activated switch. Stay warm and good burning.
To be exact, they are a switch with a bimetallic plate that is held in position at the edges to prevent expansion or contraction. This forces the metal to move in a sideways direction, (like the end of a can popping inwards or outwards when heated) pushing on contacts of the switch. A switch marked with an F is a Fan switch designed to normally be OFF and come ON when heated. A switch marked with an L is a Limit switch designed to be normally ON and go OFF when heated. After the F or L the numbers are the degrees in which the switch is calibrated to activate.
Harvey Schneider
Minister of Fire
While technically they are circuit breakers (ie they do break a circuit) they are simply a temperature activated switch.
They unfortunately are not robust and will generally fail when you can't do without.
(broken link removed to http://www.mechprod.com/blog/bid/299970/Bi-Metal-Snap-Thermal-Circuit-Breakers)
(broken image removed)
From Wiki:
Set-point thermostats[edit]
Electrical equipment that utilizes heating and cooling systems often incorporate small pop-disc thermostats which open or close at a set temperature that cannot be changed by the end-user. The disc is formed from a bi-metallic sheet, with two layers of metal that expand at different rates, and is stamped into the final bowl shape. The switch contacts are in the center and around the circumference of the bowl.
At the transition temperature, the metallic expansion stresses on the bowl cause it to suddenly "pop" and invert itself. Depending on switch contact arrangement above and below the bowl, inversion may either open or close the electric circuit.
The inverted bowl is held under tension in the inverted shape, and it takes a certain amount of temperature drop for the bi-metallic stresses to build up sufficiently in the opposite direction, causing the bowl to "unpop" back to its original shape.
They unfortunately are not robust and will generally fail when you can't do without.
(broken link removed to http://www.mechprod.com/blog/bid/299970/Bi-Metal-Snap-Thermal-Circuit-Breakers)
(broken image removed)
From Wiki:
Set-point thermostats[edit]
Electrical equipment that utilizes heating and cooling systems often incorporate small pop-disc thermostats which open or close at a set temperature that cannot be changed by the end-user. The disc is formed from a bi-metallic sheet, with two layers of metal that expand at different rates, and is stamped into the final bowl shape. The switch contacts are in the center and around the circumference of the bowl.
At the transition temperature, the metallic expansion stresses on the bowl cause it to suddenly "pop" and invert itself. Depending on switch contact arrangement above and below the bowl, inversion may either open or close the electric circuit.
The inverted bowl is held under tension in the inverted shape, and it takes a certain amount of temperature drop for the bi-metallic stresses to build up sufficiently in the opposite direction, causing the bowl to "unpop" back to its original shape.
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