Cantilever Bimetallic Devices
Cantilever bimetallic devices, which is the technical term applied to most single element bimetallic type controls, excel at handling electrical loads up to six amps and can operate on currents from millivolts up to 240 VAC. The construction techniques vary widely for these types of thermal controls and the operating characteristics for each type can vary based on the style of construction. There are two basic types of Cantilever controls that include Creep Action and Snap Action type bimetallic controls.
Basically creep action devices get their name from the movement of the bimetallic element used in this construction type. A creep action device utilizes a single bimetal element which either will open or close an electrical circuit based on increases in temperature and or current. The bimetallic element is produced so that there is little or no temperature differential between the opening and closing point of the devices. In certain applications, this produces a narrow temperature operating range which is desirable in many application types.
Snap action devices are similar in function to creep action devices in that snap action devices will open and close an electrical circuit based on increases in either temperature and or current. The real difference is that they are produced with specially formed bimetallic elements which produce a wider temperature variation between the point where the thermal control opens and the point at which the device will close. The devices get their name from the "snapping" sound that the bimetallic element makes when it reacts to changes in temperature.