Why does the fact that using the same material, namely bimetal, result in longer life and a smaller differential in the case of the Temperature Power Sensor?
Most of the Protector Thermostats use a bimetal disk element which is made by forming the bimetal into a spherical surface.
Because the bimetal material is not a spring material, when there is a large internal stress, such as the reverse motion of the disk, the initial drawing depth gradually becomes shallow. In other words, the preset temperature shifts to the lower side. Furthermore, after tens of thousands of repeated operations, the stroke becomes smaller and sometimes there's no stroke at all.
Because the bimetal used as a flat plate in the case of the Temperature Power Sensor, there is no internal stress. In other words, even after 10 million temperature cycles, it always returns to the initial position.
Additionally, a high performance spring material (Beryllium Copper) is used for the jump movement. Furthermore, because two bimetal are used for improved sensitivity, the differential can be made smaller, from 1/2 to 1/4 that of the disk type.
