does the fact that using the same material, namely bimetal, result
in longer life and a smaller differential in the case of the Temperature
of the Protector
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
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.
To see the mechanical configuration, click > "What
is a Temperature Power Sensor"