The R-T Diagram plots the Resistance – Temperature Characteristics of different PTC elements.

-          A type is set as high Curie temperature PTC element whose Tc is higher than 120℃. The slope of the R-T is not as steep because this gives a smaller calibration of resistance changes per degree temperature change.

-          Typical application of A type PTC elements: thermal sensor, over heat protectors, motor starter and high temperature heaters.

-          B type PTC elements with Tc bellow 120 ℃: the steep slope gives a higher resistance sensitivity in on-off situation.

-          Typical applications of this type PTC elements include: thermal sensors, over current protectors, delays and degaussers.