The first is the manufacturing tolerance in the NTC's nominal resistance. The second factor is the tolerance in the material constant b , which determines the variation of resistance with temperature. Manufacturers specify tolerances on both at the rated temperature. When the tolerances for a thermistor are specified in this manner, the use of the equation is implied. This is another measure of tolerance and is expressed as a temperature tolerance over a temperature range.
Interchangeability gauges how close the resistance-temperature curves of two thermistors match.
High interchangeability helps keep costs down since equipment does not need to be calibrated or adjusted for individual thermistors. Interchangeability is also a major advantage where NTC thermistors are used as cheap, disposable temperature probes, for example, in medial applications. In the next installment, I will continue exploring NTC thermistors and how to interpret the data sheets.