Thermistors are temperature dependent resistors ant “PTC” stands for positive Temperature Coefficient of resistance. Ceramic PTC thermistor is a functional semiconductor that exhibits a highly positive temperature coefficient with the rise of tem perature hits Curie Point (Tc) initially: the resistance goes down as temperature rises.Then, its resistance increases rapidly past a refere-nce temperature (or Curie temperature) and this is what we call the “PTC domino affect”Using different temperature coefficients.we can make differernt PTC for varies heater sensitive ceramics for differern applications. Due to the PTC thermistor is the most energy saving and safe componert, it is widely uesd in many household electrical appliances , electric power facilities, and electronic produ-cts.In general, aplplicantions using PTC thermistor can be categorized according to three unique characteristics: resistance-temperat-ure(R/T), current-time(I/T)and current-voltage(I/T)characteristics.

      he R-T diagram plots the Resistance/Temperature char acteri-stics of different PTC pelles.A Category is set as the high curie tempe-rature PTC pellets where(Tc)is larger than120℃The slope of the(R/T) is not as steep because this gives a smallercalibration of resistance changes per degree of temperature change. The use of A category characteristicsis suttable for thermal sensor, over-heat protectors,motot stator and high heat generation heaters. Qhereas, in the B category, those withcurie point below 120℃, the Steep slope gives a higher resistance, sensitivity in a onoff situation, making them ideal for switching purposee.g. Thermal sensors ,overcurrent protectors,delays and degaussors.

       Turrent for a much shortet periond of time time.The typical application ohe current Time characteristics shows the relationship between the Current and the time under the operaton in rated voltage , the higher the volgate,a higher peak cf curren t-Time characteristics PTC used in degaussor,motor stator and delays.

      Volgate-Current characteristiscs is usually named after V-A character-istics.The V-C diagram is taken at steady state current(when current meas-ured becomes steady after some time from switched on)in still air 25℃ am-bient condition. On a standard ambient/heat dissipationo environment the PTC's steady surface temperature(Ts) is practically the same and the power(wattage)within a small variance even if different voltages are used.This gives self-heating PTCthe advantage of dual of multi-voltage usage in different countries of different voltage.