When testing, use the ohm gear of the multimeter (depending on the nominal resistance value to determine the gear, generally R1 gear), which can be operated in two steps: first, test at normal temperature (indoor temperature is close to 25 degree ), use alligator clips instead of test pens to clip them separately. Measure the actual resistance value of the two pins of the PTC thermistor, and compare it with the nominal resistance value. If the difference between the two is within ±2Ω, it is normal. If the actual resistance value is too different from the nominal resistance value, it means that its performance is poor or damaged. Secondly, heating test, on the basis of normal temperature test, the second step test - heating test can be carried out, a heat source (such as an electric soldering iron) is heated close to the thermistor, and the multi-function indicator is observed. It is seen that the multi-function indicator changes with the increase of temperature, which indicates that the resistance value is gradually changing (the NTC resistance value of the negative temperature coefficient thermistor will become smaller, and the PTC resistance value of the positive temperature coefficient thermistor will become larger) , When the resistance value changes to a certain value, the displayed data will gradually stabilize, indicating that the thermistor is normal. If the resistance value does not change, it indicates that its performance has deteriorated and cannot be used continuously.
Følgende punkter bør noteres under testen: (1) Rt måles av produsenten når omgivelsestemperaturen er 25 grader, så når man måler Rt med et multimeter, bør det også utføres når omgivelsestemperaturen er nær 25 grader til sikre testbarheten. pålitelighet. (2) Måleeffekten skal ikke overstige den angitte verdien for å unngå målefeil forårsaket av strømmens termiske effekt. (3) Vær oppmerksom på korrekt drift. Når du tester, må du ikke klemme termistorkroppen med hendene for å forhindre at menneskelig kroppstemperatur påvirker testen. (4) Vær forsiktig så du ikke gjør varmekilden og PTC-termistoren for nærme eller kommer i direkte kontakt med termistoren for å forhindre at den blir skåldet.
