What is a thermistor:
A thermistor is a type of sensitive element. It is divided into a positive temperature coefficient thermistor (PTC) and a negative temperature coefficient thermistor (NTC) according to the temperature coefficient. The typical characteristic of thermistors is that they are sensitive to temperature and exhibit different resistance values at different temperatures. The positive temperature coefficient thermistor (PTC) has a larger resistance value when the temperature is higher, and the negative temperature coefficient thermistor (NTC) has a lower resistance value when the temperature is higher. They belong to the same semiconductor device.
Thermistor classification:
by material: semiconductor thermistor, metal thermistor, alloy thermistor;
by temperature coefficient: positive temperature coefficient thermistor (PTC), negative temperature coefficient thermistor (NTC).
What information should be provided for the thermistor UL certification test quotation:
1. Preliminary inquiry should be provided: product picture, function description, product name, size and purpose description, difference description of each model, whether the material has been certified, etc.
2. Accurate quotation shall be provided with: product specification, description of differences among models, structure diagram and circuit schematic diagram, list of key components and BOM.
3. The quotation for testing and certification (preparation of report) shall be provided with product instructions, description of differences among models, structure diagram and circuit schematic diagram, and list of key parts.
thermistor UL certification standard:
UL 1434
1, suitable for discrete thermistor devices composed of ceramic or polymer semiconductor materials.
2. Suitable for self-heating devices, such as heaters, control devices, such as current limiters and inrush current limiters, and sensing devices.
3. Suitable for positive temperature coefficient (PTC) and negative temperature coefficient (NTC) devices.
4. Suitable for control devices, such as current limiters, not to replace current interruption devices such as fuses, but to provide overcurrent protection that meets the requirements of end-use equipment
Test items of thermistor UL certification:
surface temperature verification test | Transient current and trigger time verification test | R/T curve verification test | Withstand voltage test | Thermal aging test | Hot, cold, and humidity cycle test | Overload test | Tolerance test | Cold duty cycle test | Short circuit test | Thermal breakdown test
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