Negative temperature coefficient thermistor parameters and test methods1

Negative temperature coefficient thermistor is a kind of common sensitive element, has small volume, strong and durable, high reliability, good stability and other advantages. When we were in the use of negative temperature coefficient thermistor for negative temperature coefficient thermistor is need to master the use of knowledge, engineering to specific for everybody introduction of negative temperature coefficient thermistor parameters and testing methods, hope you can help to you.

the parameters of the negative temperature coefficient thermistor, mainly include the nominal resistance, B value range and rated power.

nominal resistance is often in the thermistor. Refers to the reference temperature is 25 ℃ when the zero power resistance, it also as a nominal resistance R25, B value range ( K reflects the higher the negative temperature coefficient thermistor heat sensitivity. Rated power refers to the thermistor in the environment temperature is 25 ℃, relative humidity is 45% ~ 80% and the atmospheric pressure is 087 ~ 107 bar under atmospheric conditions, temporary continuous load allowed by the dissipation power. ) The main parameters of the negative temperature coefficient thermistor. Nominal resistance ( KΩ) 10 ~ 15 rated power ( W) 025, B value range ( K1980 ~ 3630) Temperature coefficient ( 10 - 2℃) - The dissipative coefficient (223 ~ 409 mW℃) 5 time constant (or higher S the highest working temperature (30 or less ℃) 125.

application of negative temperature coefficient thermistor, required to test it several important parameters. In general, the sensitivity of the thermistor for temperature is high, so should not use a multimeter to measure its value. This is because the multimeter working current is bigger, through the thermistor, fever and make the resistance to change. But to confirm the thermistor can work, use multimeter can be as simple judgment. Specific as follows: the multimeter to ohm block ( Depending on the nominal resistance tests) Respectively with the beast clip instead of pens and clamp thermistor of two feet, take note of the resistance; Then knead a thermistor with the hand, observe the multimeter, will see as temperatures rise slowly and pointer will move slowly to the right, indicating resistance in gradually reduce, when reduced to a certain value, a pointer to a halt. If the environment temperature close to the body temperature, using this method is ineffective, then available iron near thermistor circuit, also can see the clock slowly moves to the right. Such, can prove the negative temperature coefficient thermistor is only good when using a multimeter to detect negative temperature coefficient thermistor, please pay attention to three points:

1, the battery must be within the multimeter is new in the near and in front of the measurement should be adjusted the ohm zero;

2, electric block due to the scale of ordinary multimeter is nonlinear, in order to reduce the error of reading method correctly or not is very important, namely when reading the line of sight is on the clock. If the dial on the mirror, whose hands and eyes to see in the mirror shadow overlap;

3, thermistor on the nominal resistance, with the multimeter reading does not necessarily equal, this is due to the nominal value is to use special instrument under the condition of 25 ℃ when measured by multimeter measurement of a certain amount of current through the thermal resistance and generate heat, and it is 25 ℃, environment temperature can't be so not prevent to produce the error.

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key words: thermal resistance, thermocouple, thermal resistance, platinum resistance, PT100, PT1000, pressure sensor and digital temperature sensor