Negative temperature coefficient thermistor detection - Knowledge of electrical resistance

by:Thermistor-Mov     2020-06-22
Negative temperature coefficient thermistor testing this article mainly introduced the negative temperature coefficient thermistor ( NTC) Thermistor and positive temperature coefficient ( PTC(列车自动控制系统) , in this paper, probably about 1100 words, read the full article 11 minutes. Thermistors are divided into negative temperature coefficient ( NTC) Thermistor and positive temperature coefficient ( PTC(列车自动控制系统) Thermistor, as a sensitive element type thermistor, according to the different temperature coefficient can be divided into positive temperature coefficient thermistor ( PTC(列车自动控制系统) And negative temperature coefficient thermistor ( NTC) 。 The typical characteristic of thermistor is sensitive to temperature, different temperatures show different resistance. Positive temperature coefficient thermistor ( PTC(列车自动控制系统) Resistance when the higher the temperature, the greater the negative temperature coefficient thermistor ( NTC) When the higher the temperature, the lower the resistance value, they both belong to the semiconductor device. But it is important to note: thermistor in the import and export links do not belong to taxable items, 85. 41 of the semiconductor devices. In indoor environment testing its value first, then the hand holding the product testing, see whether its value is smaller, if change to normal, and not normal. Note: when testing to accurately measure with a special instrument. Detect the stand or fall of thermistor heating method can be used, as shown in figure 1. The multimeter resistance of two pens and connect the two lead of the thermistor, then use a hot soldering iron ( The 20 w can) To the heating thermistor ( Near the thermistor) 。 In type PTC thermistors, with temperature increase, the resistance should be increased; For the NTC thermistor, with temperature increase, the resistance should be decreased. If heated the thermistor, the resistance is not change, thermistor has been damaged. Positive temperature coefficient thermistor ( PTC(列车自动控制系统) Detection test, use multimeter R& 次; 1 block, concrete can be divided into two steps operation: 1, normal temperature test ( Indoor temperature close to 25 ℃) ; Two pens and two PTC thermistor contact pin to measure the actual value, and with the nominal value, the two differ in & plusmn; 2 Ω is normal. If the actual value and the nominal resistance difference is too large, then its performance is bad or damaged. 2, heat detection; On the basis of the normal temperature test normal, can be the second step test & ndash; Heating detection, a heat source ( Such as soldering iron) Close to the PTC thermistor for its heating, at the same time using a multimeter to monitor whether the resistance value increases with the rise of temperature and, if yes, explain thermistor is normal, if there were no changes in resistance, illustrate its performance becomes bad, can't continue to use. Be careful not to make too close or the heat source and the PTC thermistor depend on direct contact thermal resistance, to prevent to be burnt. Negative temperature coefficient thermistor ( NTC) Test 1, measuring nominal resistance Rt: NTC thermistor is measured with a multimeter method with common fixed resistance measurement method is the same, namely according to the nominal value of NTC thermistor to choose the appropriate electrical block can directly measure the actual value of Rt. But because of the NTC thermistor is sensitive to temperature, so the test should be paid attention to the following: ARt is the manufacturer when the environment temperature is 25 ℃ is measured, so when using a multimeter to measure Rt, should also be carried out in ambient temperature of 25 ℃ near the end of the, to ensure the credibility of the test. B measuring power shall not exceed the specified value, so as to avoid current measurement error due to thermal effect. C, pay attention to proper operation. Test, don't hold the thermistor body with the hand, in order to prevent the human body temperature influence on the test. 2, estimate temperature coefficient alpha t: first measured resistance Rt1 under room temperature t1, reoccupy soldering iron as a heat source, close to the thermal resistance Rt, measured resistance RT2, at the same time using a thermometer to measure the thermal resistance Rt on the surface of the average temperature t2 to calculate again. 文章/ rmdzzfwdxs。 HTML this paper label: an article on resistance thermistor: SMD resistor appearance inspection and measurement: next article alloy function and application of the SMD resistor
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