Simple Test Method for Thermistor in air (I)

I. Purpose:

In the case of no special NTC thermistor testing instruments, meters and measuring fixtures, but also need to measure the NTC thermistor, this method provides a simple test method, although not up to the professional level of accuracy, but can roughly measure the resistance and precision of thermistor.

Two, measuring tools and materials:

1, four-and-a-half multimeter: two.

2. Test fixture: one.

3, ± 0.1℃ thermometer: one.

4. Stainless steel crocodile clip: one pair.

Iii. Measurement methods and steps:

1, first use air conditioning to control the temperature of a room at 25± 0.1℃.

2. Place the thermometer in the room to monitor the indoor temperature.

3. Connect a pair of crocodile clips respectively to the test end of a pair of multimeter pens.

4. Clamp the two lead ends of a standard thermistor on the crocodile clip, insert the other end of the multimeter pen into the multimeter, open the multimeter and dial it to the appropriate position for resistance measurement, then the multimeter displays the resistance value of the thermistor at room temperature. (Note: precision of nominal resistance is within ±0.1%, precision of B value is ±1%)

5. Place the crocodile clip near the thermometer. The multimeter is used to monitor indoor temperature changes.

6, when the multimeter monitoring the room temperature display value is relatively stable, that is, the room temperature resistance can be tested at this time, such as the crocodile clip used to monitor the thermistor resistance value and precision of the thermistor resistance to be measured at the same time, can be compared.

7. The thermistor to be measured can be judged to be qualified according to the standard resistance value ±5% range tested at room temperature.

Four, notes:

1, indoor temperature change should be controlled within the range of 25± 1℃. (The doors and Windows must be closed during measurement to reduce air flow and avoid entering and leaving the room).

2, when the constant temperature can not reach the control precision, the same resistance precision thermistor as room temperature monitoring resistance for comparison measurement.

3. Verify the accuracy of the two multimeters before measurement, and verify the consistency of the two meters at least.

4. The thermistor to be tested should be kept at room temperature for no less than 30 minutes. If the product to be tested is powered on and used, please place it for 12 hours before testing.

5. The thermometer, monitoring thermistor and resistance to be measured should be placed in the same position indoors to ensure the accuracy of measurement.

6, when testing thermistor, the operator's hand as far as possible in thermistor to keep a certain distance, so as not to bring human temperature measurement error.

Simple Test Method for NTC Thermistor in Air (II)

I. Purpose:

In the case of no special NTC thermistor testing instruments, meters and measuring fixtures, but also need to measure the NTC thermistor, this method provides a simple test method, although not up to the professional level of accuracy, but can roughly measure the resistance and precision of thermistor.

Two, measuring tools and materials:

1, four-and-a-half multimeter: two.

2, a constant temperature oil pan: size (500×300×100) size can be customized, but not too small.

3, 0.1℃ precision thermometer.

4, stainless steel crocodile clip a pair.

5, salad oil amount (to fill the oil plate is limited).

Iii. Measurement methods and steps:

1. Fill the constant temperature oil pan with salad oil. (Note: if stainless steel plate is used, please put 3~ 5mm plastic plate on the bottom of the plate as heat insulation layer).

2. Put the thermometer horizontally into the oil pan (the thermometer should be fully immersed in the oil) with the scale up.

3. Connect a pair of crocodile clips respectively to the test end of a pair of multimeter pens.

4. Clamp the two lead ends of a standard thermistor on the crocodile clip, insert the other end of the multimeter pen into the multimeter, open the multimeter and dial it to the appropriate position for resistance measurement, then the multimeter displays the resistance value of the thermistor at room temperature. (Note: precision of nominal resistance is within ±0.1%, precision of B value is ±1%)

5, put the crocodile clip into the oil plate filled with salad oil, so that the crocodile clip and thermistor are immersed in the oil, the multimeter is used to monitor the temperature change of the oil in the oil plate.

6, when the multimeter monitoring the oil temperature display value is relatively stable, that is, the oil temperature is stable, at this time can test the constant temperature resistance in the oil, such as the crocodile clip used to monitor the thermistor resistance value and precision of the thermistor resistance to be measured at the same time, can be compared.

Four, notes:

1. The temperature change of oil in the oil pan should be controlled within the range of 25± 3℃. (The doors and Windows must be closed during measurement to reduce air flow and avoid entering and leaving the room).

2. When the constant temperature can not reach the control precision, the thermistor with the same resistance precision can be used as the oil temperature monitoring resistance for comparative measurement.

3. Verify the accuracy of the two multimeters before measurement, and verify the consistency of the two meters at least.

4. The thermistor to be measured should be at the constant temperature in the oil for no less than 2 minutes, and should be fully immersed in the oil.

5, temperature probe, monitoring thermistor, resistance to be measured should be placed in the same position in the oil plate, to ensure the accuracy of measurement.