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2022-04-13 17:05:24

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What is a thermocouple?


Thermocouples are commonly used temperature measuring element in temperature measuring instruments.


Sinton Thermocouple is directly measures the temperature, converts the temperature signal into thermoelectric power signal, and then converts it into the temperature of the measured medium by an electrical instrument (secondary instrument).


The shapes of various sinton thermocouples often vary greatly according to needs, but their basic structures are roughly the same. 

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Sinton temperature sensor are usually composed of hot electrodes, insulated protective tubes, junction boxes and other main components, and are usually used together with display meters, recording meters and electronic regulators. 

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How to judge the quality of thermocouple?

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1. Visually observe whether the protective tube is corroded, penetrated, leaking, etc.


2. Measure the continuity with a multimeter. The resistance of the assembled thermocouple is generally not more than 2 ohms, and the resistance of the wire type is generally not more than 50 ohms. Generally, it can be determined that the thermocouple has been damaged when it is more than 1K.


3. Measure the resistance value with a multimeter. Resistance over 100K is bad.


4. Measure with a multimeter ohm measurement method, adjust the resistance, connect both ends, and burn it with a lighter. If the pointer of the multimeter is obviously larger or smaller, it should be good. If the pointer doesn't move, it means it's broken.

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5. Use a multimeter to measure the voltage at both ends within millivolts. If there is no voltage, it will be broken.


6. Remove the thermocouple from the input of the instrument thermocouple, and then use any wire to short-circuit the input of the instrument thermocouple. Turn on the power supply. When the digital tube at the top of the instrument shows that the value is about room temperature, it means that the internal wiring of the thermocouple is open, and the thermocouple of the same model should be replaced. If it is still in the above state, the input terminal of the instrument is damaged during transportation, and the instrument should be replaced.


7. Remove the thermocouple of the above-mentioned fault instrument, and replace it with the thermocouple connected to the similar indexing instrument that is running normally next to it. After electrifying, when the digital tube on the original fault instrument shows the temperature of the heating element, it means that the thermocouple wiring is open, so replace the thermocouple of the same model.


8. Remove the faulty thermocouple from the instrument, measure the ohm (R)*1 with a multimeter, and measure both ends of the thermocouple with two meter rods of the multimeter. If the resistance value displayed by the multimeter is very large, it means that the internal connection of the thermocouple is open. Replace the same type of thermocouple. Otherwise, there is a certain resistance value, indicating that there is something wrong with the input of the instrument, and the instrument should be replaced.

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9, According to the instrument wiring diagram wiring is correct. If the digital tube on the meter shows a negative value after the meter is powered on, it means that the thermocouples connected to the meters "+"and "-"are connected incorrectly. Just change it again.


If there's any thermocouples inquiry, welcome contact with us and we are professional with better services and high quality thermocouples.


Sinton Group mainly make kinds of electric heating elements and temperature sensor: For example , cartridge heater,hot runner coil heating element, tubular heater element, ceramic emitter, ceramic plate heating element, aluminium casting heater, mica band heater, ceramic band heating elements, Flexible ceramic heating pad, kapton heater, PI film heating elements, resistance wire, thermocouple, Pt100 etc. Also we make industrial heaters for example air duct heater, pipeline heater, oil circulation heater, drying oven etc. All of our heaters and temperature sensor can be OEM and now we have acquired CE certificate for our heating elements.

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