Pt100 temperature instrument of thermocouple temperature sensor

Thermocouple temperature sensor as a temperature meter, it has three main forms: thermocouple respectively, platinum resistance and heat resistance.

thermocouple composed of two different kinds of metal wire welding, the use of thermoelectric effect to work, two different kinds of metal wire, constitute a closed loop, exist in the two different conductor temperature, electric heat generated in the both. Thus the size of a current in the loop, and this phenomenon is called thermoelectric phenomena.

platinum resistance measuring principle is different from the thermocouple measurements. Platinum resistance thermocouple sensor essentially belongs to one of the PTC thermistor. The resistivity of the metal will increase with the rising of temperature, so this feature is used to measure temperature. Thin film platinum resistor, due to the structure and so on the premise of resistance is not affected, configured with a glass casing, to protect. The current generic platinum resistance of resistance of 100 ohm ( 0 ℃) , this is the international general platinum resistance. Another PT100 thermocouple sensor adopts winding ceramic type, this method will platinum wire tapping into spiral, then in the ceramic substrate, the thermocouple sensor structure is very close, in all of the platinum resistance thermocouple sensors, the structure of the highest precision, use longer and no the phenomenon of aging, but compared with thermocouple measuring principle, reaction time is slower, so when the application is often used in food science and technology, especially the laboratory research and development.

the NTC thermistor used more widely and more economic a thermocouple temperature sensor. As a result of the mixed oxide ceramic material, has a negative temperature coefficient, it is called the cause of the NTC ( 负温度系数缩写) 。 With the rise of temperature, the resistance is reduced, this is the opposite of PT100 thermocouple sensor measuring characteristics completely.

made by thermocouple temperature sensor temperature probe types mainly have three:

1, Pierce immersion probe: used to measure the temperature of the liquid and solid, the front end of the probe is designed for needle pierced. If when using measuring probe temperature lower than the measured object, according to the principle of conservation of energy, heat will be from thermal conductivity to probe on the object to be tested; If the temperature of the measuring probe than the measured object is higher, the same heat energy from the probe to the object to be tested. This means that the heated object to be tested to heat up, temperature is measured by the object temperature after heating, the measuring conditions, probe and the ratio of medium must be taken into account, because the probe and the ratio of medium, the better, the more energy to obtain more accurate measured object, due to the energy transfer can lead to produce error in measurement. We must pay attention to the instrument is not the medium temperature, but the thermocouple temperature sensor, the measurement error can be reduced by the following way: Pierce into the depth of the 10 or 15 times the diameter of the probe; When measuring the liquid, as far as possible for the flow of the fluid can effectively reduce the error.

2, surface probe, which is used to measure the surface temperature of the object. Air temperature sensor probe and the surface using surface temperature measurement, the front end of the probe must be perpendicular to the object under test, and fully contact object to be tested. Must pay attention to is the probe of analyte and contact surface must be smooth, otherwise will affect the measurement result when measuring.

temperature probe contact methods, mainly used in the food of the temperature control in the process of sampling inspection, food, transport, flue flow center of flue gas temperature measurement, the difference in temperature measurement, electronic through the surface temperature measurement to detect when welding preheating condition, in the chemical reaction process through immersion when measuring chemical solution temperature, in the machinery manufacturing industry, measuring surface temperature of bearing and gear, to maintain and repair, etc.

3, air temperature probe, which is used to measure the air temperature, such as refrigerator, air-conditioner, air conditioning room ( Temperature) , ventilated place, Ventilation exhaust) Air probe, such as the bare thermocouple sensor, so it is easy to value is influenced by air flow, the best solution is for 2 - in air 3 ms, downstream light probe, make temperature balance and stability.