The choice of thermal resistance and thermocouple temperature sensor characteristics

Thermal resistance and thermocouple temperature sensor is the most commonly used thermal components. Working principle of thermocouple temperature sensor are two different on both ends of the metal contact surface, produce different weak voltage in different temperature, the amplifier circuit to measure temperature, it is mainly used for measuring temperature. The working principle of thermal resistance temperature sensor resistance with temperature change, mainly used for measuring the temperature of the small change. When we want to measure the temperature should be how to choose the two temperature sensors?

1, the temperature measurement range: thermal resistance and thermocouple with appropriate temperature range, according to the actual temperature measuring point temperature and the temperature gradient distribution of discretionary choice sensor. In the high temperature measurement usually choose hot accidentally, chose thermal resistance at low temperature.

2, combined with site conditions: to consider the emc performance, in particular, all kinds of noise, harmonic, differential mode and common mode interference signal. When using a thermocouple temperature sensor for temperature thermoelectric power belongs to the relatively weak electrical signals, are susceptible to interference and introduction of measurement error, and heat resistance temperature sensor for current signal is susceptible to interference, and because there are three wire system and four wire system can further reduce the system error in the measurement, so the heat resistance on the premise of meet the measuring range has the advantages of strong anti-jamming performance, no thermocouple cold junction compensation problem of trouble.

in addition, the general in the temperature measurement points are the thermal resistance temperature sensor from the transmitter and the output to secondary instrument that is not afraid of long lines caused by signal attenuation, and there is no need to use high cost compensation wire, thermocouple temperature sensor requires using compensation conductor, these cases are suitable for use of thermal resistance.

of course thermal resistance of the resistance with the temperature and the nonlinear change will introduce systematic error, and the thermal resistance of thermal inertia is shown slightly bigger, will not be able to better track the change of the temperature quickly and dramatically. To avoid system error is too large, access to the resolution of the secondary instrument of shoulds not be too big.

3, heat resistance temperature sensor calibration, the calibration method is relatively simple, the calibration point only zero and 100 degrees corresponding resistance, simple calibration equipment, calibration time is short. And thermocouple temperature sensor calibration due to temperature and annealing temperature tardy, the thermocouple calibration is not only a long time, the equipment complex, and is also very strict to the environment. Therefore in the medium temperature in line with the thermal resistance under the conditions of use, should be the first to use thermal resistance temperature sensor.

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