The use of resistance temperature sensor information

Resistance temperature sensor is a kind of common measuring instruments, in many areas of a certain application. Inductive temperature sensor in the process of using a lot of problems to the attention of users, if improper use will not only cause the measured value is not accurate, and could be the cause of the damage, the project is to introduce specific resistance temperature sensor use requirement.

( 1) Measured value must be current, but current and can make the resistance heating, increased resistance. In order to avoid the error due to this factor is too large, should as far as possible with a small current through the resistor. Of course, the current is too small so that the resistance of voltage drop too small, and difficult to measure. It is generally believed by resistance of current shoulds not be more than 6 ma, as this is the thermal resistance at 850 ℃ of Pt100 resistance 390 Ω, the heating power only 14 mw, not cause significant error.

( 2) Use a bridge to measure the resistance when the output of the bridge diagonal common-mode voltage. If the power negative end of the bridge as the ground, the two output wires of the bridge voltage are in on the earth, and the differential mode voltage between the two wires to reflect the unbalanced degree. For the electronic circuit design is put forward certain requirements, or docking sites have requirements.

( 3) When using a potentiometer measured resistance, if multiple thermal resistance common constant-current source also has the common mode voltage. Multiple thermal resistance with four wire connection, the current line can be in series, the constant-current power supply, by the same after the two voltage line-to-line bei respectively of the potentiometer switch to the on the heat resistance, can multipoint circuit testing. But its two online common-mode voltage, voltage and common-mode voltage value is not.

( 4) Index number of same series thermal resistance can be more average temperature measurement. At this time is to use two wire connection, the serial number of thermal resistance, the more general RO. Thermal resistance is not suffer from the parallel case, because there is no practical significance. And so on, if connect to the computer interface must pay attention to this feature.

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