Thermocouple temperature sensor wiring method

Pt100 temperature thermocouple sensor is a kind of platinum ( Pt) Resistance temperature thermocouple sensor, made its converts the temperature variables can transmit the standardization of the output signal, it is mainly used for industrial process measurement and control of the temperature parameters. PT100 platinum resistance thermocouple sensor has three lead, can use A, B, C ( Or black, red, yellow) To represent the three lines, three lines between a certain rule.

the traditional method is simple, but there are a lot of shortcomings. Use the generic thermocouple sensor interface chip, only need a reference resistor is not sensitive to temperature, Pt100 connected to UTI circuit, can be obtained by MCU Pt100 and reference the proportion of resistance, resistance and temperature is obtained. This method is very suitable for microprocessor-based ( MCU） System, UTI all information only through a MCU compatible signal output, so that greatly reduced the schism between modules outside wiring and coupler.

when the thermocouple sensor PT100 temperature 0 ℃ resistance is 100 Ω, resistance rate to zero. 3851Ω℃。 Because of its small resistance, high sensitivity, so the lead resistance cannot be neglected, the third line type connection can avoid the error of measurement caused by lead line resistance, PT100 platinum resistance thermocouple sensors available A, B, C, Or black, red, yellow) To represent the three lines, three lines between has the following pattern:

resistance between A and B or C temperature at around 110 euro, 0 o between B and C, B and C in the inside is straight, in principle, there is no difference between B and C. Answer the thermocouple sensor fixed on the meter terminal has three: A line pick up on the instrument by A thermocouple sensor fixed terminals. B and C on the instrument of the other two fixed terminal, B and C line location are interchangeable, but have to plug in. If indirectly by long term, in the three specifications and length of the wire to the same.

the thermal resistance of line 3 and line 4 connection: it is to use two lines, three lines, four lines, mainly make ( Optional) With the secondary instrument to decide. General display instrument with three line connection, PT100 carry out a line, the other end of the two lines, all instrument, instrument internal offset through the bridge wire resistance. General PLC for the four lines, each set out two lines, two PLC output constant current source, PLC through the two measuring the voltage on the PT100, is also in order to offset the lead resistance, four-wire highest precision, the three lines can also be, minimum two line, need to consider the specific usage accuracy requirement and cost.

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