Thermocouple compensation wire type and function1

Thermocouple temperature measurement used, it is necessary to maintain a constant temperature of the reference junction of the thermocouple, the introduction of measurement error in measuring temperature, otherwise will be a big variable, will affect the accuracy of the temperature measurement. But, in the field use the thermocouple reference end often near the high temperature heat source, the thermocouple reference end is affected by the heat source cannot be stable, so must be moved to the temperature of the reference junction of the thermocouple is relatively stable places; Compensation conductor with the same metal as the thermocouple materials, or in the specified temperature range ( Generally 0 ~ 100 ℃) The thermoelectric properties ( Heat up the electricity) Same as the adaptor by the thermocouple, and is easy to get cheap base metal materials, can prolong the effect of thermocouple in the temperature measurement or as a thermocouple and instrument ( Such as electronic potentiometer) The connection of the wires. So, thermocouple when use to connect the thermocouple compensation wire. But it does not eliminate the reference junction is not zero, so that in use or the reference should be revised to 0 ℃ temperature.

2, while using compensation conductor must pay attention to the following:

1. Compensating conductor only with matching type of thermocouples, which is said by all kinds of thermocouple and supporting the use of compensation wire, in the specified temperature ( If 0 ~ 100 ℃) Line heating up the electric power must be consistent.

2. Compensation conductor in connection with thermocouple instruments, two pairs of points to the same temperature, and is the cathode can't wrong. Compensation conductor should be equivalent to a team in a certain temperature ( 0～100℃) Within the scope of the thermocouple, so its current and flow to the cathode by the reference from the positive side, so connected to the thermocouple, the positive can thermocouple of the compensating conductor of the anode, cathode were negative of thermocouple. Such as the polarity inside out, not only lose the function of the compensating conductor, it will offset part of the thermocouple thermal power, the instrument of temperature indicating on the low side.

3. Compensation conductor and the thermocouple connection point temperature shall not exceed the specified temperature range.

4. Want to choose according to the different requirements of instrument for compensating lead wire diameter. Such as connected to the moving coil meter compensating lead wires can be made with thicker wire diameter, the resistance is smaller, so as not to affect the external resistance meter.

5. Lines long thermocouple and can be used more shares and coarser compensating lead wires, in order to facilitate installation and installation.

3, compensation conductor should be due to the core alloy material divided into extension model and compensation model of two kinds:

extended type compensation conductor:

have NX ( Nickel chromium silicon - Nickel silicon magnesium) 、KX( Nickel chrome 10 - Nickel silicon 3) 、EX( Nickel chrome 10 - Copper and nickel 45) 、JX( Iron - Copper and nickel 45) 、TX( Copper - Copper and nickel 45) 。

compensation type compensation conductor:

with SC and RC ( Copper - Copper and nickel 0. 6) 、KC( Copper - Copper and nickel 40) 、NC( Iron - Copper and nickel) And so on.

4, using expanded or compensation model the timing of the compensating conductor:

extended type:

cold junction compensation wires environment greater than 100 degrees or less than zero, in order to measure the accuracy of, only choose expanded compensation wire, but the price is more expensive.

compensation type:

the cheap, but the cold end temperature should be relatively stable.

5, compensation conductor must possess the characteristics of the:

1. Thermoelectric properties stability, good electrical insulating performance, long service life.

2. Soft, bending performance good, easy to use.

3. Cladding material is stable and reliable, has certain resistant and cold resistant performance.