Thermocouple interference measurement error caused by several reasons

Thermocouple is in the process of use will be disturbed, the reason has two aspects, but on the whole can be divided into two broad categories, ac and dc interference ( The commonly used anti-jamming measures) The reason and solution and how?

a, communication interference

can be divided into the line between ac interference and the interference. Line to line interference refers to the outside world, under the influence of thermocouple ( Compensation conductor) The output will appear between the ac voltage. This kind of interference is also known as lateral, common mode and common mode interference. In general, interference between line voltage can achieve a few millivolts or even dozens of millivolt. Of interference is pointed out that thermocouple (now Or compensation conductor) Two outputs in the end, the ac voltage to the ground is called the interfering voltage. This kind of interference is also known as the longitudinal, series mode or string of state interference. In general, the disturbance voltage can achieve a few volts even more than 100 volts.

ac interference sources are mainly the following:

1, the main source of electromagnetic induction is the line between interference.

2, heat leakage effect.

3, the high pressure electric field interference.

4, current interference.

5, chao leakage effect.

6, on the charged body temperature also can introduce ac interference.

2, tributary interference

in the thermocouple measurement circuit, while additional tributaries, is the dc interference. Serious when, makes the measuring instrument can't work normally.

tributary of interference source has the following kinds:

1, attached to the heating electric potential.

2, the chemical potential.

3, thermocouple, when in contact with dc power leakage current will generate interference by measuring circuit of voltage.