Thermocouple measuring temperature circuit diagram1

Thermocouple, it is commonly used in industry temperature measuring element, plays an important role in production. Engineering today by picture form to explain the circuit diagram of thermocouple measuring temperature for better understanding and using.

1, basic circuit of measuring temperature

figure A

figure are the basic circuit of thermocouple measuring temperature, 'A', B in the figure for the thermocouple compensation wire, t0 compensation conductor for use after the temperature of the cold junction of the thermocouple, the actual when using the compensation wire terminals extends to the measuring instrument, the cold end temperature is the meter terminal temperature of the surroundings.

2, measuring multi-point temperature circuit

2

is figure 2 multiple measured temperature with the same type of thermocouple measurements respectively, multiple thermocouples Shared a display instrument, they are a temperature measuring point through multi-channel switch to switch. The multi-point temperature measurement circuit for automatic detection circuit, according to the requirements of each measuring point temperature value, only need a set of display instrument and compensation thermocouple.

3, measuring temperature circuit

graph 3

in figure 3 it is to measure the temperature difference between two points temperature measuring circuit, use two same type thermocouple reverse series, with the same compensation conductor, the connection method makes the instrument measurement is the difference between the two thermocouple produce thermoelectric emfs, therefore to measure the difference in temperature between t1 and t2.

4, measure the average temperature circuit

graph 4

average temperature is measured with a thermocouple generally adopt the method of thermocouple in parallel, as shown in figure 4. Three is the thermocouple connected in parallel, the work in the linear section of the characteristic curve, each thermocouple series larger balanced resistance R, millivolt values at the ends of the input to the instrument as the sum of three output thermocouple thermoelectric emfs E = ( E1 + E2 + E3) 3, so can reflect the average temperature of the three temperature measuring point. The average temperature of the measured area can be measured, and the instrument degree and using a thermocouple; The disadvantage is that when a thermocouple can still work normally after disconnection, can not be quickly reflected on the instrument.

5, measuring the temperature and the circuit

5

what time of the sum of the temperature is measured with a thermocouple temperature measurement circuit of several commonly used methods of the same type thermocouple synthetic series, as shown in figure 5, the sum total of the input to the instrument at the ends of the thermoelectric emfs that E = E1 + E2, E3. The advantage of this circuit is that a thermocouple wire break thermoelectric potential immediately disappears, the other a thermocouple wire break thermoelectric potential immediately fell, the instrument can be immediately reflected on, also can obtain larger thermoelectric emfs.

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