A special fixture for thermocouple verification and thermocouple verification method

Abstract

The invention discloses a special fixture for thermocouple verification, which includes a clamp body A and a clamp body B connected together, the clamp body A is used to connect the positive pole of the thermocouple, the clamp body B is used to connect the negative pole of the thermocouple, and the clamp body A , B are all equipped with a spring clip structure, the front end of the spring clip structure is a clip mouth, the inner cores of the clip body A, B and the clip mouth of the clip body are all made of metal material with good thermal conductivity, and the clip body A and B are contacted and connected. However, the two are insulated, and a temperature sensor is installed inside the end of the clamp body B, which is connected to the external electrical measuring equipment through the data line. The inner core metal ends of the clamp body A and B are welded with signal wires and connected to the external electrical measuring equipment , Compared with the existing verification device and verification method, the product of the invention has reasonable structural design, convenient operation and use, simple and convenient measurement process, and high measurement accuracy.

Description

technical field [0001] The invention relates to a thermocouple detection device and a method thereof, in particular to a special fixture for thermocouple verification and a thermocouple verification method. Background technique [0002] Thermocouple is the most commonly used sensor in the temperature measurement industry. Its temperature measurement principle is based on the principle of thermoelectric effect, that is, two conductors with different components are welded or spliced ​​together. A thermoelectric potential is generated in the circuit, and the temperature is measured by measuring the magnitude of the thermoelectric potential. During the use of thermocouples, due to high-temperature volatilization of thermodes, changes in grain structure, oxidation and corrosion, etc., aging and deterioration often occur, which changes the thermoelectric characteristics and causes temperature measurement errors. In order to make its temperature measurement accurate, the working t...

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Problems solved by technology

[0003] The current problems of the above test devices and methods: During the thermocouple verification process, the reference terminals of the tested thermocouple and the standard thermocouple need to be well connected with the copper wire connected to the electrical measuring equipment, and the temperature compensation of the reference terminal of the thermocouple is performed.

If a freezing point device is used as reference terminal compensation, it is usually necessary to connect multi-strand copper wires and galvanic wires by twisting. The connection method of twisting together has the following problems: 1. The wiring operation is cumbersome and the efficiency is very low.

If the couple to be detected is an armored thermocouple, it is necessary to use an additional compensation wire to lead the positive and negative poles on the flange at the rear end of the thermocouple into the freezing point bottle, which is very troublesome to operate.

2. Copper wires are easily oxidized and need to be sanded frequently to ensure good contact. As a result, the connecting wires are getting shorter and shorter

3. The thermocouple wire will break if it is often twisted

If the external temperature sensor reference terminal compensation method is used for verification, the alligator clip is usually used for connection. The connection method of the alligator clip will bring the following problems: 1. The conventional alligator clip usually cannot meet the requirements for the parasitic potential in the verification process, and the industry regulations stipulate The parasitic potential should be lower than 0.4μV, and ordinary alligator clips cannot meet the standard requirements

2. There is a deviation in the temperature compensation of the reference terminal. The main reason here is that during the working process of the thermocouple, the working terminal will transfer heat to the reference terminal, especially for a relatively short thermocouple, so the temperature of the reference terminal is actually higher than the ambient temperature. The external reference terminal sensor can only measure room temperature, so the method of using an external reference terminal is easy to operate, but the error is large

3. There are many galvanic couples in the verification process, and the temperature of their reference junctions is not the same, but usually only one external reference junction compensation is used, so using the same external reference junction compensation will also cause relatively large errors in measurement results

4. The galvanic wire of the thermocouple is usually relatively thin, which is easily affected by the fluctuation of the ambient temperature, thereby increasing the error component in the verification result

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