Changzhou OSK special cable Co., LTD

Armored thermocouple in modern work is widely used, according to different uses are divided into K type thermocouple, high temperature thermocouple and so on, thermocouple has undoubtedly become one of the most commonly used temperature detection elements in industry, it has high measurement accuracy, wide measurement range, simple structure, easy to use and so on. Changzhou OSke armored thermocouple manufacturers on their verification methods for you to do the following share.1. Verification deviceThe device is mainly composed of a flat heating coil which can hold two quartz tubes at the end of the measured couple, two armoured thermocouples with the same shape as the measured couple and corresponding temperature control display output device.2. Verification methodFirstly, two calibration thermocouples are used to find out the point in the flat heating coil that makes the two calibration couples have the same thermoelectric potential, and one calibration couple is replaced by the detected couple. If other conditions remain unchanged, the quantity value of the detected couple can be determined by comparing the reading of the detected couple with that of the calibrated couple after the reading of the detected couple is stable.The verification method is to insert the two calibration thermocouples relative to each other from both ends of the heating coil, so that the hot ends of the armored thermocouple contact, change the position of the calibration thermocouple in the heating coil to make the thermoelectric potential of the two calibration thermocouples the same, and replace one of the calibration thermocouples with the measured thermocouple. The thermoelectric potential value in the stable state can be read and compared with the thermoelectric potential of the calibrated thermocouple to know the accuracy of the armored thermocouple under test.This method provides a means of laboratory verification of thermocouples, which can be tested and evaluated comprehensively at multiple temperature points.The above is the experience of Changzhou OSCO as a thermocouple manufacturer for many years to share, but also once again remind users to be sure to verify its accuracy before use, and welcome interested friends to consult our company.

The selection of compensation wire has a great influence on the accuracy of thermocouple temperature measurement, and instrument operators must be familiar with the performance and indicators of various compensation wires. Next, the main compensation wire use precautions to make a brief introduction.1. For S type thermocouple and R type thermocouple, there are two kinds of compensation wires SC and RC, both of which belong to compensation type compensation wires, and the accuracy is low in all kinds of compensation wires. The error is small in the range of 0-60 ° C, but there is a large error in the range of 100-150 ° C. If the measurement accuracy is high, the temperature of the compensation contact must be kept below 100 ° C.2, K type thermocouple compensation wire has KC type and KX type. KX is a extended-type compensation wire, the characteristic curve is linear in a wide temperature range, the error is small, but the cost is high and the resistance is large. Therefore, in the case that the use temperature is not high and the temperature measurement accuracy requirements are not too strict, the cheaper compensation type compensation wire KC type should be used.Problems to pay attention to when using compensation wires:1, all kinds of compensation wires can only be paired with the corresponding model of thermocouple, different models can not be used.2, the compensation wire has positive and negative poles. When used, the positive and negative poles of the compensation wire should not be connected incorrectly, otherwise it will not only fail to compensate, but also cause a large measurement error. It has been proved that the error caused by the wrong polarity of the compensated wire is about twice that of the uncompensated wire.3, the temperature of the thermocouple and compensation wire connection point shall not exceed the specified use temperature. Because the specified operating temperature is exceeded, the thermoelectric characteristics of the compensation wire and the thermocouple differ greatly, resulting in measurement errors.4, because the thermoelectric characteristics of the compensation wire and the thermocouple are not exactly the same, the temperature of the two contacts at the connection is required to be the same, otherwise it will cause measurement error.5, according to the different requirements of the equipped display instrument to choose the diameter of the compensation wire. For example, the compensation wire connected with the moving coil instrument can be selected with a thicker wire diameter, so that its resistance value is smaller, so that it will not exceed the external resistance value specified by the instrument.6. In order to facilitate installation, multiple strands of compensation wires can be selected, and waterproof, anti-corrosion and fireproof compensation wires can also be selected according to needs.

1, compensation wire selectionThe compensation wire must be correctly selected according to the type of thermocouple used and the occasion of use. For example, the k pair should select the compensation wire of the k pair, and then select the operating temperature range according to the use occasion.2. Connect the contactKeep the two contacts of the thermocouple terminal as close together as possible, and then keep the temperature of the two contacts similar. Make the temperature of the instrument terminal connection as consistent as possible, and where there is a fan in the instrument cabinet, the contact should be protected and do not let the fan blow directly to the contact, otherwise it will bring unnecessary trouble.3. Length of useBecause the signal of the thermocouple is very low, it is at the microvolt level, if the distance is too long, the signal will be attenuated by the lengthening of the length and the interference of strong electricity in the environment, which is enough to lead to the signal distortion of the thermocouple, resulting in inaccurate measurement and control of temperature, and temperature fluctuations will occur in serious control.According to our experience, it is usually better to use the length of the thermocouple compensation wire to control within 15 meters, if more than 15 meters, it is recommended to use a temperature transmitter to transmit signals. The temperature transmitter converts the potential value corresponding to the temperature into direct current transmission, which has strong anti-interference.4. Wiring positionCompensation wire wiring must be away from power lines and interference sources. Where crossing cannot be avoided, it is also possible to use a cross way, not parallel.5. Shield compensation wireIn order to improve the anti-interference of thermocouple wire, shielding compensation wire can be used. For the occasions with more on-site interference sources, the effect is better. However, the shielding layer must be strictly grounded, otherwise the shielding layer not only does not play a shielding role, but enhances the interference.