Common fault handling methods for temperature detection instruments
Temperature measuring instruments commonly used in the industry are divided into two categories: non-contact temperature measuring instruments (eg, radiant, infrared). Contact temperature measuring instruments (such as: expansion, pressure, thermocouple, thermal resistance). Industrial RTD temperature measurement systems are generally composed of industrial thermal resistance, connecting wires and display instruments. The industrial thermal resistance and the display instrument must have the same index number. In order to eliminate the influence of the change of the resistance of the connecting wire on the temperature measurement, the three-wire connection method must be adopted. Common causes of failure of industrial thermal resistance and treatment methods: A common fault in industrial RTDs is industrial RTD disconnection and short circuit. Generally, the open circuit is more common because the thermal resistance wire is thinner. Open circuit and short circuit are easy to judge. You can use the “×1Ω†file of the multimeter. If the measured resistance is less than R0, there may be a short circuit. If the multimeter indicates infinity, you can judge that the resistor is open. The short circuit of the resistor body is generally easier to handle, as long as it does not affect the length and thickness of the resistance wire, find the short circuit to blow dry, and strengthen the insulation. Resistor body breaking repair must change the length of the resistance wire and affect the resistance value. For this reason, it is better to replace the new resistor body. If welding repair is used, it must be verified after welding to be used. The common faults and treatment methods of the RTD temperature measurement system are as follows: Fault phenomenon possible reason Approach The display indicator indicates that the value is lower than the actual value or the indication is unstable. There are metal chips and dust in the protection tube, dirt between the terminals and short circuit of the thermal resistance (water accumulation, etc.) Remove metal chips, clean dust, water droplets, etc., find short-circuit points, strengthen insulation, etc. Display meter indicates infinity Industrial thermal resistance or lead wire disconnection and loose terminals Replace the resistor body, or solder and tighten the terminal block screws, etc. Display meter indicates negative value The display instrument and the thermal resistance wiring are wrong, or the thermal resistance has a short circuit. Correct the wiring, or find the short circuit, strengthen the insulation Resistance and temperature have changed Thermal resistance wire material is corroded and deteriorated Replace the resistor body (thermal resistance) I. Industrial thermocouple Industrial thermocouples weld two conductors or semiconductors A and B of different materials to form a closed loop. When there is a temperature difference between the two solder joints 1 and 2 of conductors A and B, a thermoelectric potential is generated between the two. Therefore, a certain amount of current is formed in the loop, which is called a thermoelectric effect. Industrial thermocouples work on this principle. Fault phenomenon possible reason Approach The thermoelectric potential is smaller than the actual value (the display meter indicates a low value) Thermal electrode short circuit Find out the cause of the short circuit. If it is caused by moisture, it needs to be dried. If the insulator is damaged, replace the insulator; clean the dust; The thermoelectric potential is smaller than the actual value (the display meter indicates a low value) Industrial thermocouple thermal electrode deterioration If the length allows, cut the metamorphic section and re-weld, or replace the new thermocouple The thermoelectric potential is smaller than the actual value (the display meter indicates a low value) Compensation wire is reversed with industrial thermocouple polarity Reconnect correctly The thermoelectric potential is smaller than the actual value (the display meter indicates a low value) Compensation wires are not compatible with industrial thermocouples Replace the matching compensation wire The thermoelectric potential is smaller than the actual value (the display meter indicates a low value) Industrial thermocouples are not properly installed or the insertion depth does not meet the requirements Reinstall as required The thermoelectric potential is smaller than the actual value (the display meter indicates a low value) Industrial thermocouple cold junction temperature compensation does not meet the requirements Adjusting the cold end compensator The thermoelectric potential is larger than the actual value (the display meter indicates a high value) Industrial thermocouples do not match display instruments Industrial thermocouples or display instruments to match The thermoelectric potential is larger than the actual value (the display meter indicates a high value) Compensation wires are not compatible with industrial thermocouples Replace the matching compensation wire The thermoelectric potential is larger than the actual value (the display meter indicates a high value) DC interference signal enters Eliminate DC interference The thermoelectric potential is larger than the actual value (the display meter indicates a high value) Thermoelectric output is unstable Industrial thermocouple terminal is in poor contact with the hot electrode. Tighten the terminal screws. The thermoelectric potential is larger than the actual value (the display meter indicates a high value) Industrial thermocouples measure line insulation damage, causing intermittent short circuit or grounding Find the point of failure and repair the insulation The thermoelectric potential is larger than the actual value (the display meter indicates a high value) Industrial thermocouples are not installed securely or externally Fasten industrial thermocouples to eliminate vibration or take shock absorption measures The thermoelectric potential is larger than the actual value (the display meter indicates a high value) The hot electrode will be broken Repair or replace industrial thermocouples The thermoelectric potential is larger than the actual value (the display meter indicates a high value) External interference (AC leakage, electromagnetic induction, etc. Detect interference sources and take shielding measures Large thermal potential error Hot electrode deterioration Replace the hot electrode Large thermal potential error Industrial thermocouples are not properly installed Change the installation location Large thermal potential error Protection tube surface area gray Clear the dust 1.Pressure control system Industrial Electric Steam Generator,Automatic Electric Steam Generator,Small Electric Steam Generator,Vertical Electric Steam Generator Henan Yuanda Boiler Co., Ltd. , https://www.industrysboiler.com
Since industrial thermal resistance and industrial thermocouples are widely used, they are mostly used in automatic interlock control systems. Here, the common fault handling methods for temperature detection instruments in use are introduced below.
I. Industrial Thermal Resistance Industrial thermal resistance is based on the fact that the resistance value of metal increases with increasing temperature to measure temperature. Zui is commonly made of metal platinum and copper, with index numbers Pt100, Pt10, Pt50 (temperature range -200 ~ 850 °C), Cu50, Cu100 (temperature range -50 ~ 150 °C).
Industrial thermocouple common faults and treatment methods
Compensating for short-circuit between wires: finding the short-circuit point, strengthening the insulation or replacing the compensation wire
Imported pressure controller circuit, high design stability, high accuracy of red flag pressure gauge, accurate display
2. Thicken stainless steel casing
304 thicken stainless steel shell, using special painting process, the shell is beautiful and durable, can be customized into food grade stainless steel
3.High temperature and high pressure water pump
The high-pressure vortex water pump of the iron body has good corrosion resistance and good passability, and the residual heat of the exhaust gas can be recovered by about 20%.
4.stainless steel heating tube
Wall thickness 1 mm, stamped and sealed, non-ordinary product welding, no leakage, no expansion and long service life
5.Brass liquid level float
Natural magnet copper level controller, anti-oxidation, anti-corrosion, prolongs service life, suitable for multi-water use
6.Stainless steel mechanical float
Stainless steel mechanical float ball has good corrosion resistance, and the ball has a threaded port, which can be replaced and repaired easily.