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The calibration functions of thermostats and process control regulators are not used frequently, but their proper use can significantly improve system efficiency and product quality. In this article, Changhui introduces the basic knowledge of thermostat input calibration as well as some of its advantages, providing useful guidance for those who have never performed input calibration before, and revealing the deeper benefits it brings to the system. Why is it necessary to calibrate the thermostat? Changhui Instruments has calibrated the thermostats in the factory to ensure they achieve the precision specified in the product specifications. Factory calibration treats the thermostat as a standalone device, without taking into account all the factors of the entire system in which the controller is used. Many external factors can affect the overall accuracy of the system, such as sensor precision and positioning; in addition, the type of cable and its length can also cause errors. Through the input calibration function of the thermostat, you can eliminate these errors and achieve the desired overall system accuracy. If the thermostat is not calibrated, even a small error can have a serious impact on the quality of the output. For example, the aerospace industry has extremely high requirements for safety, and high precision is key to achieving that safety; meanwhile, the success of the manufacturing industry also depends on whether the products meet quality control standards. To obtain Nadcap (**Aviation and Defense Contracting Agency Certification**) approval, aircraft manufacturers must establish a comprehensive quality system that includes thorough procedural guidelines as well as complete records of all production batches (including data on time and temperature). To ensure the quality of the aircraft as well, manufacturers conduct regular tests on system accuracy to guarantee that the systems are properly calibrated within the allowable parameter ranges. The U.S. Food and Drug Administration also requires similar system accuracy tests in the pharmaceutical industry, whereas a narrow temperature range in the life sciences industry is key to ensuring that experiments and tests are conducted under optimal conditions. On the other hand, in some manufacturing processes, the high requirements manufacturers have regarding temperature tolerances stem not from standard specifications, but from the need to improve process efficiency. No manufacturer wants to make multiple attempts before producing qualified products, or face downtime due to poor quality from the production line; ensuring system accuracy will effectively prevent such situations from occurring. How to calibrate the input of a thermostat? In process equipment, sensors are installed as close as possible to the product, while the thermostat displays the values measured by these sensors: the sensors provide analog signals through their inputs, and the thermostat converts these analog signals into digital signals for display. When calibrating a thermostat, the value displayed on the instrument is compared with a correctly calibrated temperature measurement in order to determine the error. There are two methods for calibrating temperature sensors: one is single-point calibration, also known as zero drift calibration, and the other is two-point calibration. Single-point calibration is suitable when errors exist at both the minimum and maximum values of the range, and when the errors across the entire range exhibit a certain linear relationship. But the most accurate calibration method is still two-point calibration, at which the errors for the minimum and maximum ranges are different. When performing calibration, make sure the machine is operating within the temperature range you require. For example, if the machine normally operates within the range of 200 degrees to 400 degrees, then even though the thermostat’s calibration range is 0–800°C, you should set the minimum calibration value to 200°C and the maximum calibration value to 400°C. You should determine the error for these two points to ensure calibration is carried out within the machine’s actual operating temperature range – the machine will never operate outside this range under extreme temperatures. Zero drift or single-point calibration refers to the range by which the instrument’s reading deviates from zero when the temperature changes. The zero drift should be set at the midpoint of the operating temperature range (unless it is perfectly linear, in which case the relationship over the entire range is known and this step is not necessary). Proper thermostat calibration not only ensures that the system complies with regulatory requirements, but also brings other advantages such as reduced waste and an optimized overall control system that leads to higher productivity. Learn more about thermostats: Thermostats, AI-based PID regulators. Original source: Technical Database http://yunrun.com.cn/tech/2332.html