The uncertainty of temperature changes in the setting of bimetallic thermometers

The uncertainty of temperature changes in the setting of bimetallic thermometers

Electric contact bimetallic thermometer is a bimetallic thermometer equipped with an electrical contact device, which has automatic control and alarm functions. In order to ensure the accuracy of value transmission, a measurement system including a standard platinum resistance thermometer, a standard constant temperature bath, and a signal on/off measurement circuit was constructed to calibrate the set point error of the bimetallic thermometer with a measurement range of 0~150 ℃ and a division value of 2.0 ℃, and to complete the uncertainty analysis of the measurement results. The response time of the thermometer and the rate of temperature change in the constant temperature bath can affect the measurement results. By building a measurement system, the set point error of the bimetallic thermometer with electrical contacts is measured, and the uncertainty of the measurement results is analyzed and evaluated.

(1) Measurement and uncertainty evaluation of set point errors

In order to calibrate the set point error of the bimetallic thermometer with electrical contacts, a second-class standard platinum resistance thermometer is used as the standard, and supporting equipment and calibration objects are selected. The parameters are as follows:

Measurement standard: Second class standard platinum resistance thermometer, -200 ℃~419.527 ℃; 2) Constant temperature equipment: portable constant temperature oil tank, temperature range of 30 ℃~200 ℃. Temperature control rate can be manually adjusted;

Verified object: Electric contact bimetallic thermometer, measuring range from 0 to 150 ℃, division value of 2.0 ℃, allowable set point error of ± 2.25 ℃, calibration point of 100 ℃.

(2) Measurement of metrological characteristics of electrical contacts

Place the standard platinum resistance thermometer and the electrical contact bimetallic thermometer in the constant temperature bath, and connect the electrical contact bimetallic thermometer to the on/off signal circuit. Raise the temperature of the constant temperature bath to near the set point, and after reaching a stable state, slowly increase the temperature of the constant temperature bath at a rate not exceeding 1 ℃/min. At the moment when the contact point undergoes a closed switching action, record the value t of the standard thermometer as the upper switching value; Using the same method and temperature control rate to control the temperature of the constant temperature bath, record the reading of the standard thermometer at the moment when the contact point undergoes a disconnection and switching action.

(3) Regularly share maintenance experience and conduct safety training and education

The stable operation of the power system is related to the development of various industries. Therefore, power enterprises should continuously improve the maintenance management system and ensure that the management system can be practically applied in maintenance work, avoiding it from being superficial. It is suggested that relevant management leaders should regularly hold meetings and activities such as experience sharing meetings for maintenance operations. Through communication and sharing, enhance the comprehensive ability level of maintenance technicians and enhance their ability to prevent dangerous points during maintenance. In the process of sharing experiences, it is necessary to clarify the sharing theme. At the same time, it is necessary to ensure that maintenance technicians are truly aware of the seriousness of safety issues, strengthen their technical ability to avoid dangerous points, and efficiently and accurately complete maintenance work. Finally, it is necessary to strengthen the cultivation of management talents.

In summary, whether power companies can strengthen the operation and maintenance of facilities and equipment, improve the safety and stability of equipment operation, is of great significance for strengthening the development of China's power industry. During the operation of power equipment, maintenance and repair work must be carried out regularly according to corresponding requirements, and the professional level of maintenance personnel must be strengthened in a targeted manner. For various hazardous points in maintenance operations, relevant management personnel must strengthen the training and education of technical workers. By cultivating awareness of safety precautions and improving the level of hazard elimination, we can enhance the overall ability of control and make positive contributions to the development of China's power industry.