Fault phenomena and handling methods of thermocouples

Thermocouples, due to their frequent use and lack of proper care, are prone to malfunction. For experienced operators, they can distinguish where the performance is presented and how to handle the problem by observing the malfunction of the thermocouple during the process. So, for experienced players, where should they start? Below are two types of problematic situations and their solutions:

Thermocouple malfunction scene:

1. The control screen displays a white image with the highest value of the scale for that image, and a thermocouple alarm occurs.

2. The manipulation screen shows that the two thermocouples in the furnace area tend to be larger.

Mechanism analysis: Using thermoelectric principles for measurement, compensating for the connection of wires to the system through the process, and presenting it on the screen.

Problem analysis and disposal:

1. At the beginning, review whether the on-site thermocouple has resistance and whether the resistance is in ohms. If possible, review whether the thermocouple output has a millivolt signal. If the measurement value is infinite or there is no millivolt signal, it indicates that the thermocouple has been disconnected and needs to be replaced. If the measured resistance value is relatively small or there is a millivolt output, it indicates that there is a disconnection or high resistance in the circuit. It is necessary to review the circuit and terminals to see if there is any looseness or missing terminals.

2. According to the production process requirements for furnace temperature setting, and based on the temperature measurement values of other areas, it is determined that the thermocouple that tends to be larger may experience a decrease in function due to prolonged use and aging. Therefore, it can be considered for replacement.