Seeking help regarding platinum resistance temperature measurement～
Thread Content
The resistance value of the platinum resistor at the site, as determined from a lookup table, corresponds to a temperature that is four degrees higher than the temperature calculated when the platinum resistor is connected to the transmitter. . . Even after replacing the transmitter, there is still a four-degree deviation, and this is the temperature condition at that site. . I’m currently struggling to figure out why there is this 4-degree discrepancy. When the resistance value is calculated directly at 26°C, the reading on the gauge comes out to 22°C; while for the other tubes, when the calculation is done at 56°C, the gauge shows 52°C... What’s the problem here????
After investigation, it is likely that the platinum resistor has aged, resulting in an increased resistance between the two auxiliary terminals; the resistance of a new, normal terminal is very low
Subtract the resistance between the wires from the measured resistance value, and then consult the table to get the corresponding value
This indicates that the cable resistance is approximately 1.54 ohms; however, the transmitter is usually very close to the primary meter, so such a high resistance should not occur.