Questions about thermal resistors
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I have a question for everyone: One of our company’s high-pressure boilers uses a thermistor to measure the exhaust gas temperature (with no temperature transmitter connected). The temperature reading is always on the low side (the thermistor itself is in good condition), and this issue is more noticeable when the weather conditions change. The signal from the thermistor goes through an amplifier before being displayed on a digital meter, and from there it is recorded by a paperless recorder. I would appreciate some advice from those who are more experienced in this area???:)
I have a question for everyone: In my company’s high-pressure boiler, the amounts of coal used, the flow rate of feedwater, and the flow rate of main steam do not correspond to each other; the flow rate of feedwater is greater than that of main steam. Could someone please tell me what the reason for this is???: Thank you
Measure the resistance value on-site to see if it matches the actual temperature Is your thermistor two-wire or three-wire? If it’s two-wire, the reading will be on the low side; poor contact can also cause a low reading
It is normal for the water supply volume to be greater than the steam volume, as there is some loss of water in the boiler. If this difference is too large, it indicates a problem with the flow meter’s measurement
Thermistor wiring generally uses a three-wire or four-wire system; if a two-wire system is used, it will be greatly affected by the ambient temperature.
I think the poor contact issue is not due to a low value, but rather a high one; after all, poor contact increases the resistance, which in turn causes the displayed temperature to rise. Also, I think when the ambient temperature drops, it’s necessary to consider the possibility of condensation forming inside the wiring box of the thermal resistor, which could result in a lower measured resistance and thus a lower displayed temperature.
Reply to floor 1: The temperature is on the low side; it’s advisable to check whether the insertion depth of the resistor meets the requirements for accurate measurement. A three-wire resistor should not be affected by ambient temperature. In fact, the three-wire configuration is mainly used to address issues related to line resistance, and environmental changes have only a minimal impact on line resistance. Additionally, check the casing for any leaks; if moisture enters, the insulation quality decreases, which may result in a lower resistance value. Second floor: There could be issues with both the water flow rate and the steam flow rate. It is possible to first determine which of these is more likely to be the problem by considering other parameters. Based on the description, checking the steam flow rate first seems a good option. It should be noted whether temperature and pressure corrections need to be applied to the flow rates
The line resistance is too high: hug:
If there is no moisture inside the thermistor sleeve, and if the wiring terminals are not corroded, it is recommended to add a temperature sensor on-site and use a 4–20mA signal for transmission, which will yield better results.
“The poster said, “The temperature reading is always low.” I wonder where it’s low If the measured resistance value of the thermistor is lower than the actual temperature, it is related to factors such as the insertion depth of the thermistor ； If the digital display shows a low value, it is related to factors such as the wiring method (two-wire system, three-wire system) ； If the data recorded by the paperless recorder is low, it is related to the settings of the digital display transmitter and the input settings of the recorder.