What is the difference between a thermal resistor and a temperature transmitter?
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What is the difference between a three-wire thermistor and a two-wire temperature transmitter? Are there any differences in accuracy and conduction rate? Please, expert, provide a detailed explanation
A thermoresistor is a sensing element that converts temperature signals into changes in resistance, while a temperature transmitter converts that resistance into 4-20mA signals.
The difference is that the temperature control is better but more expensive. Thermal resistors are cheap. The principle is the same.
The thermal resistor can be connected directly to the DCS; a card with resistor input should be used. The temperature transmitter also requires a thermal resistor in order to transmit the temperature signal to the DCS; a card with 4–20mA input should be used. As for accuracy and transfer rate, there shouldn’t be a significant difference. Another type is the integrated temperature element, in which a temperature sensor is directly mounted on the thermal resistor for on-site use. However, when using such integrated elements, it should be noted that they are not suitable for installation outdoors in cold winter conditions, as this can affect the accuracy of the temperature measurement.
As already explained clearly earlier, I’ll repeat it: there are two components. One makes use of the principle that the resistance changes with temperature in order to detect temperature, while the other is used to process and transmit signals.
The thermoresistor is the measuring element, while the transmitter is the conversion unit; they serve different purposes； The characteristic of a thermal resistor is that its resistance changes with temperature; a transmitter, on the other hand, converts the resistance signal from the thermal resistor into a corresponding current signal for output, and their working principles are different. Thermoresistors, transmitters, and display instruments work together to form a temperature measurement system. The accuracy of the system is the result of the combined accuracy of its individual components; to achieve accurate measurements, it is necessary to choose components with high accuracy that are also compatible with each other. As for the transmission speed, it depends on the measurement units you choose. It’s like mobile phones: there are models with dozens, hundreds, thousands, or even tens of thousands of such units, but they all have the basic calling functions; it depends on what you choose......
It's mainly the Chen Ben issue, as well as the security issue. Thermal resistors have a relatively low cost and lower precision (compared to transmitters), and are used when only temperature recording is required. Our factory has many storage tanks and reaction vessels, all of which use platinum resistors for temperature measurement; the readings are displayed on the instrument panels in the workshop, which serves as an on-site display. Operators record the temperatures at regular intervals during each shift, as long as the temperatures remain within normal ranges. Transmitters are generally located in the control room, where the readings can be viewed directly; they offer relatively high precision, and the input signal is 4-20mA (which is the standard range). Actually, there’s no difference; a transmitter is essentially like a template attached to the platinum resistor, which converts the resistance signal into a current signal. Also, generally platinum resistors are used for display, while transmitters are used for control
Bro, could you advise me on any temperature measurement devices that aren’t expensive but still offer high precision? I’d like to gain some knowledge so I can impress my boss
Thermistor: It is a primary temperature sensing element that can convert temperature changes into changes in resistance signals; commonly used thermistors include those with ratings such as Pt100 and Cu50. Temperature transmitter: It can convert the resistance or thermoelectromotive force signal from the primary sensing element (thermal resistor or thermocouple) into a standard 4-20mA signal ； It is generally divided into: split-type and integrated-type (integrated with a thermal resistor or thermocouple).
This is considered from two aspects: first, the cost. If the distance is large, using a three-wire or four-wire connection for the thermistor results in very long wires and a high number of them, which increases costs. Second, there is the issue of accuracy. Although three-wire and four-wire connections can theoretically reduce or eliminate wire resistance, it is necessary for the resistance values of the wires to be identical, which is hardly possible. Therefore, using a temperature transmitter can solve this problem.
Why is temperature variation greatly affected by the ambient temperature?