Working with temperature sensors and temperature transmitters can be a complex and efficient process. In order to use both tools effectively, it's best to be educated and informed about the differences, as well as understand how they work together to measure temperature changes.
Below, we explain the difference between the two and how they relate to each other to provide accurate temperature measurements.
temperature sensor
A temperature sensor is a device that provides temperature measurement through an electrical signal. The sensors consist of two metals that create a voltage or resistance whenever they detect a change in temperature. To learn more about how temperature sensors work, click here.
Temperature sensors play an inescapable role in maintaining specific temperatures in manufacturing equipment ranging from pharmaceuticals to beer. For the production of these types of contents, the accuracy and responsiveness of temperature and temperature control are important to ensure a good final product cannot be overemphasized.
Temperature sensors come in different forms and are used in different methods of temperature management. The primary temperature sensor consists of:
Resistance Temperature Detector (RTD)
An RTD is known as a resistance thermometer and measures temperature by the resistance of the RTD element to temperature. Metals can be made of different materials including platinum, nickel or copper. However, platinum is accurate and therefore more expensive.
thermocouple
The thermocouple is a sensor with two wires made of two different metals connected at two points. The voltage between the two wires reflects the change in temperature. Although they may be slightly less accurate than RTDs, they have the widest temperature range -200°C to 1750°C and are generally more cost-effective.
Negative Temperature Coefficient (NTC) Thermistors
Thermistors exhibit precise, predictable large changes over a wide range of temperature changes. With such a large change, it means that the temperature can be reflected very quickly but very accurately. Due to their large and fast nature, NTC thermistors do need to be linearized - so some math is involved.
To simplify things, a temperature sensor does just that, it senses the temperature of whatever it needs to measure, be it a solid, liquid or gas.
Temperature Transmitters A temperature transmitter is a device that is connected to the temperature sensor to transmit signals for monitoring and control purposes.
Temperature sensors are usually RTD, thermistor or thermocouple sensors (as mentioned above) which will interface with a DCS, PLC, data logger or hardware display.
The role of the temperature transmitter is to isolate the temperature signal, filter any EMC noise, and amplify and convert the temperature sensor signal to a 4-20mA or 0-10V DC range.
4-20ma temperature transmitters are common in manufacturing because most industrial equipment used is formatted to communicate within that temperature range.
The temperature of the transmitter can be scaled inside the device to suit application needs. As far as thermometers go, 4mA represents -17.7°C – or 0 degrees Fahrenheit, while 20mA is the highest measured value, representing 37.7°C – or 100 degrees Fahrenheit.
The temperature transmitter operates by sinking current from a remote DC power source connected to the sensor input. The actual signal is sent as a change in power. To connect the temperature transmitter, only two copper wires are required.
In short, a temperature transmitter is an electronic instrument that is connected with a temperature sensor to isolate, amplify, filter noise and convert the signal from the sensor into a signal to send to the control device. It is a tool to help measure and warn of temperature changes.
So, what are the advantages of using a temperature transmitter compared to traditional measurements?
No need for AC power at remote locations when operating two-wire transmitters
Two-wire transmitters do not emit a lot of electrical noise
Temperature transmitters are cheap because wires are not expensive
Now that we can see how both devices work, what are the main differences?
Difference Between Sensor and Transmitter Compare the Difference Between Similar Terms
We know and understand the main functions of temperature sensors and temperature transmitters, so it is obvious to see the difference between the two.
The most obvious difference is that a sensor is a device that measures or senses physical temperature and converts it into measurable units of electrical current, including voltage or resistance. Whereas, a transmitter is a device connected to a sensor that converts the measured temperature into a signal so that it can be viewed, recorded and maintained.
Although they are all different tools, they all work together and play an important role in ensuring accurate temperature is measured and communicated for temperature control.
