Views: 575 Author: Site Editor Publish Time: 2021-01-15 Origin: Site
A temperature transmitter is a device that connects to a temperature sensor to transmit the signal elsewhere for monitoring and control purposes. Typically, the temperature sensor is either an RTD(PT100 or PT1000), thermistor or thermocouple type sensor and will interface with a PLC, DCS, data logger or display hardware.
The temperature transmitter's role is to isolate the temperature signal, filter any EMC noise, amplify and convert the temperature sensor's signal to a 4-20mA or 0-10V DC range for further use.
4-20ma temperature transmitters are common in manufacturing as the majority of industrial equipment communicates via this signal range. The transmitted temperature signal can be scaled inside the temperature transmitter to accommodate the needs of the application, e.g. the 4mA can be used to represent -17.7°C (0° Fahrenheit) and the highest value in the range (20mA) can be used to represent 37.7° C (100° Fahrenheit)
Input signals types for a temperature transmitter
An RTD (Resistance Temperature Detector or Resistance Temperature Device) is one of the most prevalent temperature sensors used in industry today. Also commonly referred to as PT100, its resulting popularity is due to its accuracy and response at temperatures between -300 to + 600 ° F.
The RTD sensor comprises of a resistor that changes value with temperature. The most common RTD by far is the PT100 385. This element measures 100 Ohms @ 0 degrees C (32 °F) and 138.5 Ohms @ 100 °C (212.0 °F).
Below RTD Temperature Table (RTD Temperature Vs. Resistance Table) for reviews.
A thermocouple sensor has a pair of dissimilar metal wires joined at one end. The junction produces a low level voltage proportional to the difference in temperature between the open and closed ends.