One of the most common electrical/electronic temperature transmitters (E.T.T) is made by Rosemount (Model 444). This is used as an example of a typical instrument.
The Rosemount Model 444 consists of :
The type of sensor depends on the range and application; eg:
- Thermocouple – Type E, J, K, R, S, T.
- RTD – Copper (I0 ê), Nickel (120 ê) and PT 100 ê with 2, 3 or 4 wire connections.
This unit has two boards. A RANGE board, depending on the sensor in use and an AMPLIFIER / OUTPUT board which produces the standard 4 – 20mA signal for the control room.
Local Temperature Indicator
This unit may or not be included. It provides either a moving coil type display or a digital display. It gives an on-site temperature reading to the operator.