Design, Manufacture and Supply of Process Instrumentation

Loop Powered Temperature Transmitters Output Connections

 

Loop Powered Temperature Transmitters Output Connections

A (4 to 20) mA loop can be used for representing a variety of engineering or process values including temperature.

It is a robust signal capable of transmission over 100s of metres and is easily connected to a multitude of control or monitoring equipment.

The temperature transmitter’s (4 to 20) mA output current will be configured to represent a range of temperature from a Pt100 probe. For example, a temperature range of (0 to 100) °C can be represented by (4 to 20) mA by the output of the temperature transmitter. This relationship between input signal and output range is liner so that:-


0°C = 4 mA

25°C = 8 mA

50°C = 12 mA

75°C = 16 mA

100°C = 20 mA

 

The output temperature range will be chosen to match the application and must also be matched to the control or monitoring system (display, PLC, etc.).

Loop powered temperature transmitter (4 to 20) mA output connections

The temperature transmitter’s output pins are connected to a supply voltage, this is normally within (10 to 30) VDC, a current of between 4 mA and 20 mA will flow in the circuit. Higher and lower conditions may be possible to indicate fault conditions. (Refer to the product data sheet for information - known as burnouts.)

A temperature transmitter connected to a control system/unit that is powering the (4 to 20) mA loop

 
 


 A temperature transmitter connected to a control system/unit with an external power supply powering the (4 to 20) mA loop.