What is a 4-20mA Transmitter?

A 4-20mA Transmitter is a type of electronic device used to convert a physical measurement (like temperature, pressure, flow, or level) into a standardised 4-20 milliamp (mA) electrical signal. This signal can then be transmitted to a control system or display for monitoring and control purposes.

Key Features:

• Standardised Range: The 4-20mA signal provides a clear and consistent range for representing the measured value. A signal of 4mA typically indicates a minimum value, while 20mA represents the maximum.
• Fault Detection: If the signal drops below 4mA, it indicates a potential fault or failure in the transmitter or its associated components.
• Noise Immunity: The 4-20mA current loop is relatively immune to electrical noise, making it suitable for industrial environments.
• Two-Wire Operation: Many 4-20mA transmitters can be powered and have their signal transmitted using just two wires, simplifying installation.

Applications:

• Industrial Process Control: Monitoring and controlling variables like temperature in furnaces, pressure in pipelines, flow rates in chemical processes, and liquid levels in tanks.
• Building Automation: Regulating HVAC systems, lighting, and other building functions based on sensor inputs.
• Data Acquisition Systems: Collecting and transmitting measurement data to computers for analysis and storage.

In summary, a 4-20mA transmitter is a versatile and reliable tool for converting physical measurements into a standardised electrical signal that can be easily used in various industrial and automation applications.