Search results
Results From The WOW.Com Content Network
4-20 mA Current Loops Overview. The 4-20 mA current loop is the prevailing process control signal in many industries. It is an ideal method of transferring process information because current does not change as it travels from transmitter to receiver. It is also much simpler and cost effective.
Current Loop System. The DC power supply provides the power to the system. The transducer regulates the flow of current through the wires at 4 to 20 mA, where 4 mA represents a live zero and 20 mA represents the maximum signal. A 0 mA signal signifies a break in the loop.
A major application of current loops is the industry de facto standard 4–20 mA current loop for process control applications, where they are extensively used to carry signals from process instrumentation to proportional–integral–derivative (PID) controllers, supervisory control and data acquisition (SCADA) systems, and programmable logic ...
The 4-20 mA current loop has been the standard for signal transmission and electronic control in control systems since the 1950's. In a current loop, the current signal is drawn from a dc power supply, flows through the transmitter, into the controller and then back to the power supply in a series circuit.
4-20mA Current loops are widely used to transmit process variable data such as temperature, pressure, flow rate, level, consistency, speed, etc between the process controllers and the field devices. Transmitters convert these process signals to 4-20mA DC for the purpose of transmitting the signal.
Basics of 4-20mA Current Loop. Figure 1 shows a schematic of the simplest 4-20 mA current loop. There are mainly four components: A DC power supply; A 2-wire transmitter; A receiver resistor that converts the current signal to a voltage; The wire that interconnects it.
The 4-20 mA current loop has become the standard for signal transmission and electronic control in most analog control systems. A 4-20mA current loop circuit is shown in Figure 1.