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This paper provides practical guidelines on when and how to introduce signal isolation into 4-20mA loops without affecting loop integrity. What is the problem? A ubiquitous problem with plant is the interface of every industrial plant measurement signals to the monitoring and control systems.
16 wrz 2022 · I have a PLC that is powered with 3.3 V and a sensor powered with 12 V that outputs a 4-20 mA signal. In order to allow the signal to be readable by my PLC while isolating the current in the 12 V loop from the 3.3 V loop I need to use an opto-isolator which I have never used before.
23 paź 2024 · The 4-20mA current loop has been the standard for analog signal transmission in the industrial environment for more than 70 years and, judging by number of transducers that support it today, will be around for a bit longer yet!
2 gru 2020 · 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.
Adding isolation to the 4-20mA current loop protects system electronics from electrical noise and tran-sients. It also allows transducers to be electrically separated by hundreds of volts. Burr-Brown now offers all of the integrated circuit building blocks needed to assemble com-plete isolated 4-20mA current-loop systems.
This application note introduces three designs regarding to isolated power supply for two-wire loop-powered 4 to 20mA field transmitter system. Design 1 runs at a fixed switching frequency of 50kHz offers the highest efficiency at 5V input voltage, reaching 86%, and maintains a higher efficiency at lower input voltages.
The passive isolator ACT20M-CI-CO-OLP-S isolates standard analogue current signals. An analogue input current signal is linearly converted into an analogue output current signal and is galvanically isolated. Power is supplied through the output measuring circuit (output loop-powered).
