Two devices using 4…20 mA are not automatically compatible: it also matters which component powers the loop. A passive two-wire transmitter receives power and sends its measurement through the same conductors.
Energy and signal paths
PR 3186A2 is a two-channel galvanic isolator powered from the output loop. It uses energy from that loop to supply the passive transmitter at the input and reproduces the measured input current at the output with 1:1 transfer.
Galvanic isolation transfers the measurement information without a direct electrical connection between input and output circuits. Loop-powered operation does not remove the need for a source: the output loop still requires a power supply.
Checking the available voltage
The supply voltage must cover the transmitter requirement and the voltage drops across the isolator, cables and receiver input. Check this budget for the actual circuit before connecting it.
During commissioning, trace the energy path separately from the signal transfer. This helps distinguish an insufficient supply from a measurement scaling problem.
Source: ATSEN LinkedIn post, 07.10.2026.