(The isolator itself does not need power supply) is to use the signal current in the input loop to power the instrument (refers to taking part of the energy of the input signal inside the signal isolator to drive the isolator to work), without any external power supply. Signal isolator wiring diagram.

Passive signal isolator wiring diagram:

Active signal isolator (isolator itself needs power supply, conventional power supply is DC24V), the use of active signal isolator in the control system, the need to install the signal isolator and support the signal isolator work in the control cabinet of the control system. If the passive isolator is used, it both plays the role of signal isolation and does not need to use the power supply that supports the work of the isolator, which can save one-third of the wiring workload, the cost of the power cable and the power supply itself. Signal isolator wiring diagram

Active signal isolator wiring diagram: