21/10/2026
How to connect Loop Powered Sensors. In our electrical education days when we learned basic electrical theory in conjunction with Ohm’s Law, we learned that DC current is equal and constant in a simple series circuit represented by a closed loop. Voltage was a different situation. Depending on resistances in that simple series circuit, the voltage would vary at different points. Herein lies the main reason that DC current has become the most common industrial signal used to connect measurement sensors back to indicating control systems. A current signal will remain constant regardless of the resistances of the circuit. The signal can travel very long distances. A voltage signal will change along the circuit due to the vary resistances of wires and connection points limiting usefulness to very short distances. The objective is to transmit the value from the sensor to the control system input without being affected by the wires on which the signal travels. https://www.pyrosales.com.au/blog/thermometer-and-infrared/how-to-connect-loop-powered-sensors/
