What Is a Loop Detector?
A loop detector is a sensor designed to detect metallic or conductive objects. It operates by monitoring changes in electrical current within a loop when such objects pass through or near it.
The principle of operation depends on the loop’s current variations. In constant current mode, a steady current flow through the loop. The presence of a metallic or conductive object is identified by a noticeable decrease in this current. Conversely, in pulse current mode, the loop is energized with pulsed currents. Here, the detector identifies changes in the peak values of these currents, indicative of an object’s presence.
Commonly used in security, surveillance, and traffic management systems, loop detectors are crucial for identifying the presence of metallic objects. A typical loop detector system comprises three main components: a metal wire loop that creates the detection field, the detector unit that monitors current changes, and the output circuit that communicates the detection event.