How a Loop Detector Works???
How a Loop Detector Works???
The loop is placed under the road surface, usually in a rectangular shape, at a depth of around 50mm. This keeps it out of view and reduces the likelihood of anything going wrong. It is then connected to a loop extension cable, often using an M12 connector, which joins up with the actual loop detector.
A magnetic field runs from the loop to the detector and if no traffic is present this remains at the same frequency. The detector monitors the frequency and if a vehicle passes over it will change the frequency. This causes the relay to close and triggers the reaction — for example, it opens a gate or changes the traffic lights. Once the vehicle has gone past, the relay will open again, closing the gate or changing the lights back again.
评论
发表评论