Loop detector should be used to detect metal objects such as vehicles, bicycles, etc. It is suitable for parking lots, road vehicle toll stations and signal light control systems. Loop detector adopts the most advanced microprocessor technology, which can meet the application in various usage environments. When a metal object passes through a coil buried under the road, because the metal conductor will change the inductance of the coil, the loop detector detects the metal object by detecting the change in the inductance of the coil.

Working principle of loop detector: The loop detector detects the metal object by detecting the change of the inductance of the metal object on the induction coil. The coil is wound by multiple turns of wire, buried under the road, and filled with cement. The coil lead is connected to the loop detector. When a metal object passes through the induction coil, the inductance of the conductive coil changes somewhat. This change is detected by the loop detector, and it is judged that there is a metal object through the calculation of the internal intelligent controller, and the signal is output through the output relay. Due to the intelligent control function of the microprocessor, the sensitivity of the loop detector can be adapted to various requirements, and it can also be well matched to different sizes of induction coils and leads. Coil tuning: The tuning process of the loop detector is completely automatic. When the loop detector is powered on or reset, it will automatically tune to the coil it is connected to, and the tuning range is 50 to 1000 μH. Such a wide tuning range ensures low requirements for coils and leads. Once tuned, any environment will feed back the compensation circuit inside the detector to slow changes in inductance to ensure normal operation. Sensitivity: The sensitivity of the loop detector depends on such factors as the size of the coil, the number of turns of the coil, the length of the lead wire, and whether there is metal under the circle. The sensitivity of the loop detector should be determined according to the specific application. The sensitivity of loop detector is specially optimized for parking lot management system. When selecting a lower sensitivity, smaller objects like bicycles, trolleys, etc. will not cause the detector to move, and it can be well adapted to vehicles with higher chassis and vehicles with trailers. Reaction time: The reaction time of the loop detector is defined as the time interval from when a metal object enters the induction coil to when the loop detector gives an indication signal. The reaction time of loop detector is specially optimized for parking management system, generally 100 milliseconds. Too short reaction time is likely to cause malfunction in an environment with electromagnetic interference, and too long reaction time will also cause inconvenience in use.