Vehicle Detector Using Loop Coil: Installation and Specifications Guide

Vehicle Detector Using Loop Coil: Installation and Specifications Guide

Introduction 

Vehicle detectors based on inductive loop coil technology are widely used in parking system. These detectors reliably sense the presence of vehicles by detecting changes in the inductance of a wire loop embedded in the ground. This article provides a detailed overview of how loop coil vehicle detectors work, the installation process, and the technical specifications that ensure proper operation and integration. 

 

Process 

1. Loop coil detectors consist of two primary components: 
      - Inductive Loop: A coil of wire installed in or under the pavement. 
      - Detector Unit: An electronic module that detects changes in inductance when a vehicle passes over or stops above the loop. 

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2. Installation Process - Planning and Layout
      - Identify the ideal location for vehicle detection: typically just under a barrier arm. 
      - Choose the correct loop shape and size (commonly square or rectangular). 
       -Typical loop dimensions: 0.6 m × 1.5 m depending on the lane width. 

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3. Cutting the Loop Slot 
      - Use a concrete saw to cut grooves in the road surface to form a loop pattern. 
      - Groove depth: 30 mm to 50 mm 
      - Groove width: 5 mm to 8 mm
      - Create a diagonal or perpendicular slot for the lead-out cable to the roadside. 
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4. Installing the Loop Wire 
      - Use multi-strand insulated wire (commonly 1.5 mm² or 16 AWG). 
      - Wrap the wire 3 to 5 turns inside the slot, depending on sensitivity requirements. 
      - Avoid sharp bends and ensure the wire lies flat in the groove. 
      - Bring the twisted pair lead-out cable to the controller or detector unit. 


5. Sealing the Slot 
      - After wire installation, seal the groove using hot bitumen or epoxy sealant. 
      - Ensure the surface is flush and free of bumps to avoid damage by passing vehicles. 


6. Connecting to the Detector Unit 
      - Connect the twisted loop lead-out wire to the vehicle detector module. 
      - Configure the detector using DIP switches or software settings for: 
            a. Sensitivity level 
            b. Presence vs pulse output 
            c. Frequency settings (to prevent crosstalk between nearby loops) 


  • Technical Specifications (Typical) for Detector Unit 

Parameter 

Specification 

Operating Voltage 

12V–24V AC/DC 

Power Consumption 

< 2W 

Loop Inductance 

50 μH – 500 μH 

Frequency Range 

20 kHz – 130 kHz 

Response Time 

< 100 ms 

Sensitivity 

Adjustable (typically 8–10 levels) 

Relay Output 

NO/NC dry contact or solid-state output 

Loop Wire 

PVC-insulated, 1.5 mm², multi-strand copper wire 

Operating Temperature 

-20°C to +70°C 

Housing Protection 

IP40 to IP65 (depending on model) 




7. Notes:  
      - Avoid installing loops over steel-reinforced sections of concrete. 
      - Maintain a minimum of 2 meters between adjacent loops to avoid interference. 
      - Use proper grounding to prevent false triggers due to electromagnetic noise. 
      - Label and document loop layout during installation for future maintenance.