Geomagnetic Modules Technical Analysis | Core Sensors for Vehicle Detection at Industrial Gates
Suzhou Torchford Intelligent Equipment Technology Co. Focus on industrial door drive and security sensing field. Geomagnetic module (loop detector) as the core sensor for vehicle detection, how to achieve stable and accurate vehicle recognition is the key to the efficient operation of industrial doors and car park gates. This article will provide you with an in-depth analysis.
📌 Introduction to this article
- What is a geomagnetic module?
- Core Technology Principles
- Key Selection Parameters
- Common Troubleshooting
- Application Scenarios and Cases
1. What is a geomagnetic module?
The geomagnetic module is aIdentification of metal vehicles by detecting changes in inductance of induction loops mounted below ground levelThe sensor. When vehicles, forklift trucks, hydraulic trolleys and other metal objects enter the detection area, they will cause a magnetic field disturbance, and the geomagnetic sensor detects the change and outputs a switching signal, triggering the opening of the door or recording the status of the parking space.
Compared to radar, the geomagnetic module'sCore strengthsIs:
- Unaffected by rain, snow, dust, light and extremely stable
- Replacement for conventional ground sensing coils without cutting into the ground (pre-buried)
- Particularly suitable for forklift trucks, hydraulic trailers and other frequent access sites
Suzhou Torchford provides a full range of geomagnetic modules (ProLoop / ProLoop2) using Swiss technology, with IP65 protection, 9 levels of adjustable sensitivity, automatic sensitivity boost (ASB) and other features, widely used in industrial doors, car parks, car park management, parking space guidance systems and other scenarios.
2. Core technical principles
The geomagnetic module works by detecting the presence of a sub-surface mountedinduction loopof inductance changes to identify metal vehicles. The loop and the capacitor inside the detector formLC oscillator circuit, when a vehicle enters the magnetic field generated by the loop, it changes the loop inductance, resulting in an increase in the oscillation frequency. The detector detects that this frequency change exceeds the set sensitivity threshold and the output relay contacts switch.
Core parameter requirements：
- The optimum range of loop inductance values is 80-300μH
- Loop connectors need to be at least one per metreStranding 20 times
- The loop resistance should be less than 8 ohms(with connecting cable)
Multi-loop anti-crosstalk: When several geomagnetic modules are installed next to each other, mutual interference can be avoided by setting different oscillation frequencies (F1/F2/F3/F4) or using different numbers of coil turns.
3. Key selection parameters
| parameters | instructions | recommended value |
|---|---|---|
| Loop Inductors | Induction loop inductance | 80-300μH |
| operating voltage | Scope of supply | 24V DC / 230V AC |
| protection class | dustproof and waterproof | IP65 (detector) / IP67 (loop) |
| (level of) sensitivity | 9 adjustable levels | S1 lowest / S9 highest / S4 factory |
| frequency range | anti-crosstalk | F1/F2/F3/F4 four-speed selectable |
| operating temperature | - | -20°C to +60°C |
| output relay | Contact capacity | 240V AC / 2A max. |
Suggestions for selection：
- Standard industrial doors/gates: Select ProLoop Lite Series (Economy)
- Alarm output required: Option ProLoop2 A series (with alarm output)
4. Common Troubleshooting
❓ Trouble 1: No detection response when vehicle passes by
✅ Examine the steps:
① Check that the power supply voltage is within specifications (24V DC / 230V AC);
② Check that the loop inductance value is within the range of 80-300 μH (measured using a detector);
③ Check that the loop connection wire is twisted at least 20 times per metre;
④ Check that the loop resistance is less than 8 ohms;
⑤ Check if the sensitivity setting is too low and increase the sensitivity gear appropriately.
❓ Fault 2: False triggering when no vehicle is present (opens door by itself)
✅ Examine the steps:
① Check for crosstalk from neighbouring loops and set different frequencies;
② Check for moving metal objects (e.g., forklift, wheelbarrow) around the loop;
③ Check for loose probe rings or unstable ground;
④ Check the insulation resistance (need to be >10MΩ at test voltage 250V), if not up to standard need to be replaced.
❓ Trouble 3: Indicator light flashes abnormally
✅ Examine the steps:
① Check the loop insulation for damage and measure the insulation resistance;
② Check that the joints between the loop and the connecting wires are watertight and sealed;
③ Check that the sealant (asphalt or synthetic resin) is completely filled and free of cracks.
5. Application scenarios and cases
- Industrial doors open automatically by inductionForklift trucks and hydraulic trailers enter and exit frequently. The ground magnetic module is buried on the ground, and the door is automatically triggered to open when the vehicle passes by, without the need for the driver to get out of the car to operate.
- Car park entrance/exit gateAutomatic lifting of the pole when the vehicle arrives, automatic dropping of the pole after passing, together with the parking space counting system.
- Anti-smash protection: Linkage with the road gate system to ensure that vehicles are not hit when the road gate is dropped
- Car parking guidance system: Detect whether a parking space is occupied by a car and display the number of empty spaces in real time
- Forklift/trolley inspection: High sensitivity setting for detecting smaller metal objects
6. Summary and recommendations for selection
The geomagnetic module is a reliable choice for vehicle detection at industrial doors and car park gates, and is particularly suitable for scenarios with high stability requirements and harsh environments (rain, snow, dust).
For more product information or selection support, please contactSuzhou Jufu Intelligent Equipment Technology Co., Ltd.
