Parking lot buried coil considerations

First, the coil material

Under ideal conditions (without considering the influence of all environmental factors), the placement of the geomagnetic coils only considers the size (or perimeter) and the number of turns of the area, regardless of the material of the wire. However, in practical engineering, the mechanical strength of the wire and the anti-aging problem at high and low temperatures must be considered. In some harsh environments, the problem of acid and alkali resistance must also be considered.

The detector will not work as soon as the wire is aged or the tensile strength is not enough to cause the wire to break. In practical projects, it is recommended to use high-temperature multi-stranded flexible conductors of 1.0mm or more Teflon.

Second, the coil shape

1, rectangular installation

Usually the search coil should be rectangular. The two long sides are perpendicular to the direction of movement of the metal objects. The distance between them is recommended to be 1 meter. The length of the long side is determined by the width of the road, which is usually 0.3 meters to 1 meter narrower than the distance between the roads.

2, tilt 45 ° installation

In some cases when it is necessary to detect a bicycle or a motorcycle, consider installing the coil at an angle of 45° to the direction of travel.

3, "8" shaped installation

In some cases, when the road surface is wide (more than six meters) and the chassis of the vehicle is too high, this type of installation can be used to disperse the detection points and increase the sensitivity.

This type of mounting can also be used for sliding door detection, but the coil must be close to the sliding door.

Third, the number of turns of the coil

In order to operate the detector under optimum conditions, the inductance of the coil should be maintained between 100uH-300uH. With the coil inductance constant, the number of turns of the coil has an important relationship with the perimeter. The smaller the perimeter, the more loops there are. Generally refer to the following table:

3 meters or less, according to the actual situation, to ensure that the inductance value is

Between 100uH-200uH can be 3-6 meters 5-6 inches

6-10 meters 4-5 inches

10--25 meters 3 inches

25 meters above 2 feet

Since there may be buried under the road with various metal materials such as cable lines, steel bars, and sewer covers, these will have a great influence on the actual inductance of the coil, so the data in the above table is for reference only. In actual construction, the user should use the inductance tester to actually measure the inductance of the ground inductance coil to determine the actual number of turns of the construction, as long as the final inductance of the coil is within a reasonable working range (eg, between 100uH and 300uH).

Fourth, the output lead

When winding the coil, leave a sufficient length of wire to connect to the loop inductor and ensure there is no connector in the middle. After winding the coil cable, the outgoing cable must be made in a tightly twisted form, requiring at least 1 m twisting 20 times. Otherwise, untwisted output leads will pull in, making the coil inductance unstable. The output lead length should generally not exceed 5 meters. Since the sensitivity of the detection coil decreases as the length of the lead increases, the length of the lead cable must be as short as possible.

Fifth, laying method

The coil is first embedded in a slot cutter on the road. Perform 45-degree chamfering on the four corners to prevent sharp corners from damaging the coil cable. Groove width is generally 4 to 8 mm and depth 30 to 50 mm. At the same time, a slit for the coil lead to the curb must also be cut. However, it should be noted that the grooves must be clean and free of water or other liquids. The coil must be straightened when it is wound, but do not stretch too tightly and close to the bottom of the groove. After winding the coil, the twisted output lead is led out through the lead slot.

In the winding process of the coil, the inductance value of the inductance coil should be measured by an inductance tester, and the inductance of the coil should be between 100uH and 300uH. Otherwise, adjust the number of turns of the coil.

After the coil is buried, a nylon rope may be wound around the coil for protection. Finally cut the groove with asphalt or soft resin.