1 Environmental characteristics:

1.1 Geographic location: usually located in the open area near the highway or the entrance and exit of enterprises and institutions; 1.2 Implementation conditions: the weighbridge station is generally composed of a single-storey management room and a weighbridge bearing platform, with a small building area, and often does not have the required lightning protection devices (including grounding grid, external lightning protection and internal lightning protection); 1.3 Power supply system: 220V AC power supply lines are generally overhead open lines entering the station room, without underground measures, so it is very easy to induce lightning electromagnetic pulse; 1.4 Sensing signal system: the sensor with DC working voltage of 12V is installed under the steel plate of the load-bearing platform and connected to the computer system through a 9-core cable. Generally, the steel plate is not grounded, and the cable is not shielded through the tube;

2 Confirmation of lightning protection category

In accordance with the requirements of Article 6.1.2 of GB 50057-94 Code for Design of Lightning Protection of Buildings, the weighbridge station shall be a Class III lightning protection building, with lightning protection belt and other lightning protection measures, and the electronic weighbridge system shall be provided with lightning protection electromagnetic pulse measures.

3 Design of grounding network

The grounding of the weighbridge station shall adopt the common grounding form, that is, the direct lightning protection grounding, the AC working grounding, the signal line DC working grounding, etc. share a grounding grid, and the grounding resistance of the grounding grid shall be ≤ 4 Ω. The electric cable sheath or steel pipe, the two ends of the metal sleeve of the sensor signal transmission line, the two ends of the steel plate of the weighbridge bearing platform, and the metal water pipe entering the management room shall be equipotentially connected with the grounding device nearby. The signal line shall avoid the lightning protection downlead as far as possible, and the distance is generally more than 1 meter. The grounding device of the weighbridge station surrounds the management room and the weighbridge bearing platform IV

The circular grounding body shall be laid at the place more than 1m away from the apron slope, and the horizontal grounding body shall be 40 × 4mm galvanized flat steel, buried depth 1m, vertical grounding body L50 × five × Galvanized angle steel of 5mm and 2500mm long shall be driven every 5m. When the grounding resistance cannot meet the design requirements, the tree-fork type external grounding device can be used according to the terrain, and the external grounding length should not be greater than the effective length.

4 Design of direct lightning protection

The floor of the house managed by the weighbridge station shall be equipped with lightning protection strip around, and a 50cm high lightning rod shall be set at the four corners, and four down conductors shall be set at the four corners to connect with the grounding grid. All metal components such as the roof metal pipes, billboards, etc. shall be well equipotential connected with the lightning protection strip, and anti-corrosion treatment shall be done.