Installation Considerations:
When installing overseas, the grounding resistance should also meet the relevant requirements of the country or operator.
Part 1: Lightning Protection in Harsh Environments
Harsh environments generally have the following characteristics:
- open areas with no other obstructions;
- the installation location of the equipment is particularly high, typically higher than surrounding objects;
- The equipment is usually installed on buildings, poles, or mountain tops;
- Additionally, the cables for the equipment are generally long.
In these environments, the risk of lightning strikes to the camera is high, typically with the following four risk categories:
Risk 1 – Direct Lightning Strike: The equipment is completely exposed to lightning, making it susceptible to being struck directly.
Risk 2 – Ground Potential Rise: When surrounding objects are hit by lightning, the object’s discharge path has high impedance, and if the equipment shares the same grounding, transient currents and high voltage may flow back through the grounding wire, damaging the equipment.
Risk 3 – Lightning Electromagnetic Pulse (EMP): In open areas, when cloud-to-cloud or cloud-to-ground discharges occur, electromagnetic pulses can be induced by spatial coupling and affect the equipment’s cable lines, potentially damaging the equipment.
Risk 4 – Surge Energy from Long-distance Cable Transmission: Surge energy transmitted through long cables can be a significant risk.
Measures:
For Risk 1, install a lightning rod to keep the equipment within its protection range, thereby avoiding the risk of direct lightning strikes.
For Risk 2, the equipment must be grounded separately and not share the same ground with the lightning rod.
For Risks 3 and 4, it is typically required to shield the incoming cables with metal conduits that are grounded. For long-distance cables, they should be buried underground, and overhead installations should be avoided. Additionally, surge protectors should be installed on each line entering the equipment.
Part 2: Lightning Protection in Outdoor Environments
Outdoor environments usually have the following characteristics:
- installations outdoors, often near lightning rods or higher buildings.
- The equipment cables are generally long.
In these environments, the risk of direct lightning strikes is smaller due to the presence of lightning rods or taller structures, but the risk of indirect lightning is still significant. The common scenarios include:
- Lightning EMP: In open areas, electromagnetic pulses induced by lightning discharges can travel through space and couple into the cables, damaging the equipment.
- Ground Potential Rise: Similar to the previous part, transient currents and high voltage from a lightning strike on a nearby object can travel through the grounding system, damaging the equipment.
- Surge Energy from Long-distance Cable Transmission: This is also a significant risk when transmitting surge energy over long distances.
Part 3: Lightning Protection in Indoor Environments
Indoor environments typically do not face direct lightning strikes, but the risks associated with lightning EMP and ground potential rise should still be considered.
Protecting against lightning EMP can be costly, and since the occurrence probability is low, it is generally not specifically addressed, relying on the building’s lightning protection instead. To prevent ground potential rise, the use of building lightning protection systems such as lightning rods for grounding should be avoided.
