Severe Environment

Installation in a severe environment usually has following characteristics.

The device is installed in an open field without any shelters.
The device is installed on a high position with no higher objects nearby, for example, at the top of a building, pole, or mountain.
The cables are routed over a long distance.

In severe environments, the device has a higher risk to be damaged by lightning strikes. Different types of lightning hazards and solutions are as follows.

Table 1. Lightning Hazards and Solutions in Severe Environments
Type	Description	Solution
Direct Strike	The device is not sheltered and at the risk of being struck directly by lightning.	Install lightning protection system and keep the device within its protective radius.
Ground Potential Rise	When a nearby object is hit directly by lightning and the resistance on its releasing path is too high, if the device and the object have the common ground, the transient current and high voltage will go into the device through the ground wire and cause damage.	Ground the device separately. Avoid common ground with the lightning protection system.
Lightning Electromagnetic Pulse	In an open field, the electromagnetic pulse caused by electric discharge from cloud to cloud or from cloud to ground couples into the wires of the device through space and causes damage.	It is usually required to enclose device cables with shielded metal pipes and ground the metal pipes. Long-distance cables are required to be buried underground. Overhead wiring is not allowed. Every line into the device should be installed with SPD.
Surge Energy	When the cable runs over a long distance, the surge energy from the far end also poses high risk.

Figure 1. Lightning Protection Measures in Severe Environments