LIGHTNING PROTECTION fOr
robot LAWN MOWERS
Lightning is an electrical discharge between clouds or between ground and a cloud. The lightning itself lasts only a fraction of a second and the voltage causing the lightning are many millions of volts. The current is often 100,000’s of amps. A lightning is a huge and often visible energy discharge.
If the lightning strikes between cloud and ground, it seeks the point on the ground where the conductivity is at its best, often a tall building, a tall tree or a damp area. The lightning branch out easily during a strike in the ground and it is often one of these branches that leads into the boundary wire of your lawnmower. What happens then is that the lightning finds its way to the circuit boards in the charging station and then aim for the point that is best grounded. This is usually the ground connection in the wall socket. If you pull out of the mains plug during thunderstorms, the lightning seeks the shortest route to something else that is grounded, which can be a damp underside of the charging station. The result in both these cases is that the electronics in the charging station are damaged.
Is it not safe to just unplug the mains?
Unfortunately, it is not at all certain that it will help to unplug the wall socket. In some cases, it can even make the damage worse. If the lightning strikes between the clouds but relatively close to the boundary wire, the boundary wire acts as a large antenna. A lightning that strikes between the clouds at a height of a few kilometers is more than enough to damage the electronics in a charging station. In this case it does not matter at all if you unplug the wall socket. The energy transferred from the lightning to the boundary wire is fed directly into the charging station. The longer boundary wire you have, the more energy the wire can absorb and it increases the risk of transient damages. The absolute safest way is to disconnect the boundary wire and any guide wires from the charging station in combination with disconnection from the mains. This protects the charging station and the lawn mower in a very safe way.
intonum's LIGHTNING PROTECTION
But you cannot disconnect the charging station if you are not at home when the weather is changing and when there is a risk for a thunderstorm.
An alternative is to protect the charging station and lawnmower with a lightning protection.