Two Case Studies on Energy and Protection Level Coordination of an SPD System

There are various factors that may be responsible for allowing lightning related equipment damage. If lightning protection measures have not previously been implemented, it is possible to lessen the damage by installing Surge Protective Devices (SPD's). However, it is a problem when lightning damage has occurred in spite of the fact that lightning protection measures have been taken. In such cases, the damage may have happened because (1) the energy handling capabilities of the SPD's were not coordinated properly, (2) the SPD was not selected on the basis of its effectiveness for the particular equipment to be protected, and/or (3) the grounding conductor connected to the SPD was too long. It has been confirmed that lightning related damage to equipment can be caused by the lack of sufficient current withstand capability of the SPD or by insufficient protection coordination between SPD's and the equipment to be protected. We introduce actual cases of lightning protection measures.