surge protective device?

As electronic equipment and precision instruments for the increasingly widespread, devastating lightning, lightning will directly or indirectly (through electromagnetic induction) invasion of the electrical channel and metal channels (such as power lines, signal lines and metal pipes, etc.). The resulting over-voltage and lightning surge voltage will have electrical equipment, communication and information system to produce great harm, ranging from damage to lines, heavy damage to electrical equipment, the system is paralyzed, resulting in incalculable loss. Over-voltage protection is an integral ring.