Surge protection for explosion hazard areas: Principles for ex-proof device

All electrical equipment needs special characteristics to installation in explosion hazard areas. These requirements are necessary to avoid an explosion caused by electrical current. Surge Protection Devices (SPD) are designed to conduct surge currents created by lightning discharges and switching operations. When the SPD are installed in explosion hazard areas, they need to fulfill two different requirements. Conduct the surge currents, avoiding the ignition in the explosive atmosphere.