Mains protections are designed for protecting against overvoltage of atmospheric origin (lightning and electrostatic) the equipments supplied in single and three phases 230/400 V ~ (ou 120/208 V~) as well on isolated sites as internal electrical installations.
Natural or provoked discharges can create very strong electromagnetic radiation over large distances. Networks then can meet overvoltage which can destroy all equipment connected to any nearby power lines.
(Highly energetic discharges with long duration times, overvoltage larger than the component’s damage threshold voltage of electronic equipment, inductive effects due to overvoltage with steep slopes).
These surge protective devices are designed for flowing to the earth the induced currents before they can reach the equipment connected to the downstream power network while the overvoltage are kept to a harmless level and the equipment running in total transparency for the user.
These devices are recommended for protecting any equipment connected to main power supplies in the case of domestic and industrial installations. The selection of the product’s type is done taking into account the exposition degree to lightning of the area (UTE-C 17108 or NF EN 62305-2 : installation in isolated or metropolitan area, cost and sensitive level of the equipment to protect, the neutral earthing system, the installation mode.
These products offer a large panel of performances with discharge current ranging from (5 kA to 160 kA in wave 8/20 μs and 10 kA to 100 kA in wave 10/350 μs), protection levels of 600 V (diode arrays or products based on the association of varistors and surge arrestors) to 4000 V (encapsulated spark gaps only), short response time, redundancy of the protection for applications in isolated areas, products for external applications…
They are installed in parallel with the mains in association to a circuit breaker against short circuits (mandatory only if not already provided by mains or when the upstream circuit breaker is not adapted, NFC 15-100, IEC 61643-1 and NF EN 61643-11).
Earthing is mandatory and it is done according to the rule of the shortest possible path (all earth conductors must be interconnected). Installation of a remote control system coupled to the circuit breaker or to the overvoltage protection with an overvoltage controller is recommended to secure the overall installation.