Lightning strikes, a natural phenomenon, are one of the key causes of EMI. Lightning surges are brief but powerful over-voltages and over-currents generally accompanied by EMI/RFI lasting up to a duration of a few hundred microseconds. But in that short duration they reach an excess of 100,000 volts.
Besides natural sources such as lightning, power system faults and utility grid switching to internal sources which are generated by load switching also generate such destructive surges.
A lightning surge has an enormous effect on electrical equipment, especially because we are not prepared for it or even aware of the damage. The strike may happen somewhere and the voltage surge may get transmitted through power cables which act like antenna, to equipment installed at a distance. With such repeated strikes, continuous deterioration and damage may occur.
IEC 62305 is the overall guideline for all applications when dealing with lightning and surge protection. This standard covers all the parameters: risk analysis, external and internal lightning protection.
Lightning rods are installed on building tops to mitigate this problem. They are directly grounded so that the lightning strike (which might be thousands of volts) bypasses the main building.
However, the after effects of the strike may lead to strong magnetic fields in the ground which create electrical interference and corrupt magnetic memory and other devices.
During the planning stage of building construction, earthing or equipotential bonding facility of sufficient size must be incorporated. All overhead and underground cables and power lines must be connected to it. During the electrical installation, care must be taken to ensure that electrical systems with dissimilar rated voltages are kept separate. Shielding of lines that can influence each other is a good way to achieve maximum electrical isolation.
Surge suppressors: Once voltage rises above expected level, the surge protector comes into play. It suppresses the excess voltage, diverts it safely to the ground and prevents it from causing any harm. When used together with air terminals, grounding rods, these surge arrestors form an industry's total lightning protection system. These arresters are best installed directly before the device to be protected. This can be in a socket or trailing socket (on extension lead) but also in the terminal or junction box of the device itself.
Filter circuits: To protect against permanent interference such as "ripples" or "noise" caused by other systems, additional filter circuits are used for the voltage supplies to devices.
Lightning guards: plug into a mains socket to moderate power from the grid, also into a telephone jack in order to monitor and control power into telecommunication lines and equipment.
EMIS has a strong presence in solutions for surge protection. Customer specific solutions are also delivered on request, apart from filters and shielding solutions from the product catalog. High reliability, MIL-grade solutions not only provide one of the smallest footprints available in the market, but also the added flexibility of widely ranging interconnect options for ease of integration into existing systems. Comprehensive Testing and consultancy services can also be availed to meet various industry and military standards.