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New guide sees a surge in understanding

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REO UK has produced an impartial and practical guide to the EMC standard, EN 61000-4-5, which deals with surge testing. Typical urban buildings suffer from surges of about 6kV about three times a year. These can be caused by slow mutual inductances or common-impedances. However, they are often caused by normal, unavoidable thunderstorm activity in the local area. The REO guide explains the EMC rules on surge testing and how to avoid resulting problems.

Unlike many EMC tests, ‘do-it-yourself’ surge testing is easy and low cost because it uses low frequencies and does not need a special test environment. Although the EMC directive does not require that all surge tests listed under EN 61000-4-5 be carried out, it can make good financial sense to go beyond simple compliance. Full testing can make a company’s products more reliable, reduce its warranty costs and its exposure to product liability claims, and improve its customer satisfaction. Surge testing can avoid electrical, thermal and energy overstress, and even damage to electronic devices.

Surges can be created by switching events and insulation faults in AC power distribution networks, by the switching of reactive loads such as electric motors or power factor capacitor banks. These surges are essentially caused by the sudden release of the energy stored in the system. Surges can also be created by lightning and superconducting magnets, such as those used in MRI scanners, which release a great deal of energy when their field collapses owing to a loss of superconductivity.

The REO guide offers advice on full compliance testing as well as low cost testing

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