PROTECTION OF ELECTRONIC EQUIPMENT AGAINST HIGH-VOLTAGE SHORT-DURATION SURGES IN THE MAINS POWER SUPPLY

Abstract

The problem of electrical and electronic equipment immunity to high- voltage short- duration power supply surges, specifically high- energy microsecond surge disturbances, is considered. The causes of microsecond surge occurrence, with amplitudes reaching 2 kV and higher, are shown. A review of various methods and means of equipment surge protection has been conducted, demonstrating that the most effective approach is the use of two- terminal devices with highly non- linear current-voltage characteristics: varistors, suppressors, and gas discharge tubes. The operating principles of these two- terminal devices were analyzed, showing that standard direct connection at the equipment power input is insufficiently effective when the power network impedance is low at frequencies corresponding to the surge duration. An L -shaped connection scheme incorporating an LR -circuit alongside a two - terminal non-linear device is proposed. The obtained results indicate that this topology reduces the surge amplitude at the power input by 1.5 times more than a standalone non-linear device, even under low power grid impedance at high frequencies. The addition of a multi-stage π-type low-pass filter allows for reducing the surge amplitude by 20 times or more compared to conventional varistor or suppressor arrangements.