RISK EVALUATION IN LIGHTNING AND OVERVOLTAGE PROTECTION

Abstract

With the development of electronics several tendencies whose joint emergence redoubles the significance of damages to electronic parts is visible simultaneously today. The complexity of systems of electronic devices is increasing continuously, and there are large arborescent networks that allow various electromagnetic effects threatening to harm the equipment to spread easily, while society is more and more dependent on the operation of complicated systems. The present paper summarises and classifies the electromagnetic phenomena representing actual danger to electronic equipment. By extending the idea of `strokeless period´, which is widely used in lightning protection, a general mathematical method is introduced for defining the probability of damage. This method will then serve as a basis for a concept for overvoltage protection and it will allow to make decisions on the necessity and economic efficiency of protection. It presents a detailed calculation for the probability of the occurrence of overvoltage waves entering buildings through electric conduction as a result of a stroke of lightning, which is one of the most uncomfortable effects coming from our environment.