INTRODUCTION

The increasing usage of computers achieves an improvement in the industrial process and quality control. It has now become a necessity for many application to work in a local area network in order to exchange information within the project group or department.

Statistics indicate that the problems caused by surge voltages in date lines have increased over the last years, along with a high volume of economic losses. This is due to the high number of computer systems used and their high inherent sensitivity to surge voltages.