The HAW569 surge arrester is used to protect electronic components in field devices from being destroyed. It ensures that overvoltage surges which occur in signal cables (e.g. 4 to 20 mA), in communication lines of Field buses (HART, PA, FF) and in power lines are safely passed into the ground. The functionality of the electronic component to be protected is not affected as, using the impedance-free connection of the protection unit, interference voltage drops cannot be introduced.