The substantial cost of industrial network downtime due to malfunctions caused through electrical over-stress makes it necessary to protect network nodes, in particular against electrical transients caused by electrostatic discharge, inductive switching and lightning strikes.

The International Electrotechnical Commission (IEC) has, therefore, defined three transient immunity test standards to assure proper circuit operation during and after testing.

This article briefly describes these tests and suggests using an industrial RS-485 cable in combination with low-capacitance transient voltage suppressors as the most efficient way to protect your network.