Modern electronic equipment is particularly vulnerable to transient voltages due to microcontrollers and other internal components containing millions of active circuits in a package with increasingly smaller dimensions. Basic electrical theory means that the smaller the spaces between conductors the lower the transient voltage required to cause a flashover. Consequently, the voltage element of a transient will stress these components, and repeated exposure to such spikes will result in an otherwise healthy silicone device failing. Based on the utilisation of electronic components in all aspects of the modern facility this could result in process automation disruption, including variable speed drive (VSD) failure, computer, network, or general IT crashes, loss of data, or the need for premature equipment replacement. Electrical spikes may also cause nuisance tripping of RCDs
Methods for protecting against transients largely depend on what the voltage, duration and power levels of the transients are, and the nature of the equipment connected to the installation. Power equipment, such as rotating machines, should be specified with an adequate level of insulation according to the point on the supply to which they are connected.
In the world of test equipment, we have to develop products such that they are able to withstand specific transient voltages depending on the point on an electrical installation to which they will be connected and used according to BSEN61010-1 (see table). This basically recognises that externally generated transients of a certain magnitude will appear at an installation, with that transient slowly reducing in voltage as it moves through the installation wiring due to the effects of that wiring and the installation equipment. In other words, products connected at the point of the supply need to be able to withstand transient voltages higher than products designed to be connected to the fixed wiring within the supply, which in turn experience higher voltage transients than items plugged into a wall socket, and so on.