Power Problems: Transient Suppression in the Power Chain

Causes of Transients

The impact of a lightning stroke on any conductor like electrical or telecommunication cables produces transient overvoltages which are characterized by a short duration, rapid amplitude growth and high peak values (up to 200 kV - i.e 200,000 Volts).

The discharge of a lightning flash is propagated within a radius of several kilometers. Inside this area the strike raises the potential causing transients in cables located in the ground and in earth terminations.

Lightning is not the only reason for surge voltages. They are also caused by:

In an installation all the conductors which enter from outside are potentially a path for surge voltages, which can lead to damage and downtime in the power supply of the connected systems.


The surge voltages generated by a lightning strike produce very high currents in the electrical conductors (tens of kA) with a very short duration (some Ás). The conductors present a very high impedance against surge voltages due to the inductance of the cables at high frequency. With normal working frequency of 50Hz the impedance is negligible.

The single most important part of transient suppression therefore becomes the correct device and installation for your likely exposure

Fault Modes

Clearly it is just as important to protect against trasnients in both modes. For ease of Installation Advance has both modular systems with individual devices for each mode of protection and combined devices protecting against all modes.