Surge Protection Devices

Concept of Surge Voltage

Every electrical device has a specific dielectric strength against surge voltages.

If the level of a surge voltage exceeds this strength, malfunctions or damage can occur.

Surge voltages with very high amplitudes in the kilovolt range are generally transient

Overvoltage’s, which means they have a comparatively short duration, ranging from a few

Microseconds to several hundred microseconds. The high amplitude and short duration, in turn,

Mean very abrupt voltage increases and high voltage differences, the effects of which can be

Protected against only with surge protection

Types of Surge

Mep-SPS-Surge Concept

  1. Lightning Surge: (10/350 microsec waveform)

Sources:  Strike on Power Supply, Telephone Lines, Internet Lines or sudden lightning


  1. Internal Surges: (8/20 microsec waveform)

Sources:  Internal switching of Resistive and Inductive Loads

Surge Protection Devices (SPD) : Dehn Make

  • Surge Arrester (Type-I SPD)