Surge protection devices

Surge protection devices are devices whose essential components are voltage-dependent resistors (varistors, suppressor diodes) and / or spark paths (discharge pathways).

Surge protection equipment is intended to protect other appliances, equipment and electrical installations against excessively high surges and / or to establish potential compensation.



Surge protection devices can be classified as follows:

a) According to their application they are divided into:

• Surge protection devices for equipment and installations in the power grid (Red / Line product family) in the voltage range of up to 1000 V nominal voltage

- according to EN 61643-11: 2012 SPD Type 1/2/3

- according to IEC 61643-11: 2011 SPD Class I / II / III

• Surge protection devices for installations and equipment to be installed in data transmission networks (Yellow / Line product family) for protection in data transmission and signal treatment networks with nominal voltages up to 1000 V AC ( effective value) and 1500 V DC, against the direct and indirect effects of lightning discharges and transient surges

- according to IEC 61643-21: 2009, EN 61643-21: 2010 and DIN VDE 0845 part 3-1.

• Separation spark paths for grounding installations or for potential compensation (product family (Produktfamilie Red / Line)

• Surge protection devices for the protection of photovoltaic equipment and installations (Red / Line product family) in the voltage range of up to 1500 V nominal voltage

- according to EN 50539-11: SPD Type 1/2.


b) According to the capacity of the shock current derivation, they are divided into:

• Lightning current arresters / Coordinated lightning current arresters, for alterations due to direct or close lightning discharges. (Mounting at intersection points between lightning protection zones 0A and 1).

• Surge arresters, for protection against distant lightning discharges and surges caused by switching processes, as well as electrostatic discharge. (Mounting at the intersection points of the lightning protection zones that follow the 0B lightning protection zone).

• Combined arrester, for protection against lightning currents and surges (to be installed at the intersection points of protection zones 0A - 1 and 0A - 2).


Characteristics of the shock current: 

The characteristic parameters of the flowing shock current (peak value, wavefront, load and specific energy) are described with the shape of the 10/350 μs shock current wave and are set in international, European and national regulations. as a test current for components and protective devices in the event of direct lightning strikes. In addition to the voltage drop in the shock earth resistance, overvoltages occur in the electrical installation of buildings and in the systems and devices connected to it due to the induction effect of the lightning electromagnetic field. The energy of these induced surges and the resulting impulse currents of them are much lower than the lightning shock current in the case of direct discharge, and this energy is therefore described with the 8/20 μs shock current wave . Equipment and components that do not have to withstand currents caused by direct lightning strikes are verified and tested with 8/20 µs shock currents.

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