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Surge Protection

 

Our dependency on electrical and electronic equipment continues to increase, in both our professional or private lives. Data networks in companies or emergency facilities are lifelines for an essential real time information exchange.

It is not only lightning strikes that pose a latent threat to these systems. More and more frequently, today’s electronic aids are damaged by surge voltages caused by remote lightning discharges or switching operations in large electrical systems.


Direct Strike


The largest voltage peaks in the low voltage consumer network are caused by lightning discharges. The high energy content of lightning surges when a direct strike hits the external protection system or a low-voltage open line usually cause total outage of the connected consumers and damage to the insulation.



Induced Voltage peaks and switching surge voltages


The induced voltage peaks in building installations and energy or data line supply cables can also reach many times the nominal operating voltage. Switching surges too, which in fact do not cause such high voltage peaks as lightning discharges but occur much more frequently,can result in immediate system failure.


Lightning Protection zone concept


The lightning protection zone concept described in international standard IEC 62305-4 (DIN VDE 0185 Part 4) has proved to be practical and efficient. This concept is based on the principle o gradually reducing surges to a safe level before they reach the terminal device and cause damage. In order to achieve this situation, a building’s entire energy network is split into lightning protection zones (LPZ). Installed at each transition from one zone to another is a surge arrestor for equipotential bonding.



Benefits of the lightning protection zone concept


          Minimisation of the couplings into other cable systems through arresting the energy-rich,dangerous lightning currents directly at the point the cables enters the building.

·           Malfunction prevention with magnetic fields.

·          Economic,well planned individual protection concept for new and old buildings and reconstructions.


Type classes of the surge protection devices


Surge protection devices are classified in accordance with IEC 61643-11 into three type classes – type 1,type 2 and type 3. These standards contain building regulations, requirements and tests for surge arrestors used in AC networks with nominal voltages of up to 1,000 V and nominal frequencies of between 50 and 60 Hz. This classification enables arrestors to be matched to different requirements with regard to location, protection level and current carrying capacity.