DEHN arc fault protection FAQ
FAQ - Smart Energy

FAQ – Lightning and surge protection for smart energy

Answers to the most frequently asked questions about smart energy


Q: What exactly does DEHN understand by smart energy?
A: In the future, the structures for power generation, transmission, distribution and consumption in all voltage ranges (high, medium and low voltage) will be more complex and flexible than they are today. New topics such as smart grid, smart metering and smart home require innovative solutions. But also the rapid rise of distributed, renewable energy sources, in combination with centralised power stations, energy storage systems and intelligent technologies, need a reliable and coordinated overall system. Such a crosslinked energy market is also referred to as smart energy.


Q: Is smart energy the same as smart metering?
A: No, the future power grid is far more than just smart metering! Smart energy includes comprehensive solutions and topics such as intelligent transformer substations, monitoring and telecontrol systems, regulated distribution transformers, longitudinal voltage controllers, energy storage systems, energy efficiency, data concentrators, etc.


Q: Which standards are relevant for protecting transformer substations from lightning strikes and surges?
A: The following standards of the IEC 62305 series can be taken as a basis for the protection concept:

  • IEC 62305-2
  • IEC 62305-3
  • IEC 62305-4

In addition, IEC 60364-1:2005 and particularly IEC 60364-4-44:2001 describe how to protect electrical installations in case of atmospheric surges which are transferred via the power supply system and surges caused by switching operations.


Q: How high is the risk that lightning strikes a transformer substation?
A: Due to the small design of a typical transformer substation, the risk of a direct lightning strike is low particularly in case of attached building development. Thus, nearby and remote lightning strikes are statistically most likely to occur and they are therefore the most frequent types of lightning strike. In case of large or isolated substations in exposed locations, a case-by-case evaluation is required.


Q: Which areas of a transformer substation are to be protected?
A: The areas of power supply and information technology systems requiring protection are, for example: The transformer/regulated distribution transformer, main low-voltage distribution board, monitoring and telecontrol systems, other intelligent equipment, etc.


Q: How are interference impulses injected into a transformer station?
A: To protect the substation, secondary and telecontrol technology, the supply voltage always has to be protected and in case of cabled transmission of light-current signals, also the communication interface has to be protected. The same applies to the transmission technology with external antennas where surges are only to be expected due to the field of the lightning channel. Conducted interference impulses can enter the substation via the high-voltage and low-voltage side or via two-wired communication interfaces. In the latter case, a direct or a nearby lightning strike close to the relevant conductor system can occur.


Q: Which DEHN products can be used for the market segment smart energy?
A: Red/Line products ensure lightning and surge protection for power supply systems and Yellow/Line products for information technology systems. Moreover, external lightning protection products, safety equipment and a variety of services are available - Everything from one source!


Q: Does an arrester have to be replaced after each discharge process?
A: No, DEHN surge arresters can repeatedly discharge lightning currents. This was also proven in a variety of laboratory tests. Longstanding field experience confirmed the results of theses tests.


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