Lightning current arresters in ac and dc power systems
The performance and operational behaviour of a surge protective device, connected to an ac power system, can be completely different from the performance and operational behaviour of the same surge protective device connected to a dc power system. Nowadays dc power systems are frequently used in industries such as photovoltaics, telecommunications and the railway industry. The operational behaviour of dc power systems can differ significantly from one specific application to another application. Since there are currently no test requirements for SPDs connected to dc power systems in the respective product standards, manufacturers have to prove that the performance of an SPD, connected to a specific dc power system, is suitable for that specific application and the SPD in question can perform safely and effectively.
- Lightning current arresters for low-voltage power systems are usually designed and tested only for use in ac power systems.
- No test procedures for the testing of SPDs connected to dc power systems are included in this IEC standard.
- Forcing an electric arc to make multiple bends inside a spark gap – increases the arc-burning voltage and increases the line follow current quenching capability –essential for quenching dc follow current.
Lightning current arresters in dc power supply systems
By H Heckler and T Rayner, Phoenix Contact
Electricity+Control, October 2012 (pages 16 – 23)
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