Electricity + Control January 2017

EARTHING + LIGHTNING PROTECTION

Isolated LPS

Non-isolated LPS

Conclusion Solar power generation systems are an integral part of today‘s elec- trical systems. They should be equipped with adequate structural lightning protection systems, lightning current arresters and surge arresters, thereby ensuring long-term faultless operation of these sources of electricity. References [1] IEC 62305: 2010. Protection against lightning: Part 2. Risk Manage- ment. [2] IEC 62305: 2010. Protection against lightning: Part 3. Physical damage and life hazard. Trevor Manas started his lightning protection career at Pontins in 1991 as an installation technician, learning the ropes by working on various sites and doing physical installations. Within two years, he was promoted to a sales engineer position, where he was involved in site assessments, soil resistivity surveys and compiling quotations. In 1996, Trevor was promoted to the position of director and was in charge of ensuring the company`s compliance with the earthing and lightning protection codes of practice. In 1999, Trevor became the managing director of Pontins. In 2013, Pontins formed a partnership with DEHN Africa. Enquiries: Email trevor@pontins.co.za

Structures with external lightning protection and insufficient separation distances Lightning protection systems where adequate separation distances cannot be maintained, should be protected as follows: • LPS in accordance with lightning protection level • Surge protection by means of Class 1 lightning arresters and Class 2 and 3 surge arresters • Equipotential bonding by means of 16 mm² copper conductors or 50 mm² aluminium conductors When the correct separation distances cannot be establishment the PV systems are vulnerable to partial lightning currents, therefore the protection of inverters and data systems is done by means of Class 1 lightning arresters and not Class 2 surge arresters. In accordance with Supplement 5 of IEC 62305-3 [2] all of the PV lines entering the building from the outside (i.e. roof) must be protected by means of Class 1 lightning current arresters. In many cases, rooftop PV systems are installed on top of steel roofs, here the separation distances cannot be maintained due to the type of structure. In all cases where the separation distance cannot be maintained, then all of the metal components of the PV system must bonded directly onto the external lightning protection. It is still imperative that an air termination system be installed to protect the PV system fromdirect lightning strikes in order to provide a controlled interception and dissipation of the lightning current.

January ‘17 Electricity+Control

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