Standards Development

Scope

This standard defines the design/type tests, routine test, acceptance tests and classifications for Surge Arc Suppressor (SAS) devices, non-metal oxide arc suppressing device that consist of arc quenching mechanisms for overhead transmission and distribution lines of a.c. systems above 1 kV.

Purpose

The first applications of SASs were made in the 1990s in Japan and Russia. Since then, they have been applied in several countries under various descriptive names, such as CLG (Current Limiting Gap), and have become a popular choice for distribution networks due to their attractive lifecycle costs and their capability to withstand high charge transfer ratings on unshielded overhead lines. The number of such devices worldwide is estimated to be around 3 million units, mostly on networks up to 77kV, although some applications exist beyond that. They differ from EGLA (Externally Gapped Line Arresters as per IEC 60099-8) because they are not made of metal-oxide resistors. Nevertheless, they offer a follow current quenching capability that is verified in a similar manner as EGLAs. As SASs use a different technology than metal-oxide, they cannot be classified and standardized according to existing standards of TC37. For this reason, it is necessary to dedicate a specific standard to them.

SASs offer many advantages for improving lightning performance on overhead lines. Such applications are becoming more and more common as an effective way of improving power quality and continuity of services. Many countries are very affected by these problems when the unshielded distribution lines cross remote areas during certain periods of high keraunic intensity.

SASs have extremely high charge transfer ratings in comparison to Qrs ratings for metal-oxide line surge arresters. It makes them the ideal choice (for instance) for ungrounded system with high soil resistivity. SASs have proven to be a more compelling solution for some DSOs, such as in Malaysia, due to a certain number of issues with metal-oxide line surge arresters.

Some countries, such as Japan, also recommend the use of SASs as bird protection equipment. Indeed, when the conventional arcing horns of the insulator strings are replaced by SASs, the electrical hazard for the animals is reduced or even eliminated because the SASs behave as insulated horns.

SASs were introduced recently (2021) under the designation of CLGs in the CIGRE TECHNICAL BROCHURE 855 (Effectiveness of line surge arresters for lightning protection of overhead transmission lines) together with NGLA and EGLA as a Line Surge Arresters.

A standard already exists in China and several national specifications exist in several countries such as Japan. There is a need for standardization at the international level (IEC/IEEE) to incorporate industry standards that already apply to metal-oxide line surge arresters.

A new standard for SASs will find many analogies with the current EGLA standard (IEC 60099-8) and the future LSA standard (IEC/IEEE 60099-11) regarding terms and definitions and type testing.

A Technology & Product Explainer video is available here to facilitate understanding => https://youtu.be/9dCkTkwI5yc

In the technical literature, you might find different terminologies. It could be confusing but all of these terms refer to the same technology. Surge Arc Suppressors proposes to cover all these terminologies :

CLG – Current Limiting Gaps

FCIAH – Fault Current Interrupting Arcing Horn

s LLPD – Line Lightning Protection Devices

MCG – Multi-Chamber Gaps

MCA – Multi-Chamber Arresters

MLPD - Multi-series-gap Lightning Protection Device

LFA – Long Flashover Arresters