IEC 60099-8:2017,Surge arresters – Part 8: Metal-oxide surge arresters with external series gap (EGLA) for overhead transmission and distribution lines of a.c. systems above 1 kV.IEC 60099-8:2017 pdf free download.
IEC 60099-8:2017 is available as IEC 60099-8:2017 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 60099-8:2017 covers metal-oxide surge arresters with external series gap (externally gapped line arresters (EGLA)) that are applied on overhead transmission and distribution lines, only to protect insulator assemblies from lightning-caused flashovers. This document defines surge arresters to protect the insulator assembly from lightning-caused over-voltages only.
This part of IEC 60099 applies to the externally gapped line arrester (EGLA)
This type of surge arrester is connected directly in parallel with an insulator assembly. It comprises a series varistor un it (SVU),made up from non-linear metal-oxide resisto encapsulated in a polymer or porcelain housing, and an external series gap (see Figure 1).
The purpose of an EGLA is to protect the parallel-connected insulator assembly from lightning-caused over-voltages. The external series gap, therefore, should spark over only due to fast-front over-voltages.
EGLAs are classified by the ir nominal discharge currents and their high current impulse withstand capabilities as per Table 1,and they shall meet at least the test requirements and pteris tics specified in Table 3.