BS EN IEC 60099-8:2018

What is BS EN IEC 60099-8 – Externally gapped line arresters (EGLA) about?

BS EN IEC 60099-8 is the eighth part of the IEC 60099 multi-series that discusses surge arresters.

BS EN IEC 60099-8 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.

BS EN IEC 60099-8 defines surge arresters to protect the insulator assembly from lightning-caused over-voltages only.

Considering the particular design concept and the special application on overhead transmission and distribution lines, some unique requirements and tests are introduced, such as the verification test for coordination between insulator withstand and EGLA protective level, the follow current interrupting test, mechanical load tests, etc.

Note1: Since metal-oxide resistors are not permanently connected to the line, the following items are not considered for BS EN IEC 60099-8:

• Switching impulse spark-over voltage
• Residual voltage at steep current and switching current impulse
• Thermal stability
• Long-duration current impulse withstand duty
• Power-frequency voltage versus time characteristics of an arrester
• Disconnector test
• Aging duties by power-frequency voltage

Note2: Designs with the EGLA's external series gap installed in parallel to an insulator are not covered by BS EN IEC 60099-8.

Who is BS EN IEC 60099-8 – Externally gapped line arresters (EGLA) for?

BS EN IEC 60099-8 on metal-oxide surge arresters is useful for:

• Energy infrastructure companies
• Private or public electricity supply departments
• Testing authorities

Why should you use BS EN IEC 60099-8 – Externally gapped line arresters (EGLA)?

EGLA protect power lines from disruptions like lightning and switching overvoltage events and increases the availability of ultra-high voltage (UHV) electricity networks. If the EGLA fails to perform its task due to some malfunctions or defects it could affect the local grid’s electricity supply. 

BS EN IEC 60099-8 identifies and classifies the EGLAs based on their discharge capacities. BS EN IEC 60099-8 provides you with ideal service conditions for these EGLAs where they would perform as intended without any disruptions. BS EN IEC 60099-8 specifies a series of test methods to verify the performance capacities like lightning discharge capability, mechanical performance, weather ageing of SVU etc. These tests help you to verify the quality, durability and longevity of EGLAs.

Overall, the guidelines of BS EN IEC 60099-8 help you to create a more efficient electricity transmission network by helping you to create better quality EGLAs and thus, reducing disruptions in your energy supply system.

What’s changed since the last update?

BS EN IEC 60099-8:2018 replaces BS EN IEC 60099-8:2011. BS EN IEC 60099-8:2018 constitutes a technical revision. BS EN IEC 60099-8:2018includes the following significant technical changes with respect to BS EN IEC 60099-8:2018:

• The Lightning discharge capability test has been completely re-written and re-named to Test to verify the repetitive charge transfer rating, Qrs with lightning discharges to reflect changes introduced in IEC 60099-4 Ed. 3 (2014) regarding new methods for rating the energy and charge handling capability of metal-oxide arresters. In addition to testing to evaluate the performance of the MO resistors, procedures for evaluating the performance of the EGLA series gaps have been introduced.
• Omissions from Ed. 1 of this standard have been included, notably an RIV test and a
• means for determining the thermal time constant of the SUV portion of the EGLA.
• Definitions for new terms have been added
• A number of NOTES in Ed. 1 have been converted to normative requirements