MT 4 - TC 37/MT 4

IEC 60099-6: 2019 applies to non-linear metal-oxide resistor type surge arresters with spark gaps designed to limit voltage surges on AC power circuits with system voltages Us above 1 kV up to and including 52 kV. This document basically applies to all metal-oxide distribution class surge arresters with internal series and/or parallel gaps and housed in either porcelain or polymeric housings. This second edition cancels and replaces the first edition published in 2002. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) A new concept of arrester classification and energy withstand testing was introduced: the line discharge classification was replaced by a classification based on repetitive charge transfer rating (Qrs) and thermal charge transfer rating (Qth). The new concept clearly differentiates between impulse and thermal energy handling capability, which is reflected in the requirements as well as in the related test procedures.
b) Power-frequency voltage versus time tests – with and without prior duty – were introduced as type tests.
c) Requirements and tests on disconnectors were added.
d) Definitions for new terms have been added.
e) Clause 10 contains particular requirements for polymer-housed surge arresters. These are indicated in the form of replacements, additions or amendments to the original clauses or subclauses concerned.
Keywords: testing of metal-oxide surge arresters

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. Therefore, and since metal-oxide resistors are not permanently connected to the line, the following items are not considered for this document:
- 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.
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. Designs with the EGLA's external series gap installed in parallel to an insulator are not covered by this document. This second edition cancels and replaces the first edition published in 2011. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
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
Keywords: externally gapped line arresters (EGLA), lightning-caused over-voltages

IEC 60099-4:2014 applies to non-linear metal-oxide resistor type surge arresters without spark gaps designed to limit voltage surges on a.c. power circuits with Us above 1 kV. This third edition cancels and replaces the second edition published in 2009. This edition constitutes a technical revision. The numerous changes between the second and third editions are listed in the Foreward of the document. Keywords: testing of gapless metal-oxide surge arresters for a.c.power systems

IEC 60099-9:2014 applies to non-linear metal-oxide resistor type surge arresters without spark gaps designed to limit overvoltages in HVDC converter stations of two terminal, multiterminal and back-to-back type up to and including an operating voltage of 1 100 kV. The standard applies in general to porcelain-housed and polymer-housed type arresters but also to gas-insulated metal enclosed arresters (GIS-arresters) solely used as d.c. bus and d.c. line/cable arresters. Arresters for voltage source converters are not covered. Arresters applied on the a.c. systems at the converter station and subjected to power-frequency voltage of 50 or 60 Hz principally without harmonics are tested as per IEC 60099-4. The arresters on a.c.-filters are tested according to this standard. Keywords: testing of gapless metal-oxide surge arrestors for HVDC converter stations

IEC 60099-8:2011 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 standard defines surge arresters to protect the insulator assembly from lightning-caused overvoltages only. Designs with the EGLA's external series gap installed in parallel to an insulator are not covered by this standard.