IEC 60099-8:2011 pdf 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
1 Scope
This part of IEC 60099 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. Therefore, and since the metal-oxide resistors are not permanently
connected to the line, the following items are not considered for this standard:
• switching impulse sparkover 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 standard.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60060-1 :1 989, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60060-2:1 994, High-voltage test techniques – Part 2: Measuring systems
IEC 60068-2-1 1 :1 981 , Environmental testing – Part 2: Tests. Test kA: Salt mist
IEC 60068-2-1 4:2009, Environmental testing – Part 2-14: Tests – Test N: Change of
temperature
IEC 60099-4:2009, Surge arresters – Part 4: Metal-oxide surge arresters without gaps for a.c.
systems
IEC 60270:2000, High-voltage test techniques – Partial discharge measurements
IEC 60507:1 991 , Artificial pollution tests on high-voltage insulators to be used on a.c.
systems
IEC/TS 6081 5-1 :2008, Selection and dimensioning of high-voltage insulators intended for use
in polluted conditions – Part 1: Definitions, information and general principles
IEC 6221 7:2005, Polymeric insulators for indoor and outdoor use with a nominal voltage
> 1 000 V – General definitions, test methods and acceptance criteria
ISO 3274, Geometric product specifications (GPS) – Surface texture: Profile method –
Nominal characteristics of contact (stylus) instruments
ISO 4287, Geometrical Product Specifications (GPS) – Surface texture: Profile method –
Terms, definitions and surface texture parameters
ISO 4892-1 , Plastics – Methods of exposure to laboratory light sources – Part 1: General
Guidance
ISO 4892-2, Plastics – Methods of exposure to laboratory light sources – Part 2: Xenon-arc
sources
ISO 4892-3, Plastics – Methods of exposure to laboratory light sources – Part 3: Fluorescent
UV lamps
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 externally gapped line arrester
EGLA
arrester designed for installation on overhead lines to protect an insulator assembly from
lightning-caused fast-front overvoltages only
NOTE This is accomplished by rising the sparkover level of the external series gap to a level that isolates the arrester from power-frequency overvoltages and from the worst case slow-front overvoltages due to switching and fault events expected on the line to which it is applied.
3.2 series varistor unit
SVU
non-linear metal-oxide resistor part, contained in a housing, which must be connected with an
external series gap to construct the complete arrester
NOTE The series varistor unit may include several units.
3.3 section of an EGLA
complete, suitably assembled part of a complete EGLA necessary to represent the behaviour
of a complete EGLA with respect to a particular test
3.4 section of an SVU
complete, suitably assembled part of an SVU unit necessary to represent the behaviour of an
SVU with respect to a particular test
IEC 60099-8:2011 pdf 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
