IEC 60099-5:2000 pdf free download

IEC 60099-5:2000 pdf free download Surge arresters – Part 5: Selection and application recommendations
1.1 Scope
This part of IEC 60099 provides recommendations for the selection and application of surge arresters to be used in three-phase systems with nominal voltages above 1 kV. It applies to non-linear resistor type gapped surge arresters as defined in IEC 60099-1 and to gapless metal-oxide surge arresters as defined in IEC 60099-4.
1.2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of IEC 60099. For dated references, subsequent amend- ments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of IEC 60099 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of IEC and ISO maintain registers of currently valid International Standards.
IEC 60071 -1 :1 993, Insulation co-ordination – Part 1 : Definitions, principles and rules
IEC 60071 -2:1 976, Insulation co-ordination – Part 2: Application guide
NOTE The third edition of this standard is presently under revision.
IEC 60099-1 :1 991 , Surge arresters – Part 1 : Non-linear resistor type gapped surge arresters for a.c. systems
IEC 60099-3:1 990, Surge arresters – Part 3: Artificial pollution testing of surge arresters
NOTE This Technical Report applies to gapped surge arresters according to IEC 60099-1 .
IEC 60099-4:1 991 , Surge arresters – Part 4: Metal-oxide surge arresters without gaps for a.c.systems
IEC 60507:1 991 , Artificial pollution tests on high-voltage insulators to be used on a.c. systems
IEC 6081 5:1 986, Guide for the selection of insulators in respect of polluted conditions
1.3 General principles for the application of surge arresters
IEC 60071 -1 specifies withstand voltages for two ranges of highest voltages for equipment:
– range I: above 1 kV to 245 kV included
– range II: above 245 kV
For range I systems containing overhead lines, the main risk to equipment arises from induced and direct lightning strokes to the connected overhead lines. In cable systems not connected to overhead lines, overvoltages due to faults or switching operations are most likely to occur. In rare cases, however, lightning induced overvoltages may also be generated. In systems of range II, in addition to range I factors, switching overvoltages become important, increasing with higher system voltages. Overvoltages may cause flashovers and serious damage to the equipment and thereby jeopardize the supply of power to users. It is essential to prevent this by the proper co-ordination of surge arresters with the insulation. It is, therefore, recommended to use surge arresters if there are possibilities of lightning overvoltages or high switching overvoltages which may be dangerous to the equipment.