IEC 60099-5-2000 pdf free download – Surge arresters – Part 5: Selection and application recommendations.
1.1Scope
This part of lEC 60o99 provides recommendations for the selection and application of surgearresters to be used in three-phase systems with nominal voltages above i kV. lt applies tonon-linear resistor type gapped surge arresters as defined in iEC 60099-1 and to gaplessmetal-oxide surge arresters as defined in lEC 60099-4.
1.2Normative references
The following normative documents contain provisions which，through reference in this text,constitute provisions of this part of lEC 60099. For dated references，subsequent amend-ments to， or revisions of， any of these publications do not apply. However，parties toagreements based on this part of lEC 60o99 are encouraged to investigate the possibility ofapplying the most recent editions of the normative documents indicated below.For undatedreferences, the latest edition of the normative document referred to applies. Members of lECand lso maintain registers of currently valid lnternational Standards.
IEC 60071-1:1993,Insulation co-ordination – Part 1 : Definitions, principles and rules
IEC60071-2:1976,Insulation co-ordination – Part 2: Application guide
NOTE The third edition of this standard is presently under revision.
IEC 60099-1:1991,Surge arresters – Part 1: Non-linear resistor type gapped surge arrestersfor a.c. systems
IEC 60099-3:1990，Surge arresters – Part 3:Artificial pollution testing of surge arresters
NOTE This Technical Report applies to gapped surge arresters according to lEC 60099-1.
IEC 60099-4:1991, Surge arresters – Part 4: Metal-oxide surge arresters without gaps for a.c.systems
IEC 60507:1991，Artificial pollution tests on high-voltage insulators to be used on a.c.systems
IEC 60815:1986,Guide for the selection of insulators in respect of polluted conditions
1.3General 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 lI: 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.
These surge arresters should constitute a reliable part of the system. They are designed to withstand the voltages and the resulting currents through them with a sufficiently high reliability taking into account pollution and other site matters. In each system such voltage stresses are (see IEC 60071 -1 ):
– operating voltage;
– temporary overvoltages;
– slow-front overvoltages;
– fast-front overvoltages;
where the slow-front overvoltages due to switching are of particular importance for arresters protecting range II equipment.
As a general principle, the best protection of equipment and high surge arrester rated voltages are contradicting requirements. Thus the selection of an adequate arrester consti- tutes an optimization process, which has to consider a great number of system and equipment parameters.IEC 60099-5 pdf download.