IEC 61643-12:2008

FOREWORD
0 Introduction
  0.1 General
  0.2 Keys to understanding the structure of this standard
1 Scope
2 Normative references
3 Terms, definitions and abbreviated terms
  3.1 Terms and definitions
  3.2 List of abbreviations and acronyms used in this standard
4 Systems and equipment to be protected
  4.1 Low-voltage power distribution systems
  4.2 Characteristics of the equipment to be protected
5 Surge protective devices
  5.1 Basic functions of SPDs
  5.2 Additional requirements
  5.3 Classification of SPDs
  5.4 Characteristics of SPDs
  5.5 Additional information on characteristics of SPDs
6 Application of SPDs in low-voltage power distribution
  systems
  6.1 Installation and its effect on the protection given
      by SPDs
  6.2 Selection of SPD
  6.3 Characteristics of auxiliary devices
7 Risk analysis
Annex A (informative) Typical information given with
        inquiries and tenders and explanation of
        testing procedures
  A.1 Information given with inquiries
  A.2 Information given with tender
  A.3 Explanation of testing procedures used in IEC 61643-1
Annex B (informative) Examples of relationship between
        U[c] and the nominal voltage used in some systems
        and example of relationship between U[p] and U[c]
        for ZnO varistor
  B.1 Relationship between U[c] and the nominal voltage of
      the system
  B.2 Relationship between U[p] and U[c] for a ZnO varistor
Annex C (informative) Environment - Surge voltages in LV
        systems
  C.1 General
  C.2 Lightning overvoltages
  C.3 Switching overvoltages
Annex D (informative) Partial lightning current calculations
Annex E (informative) TOV in the low-voltage system due
        to faults between high-voltage systems and earth
  E.1 General
  E.2 Example of a TT system - Calculation of the possible
      temporary overvoltages
  E.3 Values of the temporary overvoltages according to
      IEC 60364-4-44
  E.4 Values of the temporary overvoltages for the US TN
      C-S system
Annex F (informative) Coordination rules and principles
  F.1 General
  F.2 Analytical studies: simple case of the coordination of
      two ZnO varistor based SPDs
  F.3 Analytical study: case of coordination between a
      gap-based SPD and a ZnO varistor based SPD
  F.4 Analytical study: general coordination of two SPDs
  F.5 Let-through energy (LTE) method
Annex G (informative) Examples of application
  G.1 Domestic application
  G.2 Industrial application
  G.3 Presence of a lightning protection system
Annex H (informative) Examples of application of the
        risk analysis
Annex I (informative) System stresses
  I.1 Lightning overvoltages and currents [4.1.1]
  I.2 Switching overvoltages [4.1.2]
  I.3 Temporary overvoltages U[TOV] [4.1.3]
Annex J (informative) Criteria for selection of SPDs
  J.1 U[T] temporary overvoltage characteristic [5.5.1.2]
  J.2 SPD failure modes [5.5.4]
Annex K (informative) Application of SPDs
  K.1 Location and protection given by SPDs [6.1]
  K.2 Selection of SPDs
Annex L (informative) Risk analysis
  L.1 Group A - Environmental
  L.2 Group B - Equipment and facilities
  L.3 Group C - Economics and service interruption
  L.4 Group D - Safety
  L.5 Group E - Cost of protection
Annex M (informative) Immunity vs. insulation withstand
Annex N (informative) Examples of SPD installation in power
        distribution boards in some countries
Annex O (informative) Coordination when equipment has
        both signalling and power terminals
Annex P (informative) Short circuit backup protection and
        surge withstand
  P.1 Introduction
  P.2 Information single shot 8/20 and 10/350 fuses withstand
  P.3 Fuse Influencing factors (reduction) for preconditioning
      and operating duty test
  P.4 Specific examples with estimated range of factors for
      reduction of single shot fuse withstand
Bibliography

IEC 61643-12:2008 describes the principles for selection, operation, location and coordination of SPDs to be connected to 50 Hz to 60 Hz a.c. and to d.c. power circuits and equipment rated up to 1 000 V r.m.s. or 1 500 V d.c. Specific change with respect to the previous edition is the incorporation of Amendment 1, which was not published separately due to the number of changes and pages.