IEC 61865:2001

FOREWORD
INTRODUCTION
1 Scope
2 Normative references
3 Terms, definitions and symbols
  3.1 Definitions
  3.2 Symbols
4 Approach used to derive the electrical distance
5 Overvoltages
  5.1 Classification of overvoltages
  5.2 Temporary overvoltages
  5.3 Slow-front overvoltages
  5.4 Fast-front overvoltages
6 Required withstand voltage of the air gap
  6.1 General
  6.2 Calculation of the required withstand voltage
7 Calculation of the distance associated with the
  overvoltages
Annex A (informative) Relationship between U(50) and the
        gap length, d
Annex B (informative) Example of the calculation of the
        electrical component
Bibliography

Gives guidance for the calculation of electrical distances between live and earthed parts required to prevent air-gap breakdown which may endanger members of the public who legitimately come close to live parts. Applies only to overhead lines designed to operate at more than 45 kV phase-to-phase a.c. It manages the electrical component of distances between conductors and movable objects - vehicles on the ground, vessels on water, persons on top of objects or on the ground, wildlife on the ground (but not airborne), etc.