I.S. TR 50422:2004

1 Background
  1.1 General
  1.2 Background
2 Application of the European Standard EN 50160
  2.1 Introduction
  2.2 Scope of the European Standard
  2.3 Definitions
  2.4 Groups of voltage characteristics
      2.4.1 Definite values
      2.4.2 Indicative values
  2.5 Voltage terminology
3 Description of main voltage characteristics
  3.1 Power frequency
  3.2 Magnitude of the supply voltage
  3.3 Supply voltage variations
  3.4 Rapid voltage changes
        3.4.1 Magnitude of rapid voltage changes
        3.4.2 Flicker severity
        3.4.3 Supply voltage dips
  3.5 Short and long interruptions of the supply voltage
  3.6 Temporary (power frequency) overvoltages between
       live conductors and earth
       3.6.1 LV distribution systems
       3.6.2 MV distribution systems
  3.7 Transient overvoltages between live conductors
       and earth
       3.7.1 LV distribution system
       3.7.2 MV distribution systems
  3.8 Supply voltage unbalance
  3.9 Harmonic voltage
  3.10 Interharmonic voltage
  3.11 Mains signalling voltage on the supply voltage
4 References

Covers several specific examples of exceptional conditions which are beyond the DNO's control and which can cause one or more of the characteristics to depart from the values given.