Electrical utilities and end users need power quality evaluation standards to protect electrical power systems from malfunctioning or failing. Power quality evaluation standards help electrical utilities prevent electrical disturbances from affecting the operation of equipment that end users and electrical utilities own. End users use power quality evaluation standards to prevent user-generated electrical disturbances from affecting the operation of equipment that end users and electrical utilities own.

EN 50160:2007 defines the limits within which voltage characteristics of electricity can remain normal operations over public distribution networks. The European Union is the leader in using EN 50160:2007 to implement supply quality standards. Several countries use EN 50160:2007 as the basis of their national regulations about supply quality.

EN 50160:2007 defines the following characteristics of a supply voltage:

  • Power frequency.
  • Magnitude of the supply voltage.
  • Supply voltage variations.
  • Rapid voltage changes and flickers.
  • Supply voltage dips.
  • Short interruptions of the supply voltage.
  • Long interruptions of the supply voltage.
  • Temporary power frequency overvoltages.
  • Transient overvoltages.
  • Supply voltage unbalance.
  • Harmonic voltage.
  • Interharmonic voltage.
  • Mains signaling voltage.

EN 50160:2007 specifies that each characteristic must not exceed defined limits for a specific period. For example, when you measure fundamental frequency over 10 seconds for electrical power systems with a synchronous connection to an interconnected electrical power system, 99.5% of the fundamental frequency measurements of a year must be within the range of 49.5 Hz to 50.5 Hz under normal operating conditions.