Over deze norm
NEN-EN-IEC 60255-121 specifies minimum requirements for functional and performance evaluation of distance protection function typically used in, but not limited to, line applications for effectively earthed, three-phase power systems. This standard also defines how to document and publish performance tests. This standard covers distance protection function whose operating characteristic can be defined on an impedance plane and includes specification of the protection function, measurement characteristics, phase selection, directionality, starting and time delay characteristics. The test methodologies for verifying performance characteristics and accuracy are included in this standard. The standard defines the influencing factors that affect the accuracy under steady state conditions and performance characteristics during dynamic conditions. It also includes the instrument transformer requirements for the protection function.
||Meetrelais en beveiligingsmaterieel - Deel 121: Functionele eisen voor veiligheid op afstand
||Measuring relays and protection equipment - Part 121: Functional requirements for distance protection