CEI EN 60255-121 : 2014

FOREWORD
1. Scope
2. Normative references
3. Terms and definitions
4. Specification of the function
5. Performance specifications
6. Functional tests
7. Documentation requirements
Annex A (informative) - Impedance characteristics
Annex B (informative) - Informative guide for the
        behaviour of timers in distance protection
        zones for evolving faults
Annex C (normative) - Setting example
Annex D (normative) - Calculation of mean,
        median and mode
Annex E (informative) - CT saturation and
        influence on the performance of
        distance Relays
Annex F (informative) - Informative guide for
        testing distance relays based on CT
        requirements specification
Annex G (informative) Informative guide for
        dimensioning of CTs for distance protection
Annex H (normative) - Calculation of relay settings
        based on generic point P expressed in terms
        of voltage and current
Annex I (normative) - Ramping methods for testing
        the basic characteristic accuracy
Annex J (normative) - Definition of fault inception
        angle
Annex K (normative) - Capacitive voltage instrument
        transformer model
Annex ZA (normative) - Normative references to
         international publications with their corresponding
         European publications

Describes the 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.