BS EN 60255-127:2014

1 Scope and object
2 Normative references
3 Terms and definitions
4 Specification of the function
5 Performance specification
6 Functional test methodology
7 Documentation requirements
Annex A (informative) - Reset time determination
        for relays with trip output only
Bibliography
Annex ZA (normative) - Normative references to
         international publications with their
         corresponding European publications

Specifies minimum requirements for over/under voltage relays. And it includes specification of the protection function, measurement characteristics and time delay characteristics.

This part of IEC 60255 specifies minimum requirements for over/under voltage relays. The standard includes specification of the protection function, measurement characteristics and time delay characteristics. This standard defines the influencing factors that affect the accuracy under steady state conditions and performance characteristics during dynamic conditions. The test methodologies for verifying performance characteristics and accuracy are also included in this standard. The over/under voltage functions covered by this standard are as follows: IEEE/ANSI C37.2
Function numbers IEC 61850-7-4
Logical nodes Phase undervoltage protection 27 PTUV Positive sequence undervoltage protection 27D PTUV Phase overvoltage protection 59 PTOV Residual/zero-sequence overvoltage protection 59N/59G PTOV Negative sequence/ unbalance overvoltage protection 47 PTOV The general requirements for measuring relays and protection equipment are specified in IEC 60255-1.