1 Scope
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.