ABB RET 543 - Page 61

Transformer Terminal RET 541, RET 543, RET 545
1MRS755543
61
Application selection tables for RET 541, RET 543 and RET 545
functions
Table 30: Protection functions
Types of fault IEEE Device No. IEC Symbol Protection function Function block
code
Differential
protection
87T 3I>, 3I>> Stabilized and
instantaneous differential
protection for
transformers
Diff6T
Short circuit and
overcurrent
51 3I> Three-phase non-
directional overcurrent,
low-set stage
NOC3Low
51 3I> Three-phase non-
directional overcurrent,
low-set stage
NOC3LowB
50/51/51B 3I>> Three-phase non-
directional overcurrent,
high-set stage
NOC3High
50/51B 3I>>> Three-phase non-
directional overcurrent,
instantaneous stage
NOC3Inst
67 3I> Three-phase directional
o/c, low-set stage
DOC6Low
67 3I>> Three-phase directional
o/c, high-set stage
DOC6High
67 3I>>> Three-phase directional
o/c, instantaneous stage
DOC6Inst
Underimpedance 21 Z< Three-phase
underimpedance,low-set
stage
UI6Low
21 Z<< Three-phase
underimpedance, high-
set stage
UI6High
Earth fault 51N Io>/SEF Non-directional earth-
fault, low-set stage (or
SEF = sensitive earth-
fault protection)
NEF1Low
50N/51N Io>> Non-directional earth-
fault, high-set stage
NEF1High
50N Io>>> Non-directional earth-
fault, instantaneous stage
NEF1Inst
67N/51N Io>/SEF Directional earth-fault,
low-set stage (or SEF =
sensitive earth-fault
protection)
DEF2Low
67N Io>> Directional earth-fault,
high-set stage
DEF2High
67N Io>>> Directional earth-fault,
instantaneous stage
DEF2Inst
59N Uo> Residual overvoltage,
low-set stage
ROV1Low
59N Uo>> Residual overvoltage,
high-set stage
ROV1High
59N Uo>>> Residual overvoltage,
instantaneous stage
ROV1Inst
87N Io> High-impedance based
restricted earth-fault
protection
REF1A