ABB RET 541 Product Manual page 61

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