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
Summary of Contents for RET 541
Page 1: ...Transformer Terminal Product Guide RET 541 RET 543 RET 545 ...
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