ABB RET 54 Series - 5 Technical Description; Functional Description; Functions of the Transformer Terminal; Protection Functions

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1MRS755225
Transformer Terminal
Technical Reference Manual, General
RET 54_
5. Technical Description
5.1. Functional description
5.1.1. Functions of the transformer terminal
The functions of the RET 54_ transformer terminal are categorized as:
• Protection functions
• measurement functions
• control functions
• condition monitoring functions
• communication functions
• general functions
• standard functions
The functions are further divided to three subsets that correspond to different
functionality levels (refer to Section “Ordering Information” on page 103).
5.1.1.1. Protection functions
Protection is one of the most important functions of the RET 54_ transformer
terminal. The protection function blocks (e.g. NOC3Low) are independent of each
other and have e.g. their own setting groups and data recording.
The protection function blocks are documented on the CD-ROM “Technical
Descriptions of Functions” (refer to “Related documents” on page 9).
Table 5.1.1.1-1 Protection functions available for the RET 54_
Function Description
DEF2Low Directional earth-fault protection, low-set stage
DEF2High Directional earth-fault protection, high-set stage
DEF2Inst Directional earth-fault protection, instantaneous stage
Diff6T Stabilized three-phase differential protection for transformers
DOC6Low Three-phase directional overcurrent protection, low-set stage
DOC6High Three-phase directional overcurrent protection, high-set stage
DOC6Inst Three-phase directional overcurrent protection, instantaneous stage
Freq1St1 Underfrequency or overfrequency protection, stage 1
Freq1St2 Underfrequency or overfrequency protection, stage 2
Freq1St3 Underfrequency or overfrequency protection, stage 3
Freq1St4 Underfrequency or overfrequency protection, stage 4
Freq1St5 Underfrequency or overfrequency protection, stage 5
FuseFail Fuse failure supervision
Inrush3 Three-phase transformer inrush and motor start-up current detector
NEF1Low Non-directional earth-fault protection, low-set stage
NEF1High Non-directional earth-fault protection, high-set stage
NEF1Inst Non-directional earth-fault protection, instantaneous stage
NOC3Low Three-phase non-directional overcurrent protection, low-set stage
NOC3LowB Three-phase non-directional overcurrent protection, low-set stage B
NOC3High Three-phase non-directional overcurrent protection, high-set stage
NOC3Inst Three-phase non-directional overcurrent protection, instantaneous stage