1MRS750915-MUM
REM 54_
27
Machine Terminal
Technical Reference Manual, General
5. Technical Description
5.1. Functional description
5.1.1. Functions of the machine terminal
The functions of REM 54_ machine 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 two subsets that correspond to different
functionality levels (refer to section “Ordering Information” on page 95).
5.1.1.1. Protection functions
Protection is one of the most important functions of the machine terminal. The
protection function blocks (e.g. NOC3Low) are independent of each other and have
their own setting groups, data recording, etc. The non-directional overcurrent
protection, for example, includes the three stages NOC3Low, NOC3High and
NOC3Inst, each with independent protection functions.
Either Rogowski coils or conventional current transformers can be used for
protection functions based on current measurement (overcurrent). Correspondingly,
voltage dividers or voltage transformers are used for protection functions based on
voltage measurement (overvoltage).
The protection function blocks are documented on the CD-ROM Technical
Descriptions of Functions.
Table 5.1.1.1-1 Protection functions available for REM 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
Diff3
a
High-impedance or flux-balance based differential protection for
generators and motors
Diff6G Stabilized three-phase differential protection for generators
DOC6Low
b
Three-phase directional O/C function, low-set stage I> ->
DOC6High
b
Three-phase directional O/C function, high-set stage I>> ->
DOC6Inst
b
Three-phase directional O/C function, instantaneous stage I>>> ->
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
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