ABB REL561 1MRK002496-AC REL561 1MRK002496-AC

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.

Although warning hazards are related to personal injury, it is necessary to understand

that under certain operational conditions, operation of damaged equipment may result

in degraded process performance leading to personal injury or death. Therefore,

comply fully with all warning and caution notices.

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 91).

Document conventions

A particular convention may not be used in this manual.

• Abbreviations and acronyms are spelled out in the glossary. The glossary also

contains definitions of important terms.

• Parameter names are shown in italics.

The function can be enabled and disabled with the Operation setting.

• Parameter values are indicated with quotation marks.

The corresponding parameter values are "On" and "Off".

• Input/output messages and monitored data names are shown in Courier font.