ABB REC 561 - Application; Design; Three-Phase Front Logic

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Function:
1 Application
The tripping logic in REx 5xx protection, control and monitoring termi-
nals offers two options:
• Three-phase tripping, available as a basic function in all 500 series
terminals of REx 5xx type.
• Single-phase tripping available as a basic or optional function,
dependent on type of terminal. For details refer to the ordering par-
ticulars. The logic also issues a three-phase tripping command when
phase selection within the operating protection function is not possi-
ble, or when external conditions request three-phase tripping.
You can select the operating mode (exclusively three-phase, or single and/
or three-phase) under the menu below only, when the single-phase trip-
ping logic is included in the terminal:
Settings
Functions
Group n
Trip
You can always switch off the operation of the tripping logic and thus dis-
able the terminal's tripping function.
2Design
The function consists of three basic logic parts:
• A three-phase front logic that is activated when the terminal is pro-
vided with a three-phase tripping function only. Or when the termi-
nal with the single and/or three-phase tripping logic is set to a three-
phase operating mode.
• A single-phase front logic that is activated when the terminal is pro-
vided with a single and/or three-phase tripping function, and the ter-
minal is set to a single-phase tripping mode.
• The tripping logic circuits.
2.1 Three-phase front
logic
Fig. 1 shows a simplified block diagram of a three-phase front logic. The
external phase-selective trip signals are:
• TRIP-EXTL1
• TRIP-EXTL2
• TRIP-EXTL3
When any of these three signals obtains logical 1, all three-phase-related,
tripping signals appear:
•L1TRIP
•L2TRIP
•L3TRIP
5
Tripping logic
1MRK 580 120-XEN
Version 1.0-00
October 1996
Basic