Three Independent Stages; Setting Groups - Allen-Bradley Rockwell Automation 857 User Manual

3-54
Protection Functions
857-UM001A-EN-P – July 2009
U = max(U , U , U )
LLmax 12
dead band
U< setting
B
block limit
A
U< under-voltage state
Figure 3.27 – Under voltage state and block limit

Three independent stages

There are three separately adjustable stages: U<, U<< and U<<<.
All these stages can be configured for definite time (DT) operation
characteristic.

Setting groups

There are two settings groups available for all stages. Switching
between setting groups can be controlled by digital inputs, virtual
inputs (mimic display, communication, logic) and manually.
Table 3.30 – Parameters of the under voltage stages U<, U<<, U<<< (27)
Parameter Value
Status -
Blocked
Start
Trip
SCntr
TCntr
SetGrp 1 or 2
SGrpDI
-
DIx
VIx
LEDx
VOx
23 31
E
C
D
F
G
Unit Description
Current status of the stage
Cumulative start counter
Cumulative trip counter
Active setting group
Digital signal to select the active
setting group
None
Digital input
Virtual input
LED indicator signal
Virtual output
UunderSelfBlocking
I
K
H
J
time
Note
F
F
C
C
Set
Set