Synchrocheck Protection (25) - Allen-Bradley Rockwell Automation 857 User Manual

Synchrocheck Protection
(25)
Table 3.37 – Measured and recorded values of df/dt stage
Parameter
Measured f
value
df/dt
Recorded SCntr
values
TCntr
Flt
EDly
The device includes a function that will check synchronism when the
circuit-breaker is closed. The function will monitor voltage
amplitude, frequency and phase angle difference between two
voltages. Since there are two stages available, it is possible to
monitor three voltages. The voltages can be busbar and line or
busbar and busbar (bus coupler).
The synchrocheck causes that the normal measuring modes cannot
be used. Therefore, "2LL/LLy", "1LL+U
voltage measuring mode must be selected to enable synchrocheck
function. If "2LL/LLy"- or "1LL+U
stage is available. The "LL/LLy/LLz"-mode enables using two
stages.
The voltage used for sychrochecking is always phase-to-phase
voltage U . The sychrocheck stage 1 compares U
12
always. The compared voltages for the stage 2 can be selected.
Table 3.38 – Setting Parameters of Synchrocheck Stages SyC1, SyC2 (25)
Parameter Values
Side U12/U12y;
U12/U12z;
U12y/U12z
CBObj Obj1-Obj6
Protection Functions
Value Unit
Hz Frequency
Hz/s Frequency rate of change
- Start counter (Start) reading
- Trip counter (Trip) reading
%Hz/s Max rate of change fault
value
% Elapsed time as compared
to the set operating time,
100% = tripping
/LLy" or "LL/LLy/LLz"
0
/LLy"-mode is selected, one
0
12
Unit Default
- U12/U12z Voltage selection. The stage 1
has fixed voltages U12/U12y.
- Obj1 The selected object for CB
control. The synchrocheck
closing command will use the
closing command of the
selected object.
NOTE! The stage 1 is always
using the object 1. The stage 2
can use objects 2-6.
3-63
Description
with U
12y
Description
857-UM001A-EN-P – July 2009