Allen-Bradley Rockwell Automation 857 User Manual page 116

3-66
Protection Functions
857-UM001A-EN-P – July 2009
Figure 3.32 – Principle of the Synchrocheck Function
Please note that the control pulse of the selected object should be
long enough. For example, if the voltages are in opposite direction,
the synchronizing conditions are met after several seconds.
Figure 3.33 – Block diagram of the synchrocheck and the controlling object
Please note that the wiring of the secondary circuits of voltage
transformers to the device terminal depends on the selected voltage
measuring mode.
Table 3.40 – Voltage measurement modes for synchrocheck function
Voltage
Terminals
input
U X1:11-12
a
U X1:13-14
b
U X1:17-18
c
Number of
synchrocheck stages
Availability of U and
0
directional I stages
0
Power measurement
Signals in mode Signals in mode
"1LL+U /LLy" "2LL/LLy"
0
U U
12 12
U U
12y 23
U U
0 12y
1 1
Yes No
1-phase power, 3-phase power,
symmetrical loads unsymmetrical
loads
Signals in mode
"LL/LLy/LLz"
U
12
U
12y
U
23z
2
No
1-phase power,
symmetrical loads