Technical description
2 Protection functions
2.19 Synchrocheck (25)
VM259.EN007
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117
2.19.
Synchrocheck (25)
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, feeding side and reference. The reference
voltage used for sychrochecking is either phase-to-phase
voltage U
12
or phase-to-ground voltage U
L1
.
Setting parameters of synchrocheck stage SyC1 (25)
Parameter Values
Unit
Default
Description
Side
UL1/ULLy
UL1/ULNy
-
U12/ULLy
Voltage selection. The
used voltage reference is
selected with voltage
measurement mode from
the Scaling menu.
CBObj
Obj1
-
Obj1
NOTE!
The stage is always
using the object 1 for
syncrocheck.
SMode
Async;
Sync; Off
-
Sync
Synchrocheck mode.
Off = only voltage check
Async = the function
checks dU, df and dangle.
Furthermore, the
frequency slip, df,
determines the remaining
time for closing. This time
must be longer than ―CB
time‖.
Sync mode =
Synchronization is tried to
make exactly when angle
difference is zero. In this
mode df-setting should be
very small (<0.3Hz).