ABB RET670 - Page 603

The setting tMaxSynch is set to reset the operation of the synchronizing function if the
operation does not take place within this time. The setting must allow for the setting of
FreqDiffMin, which will decide how long it will take maximum to reach phase
equality. At the setting of 10 ms, the beat time is 100 seconds and the setting would
thus need to be at least tMinSynch plus 100 seconds. If the network frequencies are
expected to be outside the limits from the start, a margin needs to be added. A typical
setting is 600 seconds.
tMinSynch
The setting tMinSynch is set to limit the minimum time at which the synchronizing
closing attempt is given. The synchronizing function will not give a closing command
within this time, from when the synchronizing is started, even if a synchronizing
condition is fulfilled. A typical setting is 200 ms.
Synchrocheck settings
OperationSC
The OperationSC setting Off disables the synchrocheck function and sets the outputs
AUTOSYOK, MANSYOK, TSTAUTSY and TSTMANSY to low. With the setting
On, the function is in the service mode and the output signal depends on the input
conditions.
VHighBusSC and VHighLineSC
The voltage level settings must be chosen in relation to the bus or line network voltage.
The threshold voltages VHighBusSC and VHighLineSC have to be set lower than the
value at which the breaker is expected to close with the synchronism check. A typical
value can be 80% of the base voltages.
UDiffSC
The setting for voltage difference between line and bus in p.u, defined as (U-Bus/
UBaseBus) - (U-Line/UBaseLine).
FreqDiffM and FreqDiffA
The frequency difference level settings, FreqDiffM and FreqDiffA, are chosen
depending on network conditions. At steady conditions, a low frequency difference
setting is needed, where the FreqDiffM setting is used. For autoreclosing, a bigger
frequency difference setting is preferable, where the FreqDiffA setting is used. A
typical value for FreqDiffM can be10 mHz, and a typical value for FreqDiffA can be
100-200 mHz.
PhaseDiffM and PhaseDiffA
1MRK504116-UUS C Section 3
IED application
597
Application manual