ABB REC650 Applications Manual page 202

Section 10
Control
196
The tMinSynch is set to limit the minimum time at which 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.
Typical setting is 200 ms.
Synchrocheck settings
OperationSC
The OperationSC setting Off disables the synchronsim check function and sets the outputs
AUTOSYOK, MANSYOK, TSTAUTSY and TSTMANSY to low.
With the setting Enabled, the function is in service and the output signal depends on the
input conditions.
VDiffSC
Setting for voltage difference between line and bus in p.u. This setting in p.u is defined as
(measured V-Bus/VBase for bus according toGblBaseSelBus) - (measured V-Line/VBase
for line according toGblBaseSelLine). A typical value for the voltage difference can be
15%.
FreqDiffM and FreqDiffA
The frequency difference level settings, FreqDiffM and FreqDiffA, shall be chosen
depending on the condition in the network. At steady conditions a low frequency
difference setting is needed, where the FreqDiffM setting is used. For auto-reclosing a
bigger frequency difference setting is preferable, where the FreqDiffA setting is used. A
typical value for the FreqDiffM can 10 mHz and a typical value for the FreqDiffA can be
100-200 mHz, when the synchronizing function is not used.
PhaseDiffM and PhaseDiffA
The phase angle difference level settings, PhaseDiffM and PhaseDiffA, shall also be
chosen depending on conditions in the network. The phase angle setting must be chosen
to allow closing under maximum load. A typical maximum value in heavy-loaded
networks can be 45 degrees whereas in most networks the maximum occurring angle is
below 25 degrees. The setting of PhaseDiffAsetting is limited by the PhaseDiffM setting.
tSCM and tSCA
The purpose of the timer delay settings, tSCM and tSCA, is to ensure that the synchronism
check conditions remains constant and that the situation is not due to a temporary
interference. Should the conditions not persist for the specified time, the delay timer is
reset and the procedure is restarted when the conditions are fulfilled again. Circuit breaker
closing is thus not permitted until the synchronism check situation has remained constant
throughout the set delay setting time. Under stable conditions a longer operation time
delay setting is needed, where the tSCM setting is used. During auto-reclosing a shorter
1MRK 511 286-UUS A
Application manual