ABB Relion REQ650, Applications Manual

Page: 202 / 340

With the setting On , the function is in service and the output signal depends on the
input conditions.
UDiffSC
Setting for voltage difference between line and bus in p.u. This setting in p.u is defined
as (measured U-Bus/UBase for bus according to
GblBaseSelBus ) - (measured U-Line/
UBase for line according to GblBaseSelLine ). 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
PhaseDiffA setting is limited by the
PhaseDiffM setting.
tSCM and tSCA
The purpose of the timer delay settings, tSCM and tSCA , is to ensure that the
synchrocheck 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 synchrocheck 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 operation time delay setting is preferable, where the tSCA
setting is used. A typical value for the tSCM may be 1 second and a typical value for the
tSCA may be 0.1 second.
Energizing check settings
AutoEnerg and ManEnerg
Two different settings can be used for automatic and manual closing of the circuit
breaker. The settings for each of them are:
• Off , the energizing function is disabled.
• DLLB , Dead Line Live Bus: the line voltage is below 40% of the line base voltage
UBase according to the setting GblBaseSelLine about the Global Base Value
Section 10
1MRK 505 291-UEN A
Control
196
Application manual