ABB 650 series Applications Manual page 114

Section 8
Control
108
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. Manual closing is
normally under more stable conditions and 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
tSCM can be 1 second and a typical value for tSCA can be 0.1 seconds.
Energizingcheck 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 set value of
ULowLineEnerg and the bus voltage is above set value of UHighBusEnerg.
• DBLL, Dead Bus Live Line, the bus voltage is below set value of
ULowBusEnerg and the line voltage is above set value of UHighLineEnerg.
• Both, energizing can be done in both directions, DLLB or DBLL.
ManEnergDBDL
If the parameter is set to On, manual closing is also enabled when both line voltage
and bus voltage are below ULowLineEnerg and ULowBusEnerg respectively, and
ManEnerg is set to DLLB, DBLL or Both.
UHighBusEnerg and UHighLineEnerg
The voltage level settings must be chosen in relation to the bus or line network
voltage. The threshold voltages UHighBusEnerg and UHighLineEnerg have to be
set lower than the value at which the network is considered to be energized. A
typical value can be 80% of the base voltages.
ULowBusEnerg and ULowLineEnerg
The threshold voltages ULowBusEnerg and ULowLineEnerg, have to be set to a
value greater than the value where the network is considered not to be energized. A
typical value can be 40% of the base voltages.
A disconnected line can have a considerable potential due to, for
instance, induction from a line running in parallel, or by being fed
1MRK 511 423-UEN A
Bay control REC650 2.2 IEC
Application manual