GE Multilin G650 Manual page 225

5.5 CONTROL ELEMENTS
This time is considered if the relative slip is higher than 5 mHz; in this case, an anticipative algorithm is
executed to calculate the closing signal with the necessary advance for the breaker effective Closing to be
produced when voltages are in phase. In case the frequency slip is high (higher than 5 Hz) and it is not
possible to obtain a closing in phase, the used algorithm ensures that the voltage difference in the moment
of the closing is lower than the set voltage (Max Voltage Difference).
Note: Take into account that the value of related settings "Frequency Slip (Max Freq Difference)" multiplied by
"Breaker Closing time (Time)" must no be higher than 1. If that value is higher, that means that is necessary more than
one cycle to perform a close signal. In that case the relay will give the close signal only in the remain time. This function
depend on the voltage difference, the angle difference, the frequency difference and the synchronism time to perform a
close signal:
Angle = 360 x Time x Max Freq Difference < 360º and Time x Max Freq Difference < 1
Closing permission logic settings:
In case that the voltage at one or both ends of the breaker is null, the synchronism element cannot establish the necessary
parameters to give closing conditions, and therefore it does not issue synchronism permission. For those situations where
the user wants to enable the closing permission in a condition of loss of one or both voltages at both ends of the breaker,
G650 elements incorporate closing permission logics for the cases of: dead line-dead bus, live line-dead bus and dead line-
live bus.
Dead line- Dead Bus Function permission (DL-DB Function): Enabling this Function allows issuing a
Closing permission signal in dead line and dead bus Condition (without voltage at both sides of the breaker).
Live line- Dead Bus Function permission (LL-DB Function): Enabling this Function allows to issue a
Closing permission signal in live line and dead bus Condition (without voltage at the sides of the breaker that
corresponds to the busbar voltage)
Dead line- Live Bus Function permission (DL-LB Function): Enabling this Function allows issuing a
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Closing permission signal in live line and dead bus Condition (without voltage at the sides of the breaker that
corresponds to the line voltage).
Snapshot event: The snapshot event setting enables or disables the snapshot event generation for this element.
5-82 G650 Generator Protection & Control System
5 SETTINGS
GEK-113285A