GE 850 Instruction Manual page 510

SYNCHROCHECK (25)
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MAX VOLT DIFFERENCE
Range: 10 to 600000 V in steps of 1 V
Default: 2000 V
The setpoint selects the maximum primary voltage difference in volts between the two
sources. A primary voltage magnitude difference between the two input voltages below
this value is within the permissible limit for synchronism.
MAX FREQ HYSTERESIS
Range: 0.01 to 0.10 Hz in steps of 0.01 Hz
Default: 0.05 Hz
The setpoint specifies the required hysteresis for the maximum frequency difference
condition. The condition becomes satisfied when the frequency difference becomes
lower than SYNC1 MAX FREQ DIFFERENCE. Once the Synchrocheck element has
operated, the frequency difference must increase above the SYNC1 MAX FREQ
DIFFERENCE + SYNC1 MAX FREQ HYSTERESIS sum to drop out (assuming the other two
conditions, voltage and angle, remain satisfied).
DEAD SOURCE PERM
Range: Disabled, LB & DL, DB & LL, DB & DL, DB OR DL, DB XOR DL
Default: Disabled
The setpoint selects the combination of dead and live sources that bypass the
synchronism check function and permit the breaker to be closed when one or both of
the two voltages (Bus Voltage or/and Line Voltage) are below the maximum voltage
threshold. A dead or live source is declared by monitoring the voltage level. Six options
are available.
The voltage levels that determine whether a source is dead or live are configurable in the
four setpoints following this one.
The DEAD SOURCE PERMISSION range is as follows:
"Disabled": Dead source permissive is disabled.
"LB & DL": Live Bus AND Dead Line."DB & LL": Dead Bus AND Live Line.
"DB & DL": Dead Bus AND Dead Line.
"DB OR DL": Dead Bus OR Dead Line.
"DB XOR DL": Dead Bus XOR Dead Line (one source is Dead and one is Live).
For an application where the breaker is located on radial feeders, or line is powered by one
source only, the DEAD SOURCE PERM setpoint shall not be disabled.
LIVE BUS VOLTS MIN
Range: 0.00 to 1.50 x VT in steps of 0.01 x VT
Default: 0.80 x VT
The setpoint establishes a minimum voltage magnitude for the Bus Voltage. Above this
magnitude, the Bus Voltage input used for Synchrocheck is considered "Live" or
energized.
LIVE LINE VOLTS MIN
Range: 0.00 to 1.50 x VT in steps of 0.01 x VT
Default: 0.80 x VT
The setpoint establishes a minimum voltage magnitude for the Line Voltage. Above this
magnitude, the Line Voltage input used for Synchrocheck is considered "Live" or
energized.
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 8: CONTROL