GE Multilin 850

CHAPTER 4: SETPOINTS CONTROL
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL 4–351
INITIATION
Range: Off, Underfreq 1(X) OP, or FreqRate1(X) DWN OP
Default: Off
The setpoint selects the FlexLogic operand that initiates the UF Restore scheme;
typically the operate signals from Underfrequency or Frequency Rate of Change
functions.
MINIMUM VOLTAGE
Range: 0.000 to 1.250 x VT in steps of 0.001 x VT
Default: 0.900 x VT
The setting sets the minimum voltage for Underfrequency Restoration element
operation specified per times VT.
FAST PATH:
If the initial frequency is measured from a 3-phase delta connected VT, the positive
sequence voltage is used as the supervision voltage. In such condition, the true supervision
level is internally changed to 1/sqrt(3) of the user setting since the base of VT here is the
phase-phase voltage.
FAST PATH:
The Minimum Voltage setpoint for the selected UF Restore element applies to the same
voltage input as the one programmed in the menu of the element selected for UF Restore
Initiate setpoint.
MINIMUM FREQUENCY
Range: 20.00 to 65.00 Hz in steps of 0.01 Hz
Default: 59.90 Hz
The setting sets the minimum frequency to allow the Underfrequency Restoration
element to operate.
FAST PATH:
The voltage and frequency used here should be associated with the initiation signal. For
example, if the UF restore scheme is triggered by Underfreq 1 OP, the voltage and
frequency values in the ‘Underfrequency 1’ element should be applied.
RESTORE DELAY
Range: 0.000 to 6000.000 s in steps of 0.001 s
Default: 10.000 s
The setting provides a definite restore time delay. Instantaneous operation is selected
by a restore time delay setting of 0.000 s.
INCOMPLETE SEQUENCE TIME
Range: 1 to 10000 min in steps of 1 min
Default: 100 min
This setting provides a definite reset time delay.
SYNCHROCHECK SUPERVISION
Range: Bypass, Sync1 Close Perm
Default: Bypass
The setpoint selects Synchrocheck supervision. The closing signal (for output #2 only)
from the UF Restore function can be supervised by the Synchrocheck function. The
Synchrocheck function has to be enabled and set accordingly. For applications where
Synchrocheck and/or dead source check is not needed, supervision can be bypassed. If
the Synchrocheck function is not selected in the order code, this setting would be hidden
and defaulted to Bypass.
FAST PATH:
If the supervision is not bypassed and UF Restore is applied for an application where the
breaker is located on radial feeders, or line is powered by one source only, the DEAD
SOURCE PERM setpoint from the Synchrocheck menu must not be disabled.