GE Multilin G650 Manual page 223

5.5 CONTROL ELEMENTS
5.5.4.1 VOLTAGE INPUTS
In order to perform the synchronism check function, the G650 uses only one voltage from each end of the breaker. Voltage
values to be compared must be on the same basis, either phase-to-phase or phase-to-ground voltage; they must be the
same at both ends of the breaker; it is not possible to compare a phase-to-ground voltage at one end with a phase-to-
phase voltage at the other end.
Additionally, if on one end, three voltages have been connected, the necessary voltage on the other end for Function 25 will
only be single-phase voltage. If there is only one voltage (either phase-to-phase or phase-to-ground) at both ends of the
breaker, this must be from the same phase in both cases.
The selection of voltage values to be used by the synchronism element is made in the relay General settings:
V1 is the line voltage, selectable from the relay voltage channels, using the "Frequency Reference" setting at
Setpoint > System Setup > General settings > Frequency Reference. (Please refer to the voltage correspondence
Table 5–80:)
V2 is the busbar voltage measured at the auxiliary voltage input (terminals A11-A12). To enable the busbar voltage
metering in the relay, it is required to select VX in the Auxiliary Voltage setting at Setpoint > System Setup >
General settings > Auxiliary Voltage.
The voltage correspondence is detailed in the following table:
Table 5–80: VOLTAGE CORRESPONDENCE ELEMENT 25
Setpoint>System Setup>General settings>Frequency Reference
Voltage selection for element 25 of G650
Setpoint>System Setup>General settings>Phase VT Connection=WYE
Phase-to-ground voltage connection.(Wye connection)
5
Setpoint>System Setup>General settings>Phase VT Connection=DELTA
Phase-to-phase voltage connection.(Delta connection).
Setpoint>System Setup>General settings>
Auxiliary Voltage=Vx
Setpoint > System Setup > General settings > Auxiliary Voltage setting must be set to Vx, in order to monitor auxiliary
voltage instead of Vn (neutral voltage, coming from an open delta connection).
5.5.4.2 APPLICATION
Even if the application range of the G650 is quite wide and the element can be used in distribution lines at any voltage level,
it must be taken into account that it is a three-pole tripping relay, designed for managing a single breaker. This is why
G650 is not suitable for one and a half breaker configurations, or ring configurations where a transmission line or feeder
has two breakers.
5-80 G650 Generator Protection & Control System
5 SETTINGS
VOLTAGE CORRESPONDENCE
V V V
I II III
V V V
a-g b-g c-g
V V V
a-b b-c c-a
V
x
GEK-113285A