Voltage Sensing; Power System - GE 339 Instruction Manual

S2 SYSTEM SETUP

Voltage sensing

Power system

6–26
PATH:
SETPOINTS > S2 SYSTEM SETUP > VOLTAGE SENSING
VT CONNECTION
Range: Wye, Delta
Default: Wye
The 339 provides three-phase VT inputs. Select "Wye" connection, if phase-neutral
voltages are wired to the relay VT terminals. Select "Delta" connection, if phase-phase
voltages from Delta VT are connected to the three-phase VT terminals. See the VT
connections per the Typical Wiring Diagram in Chapter 2.
VT SECONDARY
Range: 50 V to 240 V
Default: 120 V
This setting defines the voltage across the VT secondary winding when nominal voltage
is applied to the primary. On a source of 13.8kV line-line voltage, with a VT ratio of
14400:120 V delta connection, the voltage to be entered is "115 V". For a Wye
connection, the voltage to be entered is 115/ √3 = 66 V.
VT RATIO
Range: 1.0:1 to 300.0:1
Default: 1:1
This setting defines the VT primary to secondary turns ratio. For a 14400: 120 VT, the
entry would be "120:1" (14400/120 = 120).
PATH: SETPOINTS > S2 SYSTEM SETUP > POWER SYSTEM
NOMINAL FREQUENCY
Range: 60 Hz, 50 Hz
Default: 60 Hz
Enter the nominal power system frequency. This value is used as a default to set the
optimal digital sampling rate.
SYSTEM ROTATION
Range: ABC, ACB,
Default: ABC
Enter the phase sequence of the power system.
339 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 6: SETPOINTS