GE UR Series C70 Instruction Manual page 279

5 SETTINGS
When fed from wye-connected VTs, thus function responds to phase-to-ground voltages. When fed from delta-connected
VTs, this function responds to the vector difference between the phase-to-phase voltages.
The function responds to true RMS voltages to account for effects of harmonics (harmonics impacting losses in the capaci-
tor, harmonics increasing peak values in the voltages compared with the filtered fundamental frequency magnitudes).
For more information refer to the Theory of Operation and Application of Settings chapters. The following settings are avail-
able for each bank phase overvoltage element.
• BANK OV 1 BUS SOURCE: This setting indicates the signal source that signifies the bus voltage of the capacitor
bank. The function uses this source as reference for per-unit (pu) settings of the pickup thresholds. The VT ratio and
secondary nominal voltage are set under the
• BANK OV 1 NTRL SOURCE: This setting indicates the signal source that signifies the neutral-point voltage of the
bank. The auxiliary voltage channel of this source is used, and must be labelled "Vn" under the VT setup menu. The
neutral point voltage is used only when the function is applied to an ungrounded bank, to derive the true voltage drop
across the capacitors. The VT ratio and secondary nominal voltage are set under the
AC INPUTS VOLTAGE BANK
• BANK OV 1 BANK GROUND: This setting indicates if the protected bank is grounded, ungrounded with the neutral
point voltage measured, and ungrounded without the neutral point voltage. The relay automatically compensates for
potentially different VT ratios and secondary voltages of the bus and neutral point voltages. The following table
explains the operating signals of the function based on the input signals available to the relay.
VT BANK CONFIGURATION
CONNECTION
GROUNDED
Wye Vop_A = VA
Vop_B = VB
Vop_C = VC
Delta Vop_A = (VCA – VAB) / 3
Vop_B = (VAB – VBC) / 3
Vop_C = (VBC – VCA) / 3
GE Multilin
Figure 5–74: BANK OVERVOLTAGE BASIC CONNECTIONS
SETTINGS
menu.
UNGROUNDED
Vop_A = VA – VX
Vop_B = VB – VX
Vop_C = VC – VX
C70 Capacitor Bank Protection and Control System
5.6 GROUPED ELEMENTS
Alternative: delta
connected VTs
C70 CAPACITOR BANK RELAY
Phase
BUS
VT Bank
SRC
NTRL
Aux VT
SRC
For ungrounded
banks only
834734A1.DWG
SYSTEM SETUP AC INPUTS
SETTINGS
UNGROUNDED W/O VN
Vop_A = (VCA – VAB) / 3
Vop_B = (VAB – VBC) / 3
Vop_C = (VBC – VCA) / 3
59B
menu.
VOLTAGE BANK
SYSTEM SETUP
5-155
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