ABB Relion 650 Series Applications Manual page 108

Section 8
Voltage protection
ANSI07000190 V1 EN-US
Figure 36: Ground fault in Non-effectively grounded systems
8.3.3.3 Direct grounded system
In direct grounded systems, an ground fault on one phase indicates a voltage collapse in that
phase. The two healthy phases will have normal phase-to-ground voltages. The residual sum will
have the same value as the remaining phase-to-ground voltage. See
102
ANSI07000190-1-en.vsd
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1MRK 505 287-UUS B
GUID-EA622F55-7978-4D1C-9AF7-2BAB5628070A v7
Figure 37.
Busbar protection REB650
Application manual