Direct Earthed System - ABB REC670 Applications Manual

1MRK 511 401-UEN A
9.3.3.5
Bay control REC670 2.2 IEC
Application manual
IEC07000190-2-en.vsd
IEC07000190 V2 EN-US
Figure 95: Earth fault in Non-effectively earthed systems

Direct earthed system

In direct earthed systems, an earth fault on one phase is indicated by voltage
collapse in that phase. The other healthy phase will still have normal phase-to-earth
voltage. The residual sum will have the same value as the remaining phase-to-earth
voltage, which is shown in Figure 96.
IEC07000189 V2 EN-US
Figure 96: Earth fault in Direct earthed system
Voltage protection
GUID-EA622F55-7978-4D1C-9AF7-2BAB5628070A v8
IEC07000189-2-en.vsd
Section 9
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