ABB REQ650 - Direct Earthed System

IEC07000190 V1 EN
Figure 74: Earth fault in Non-effectively earthed systems
7.3.3.3 Direct earthed system
In direct earthed systems, an earth fault on one phase indicates a voltage collapse in
that phase. The two healthy phases will have normal phase-to-earth voltages. The
residual sum will have the same value as the remaining phase-to-earth voltage. See
Figure 75.
1MRK 505 291-UEN A Section 7
Voltage protection
163
Application manual