Functions
2.11 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A5, Release date 11.2012
196
Figure 2-70 Logic diagram for U0-/I0 -ϕ measurement, part 2
2.11.3 Ground Fault Location
Application Example
Directional determination may often be used to locate ground faults. In radial systems, locating the ground fault
is relatively simple. Since all feeders from a common bus (Figure 2-71) deliver a capacitive charging current,
nearly the total ground fault current of the system is available at the measuring point of the faulty line in the
ungrounded system. In the resonant grounded system it is the residual wattmetric current of the Petersen coil
that flows via the measuring point. Therefore, on the faulty cables a clear "forward" decision is made whereas
in other feeders either "reverse" direction is sent back or no measurement is carried out in case ground current
is too low. Definitely the faulty line can be determined clearly.
Figure 2-71 Location of ground faults in a radial network
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