51N
Three phase CT
summated
WYE/DELTA, DELTA/WYE or
WYE/WYE transformer
en05000491_ansi.vsd
ANSI05000491 V1 EN-US
Figure 184: Residual overcurrent protection application on an isolated transformer
winding
In the calculation of the fault current fed to the protection, at different ground faults,
are highly dependent on the positive and zero sequence source impedances, as well as
the division of residual current in the network. Ground-fault current calculations are
necessary for the setting.
Setting of step 1
SEMOD55591-35 v5
One requirement is that ground faults at the busbar, where the transformer winding is
connected, shall be detected. Therefore a fault calculation as shown in Figure
185 is
made.
Section 9 1MRK 502 071-UUS A
Current protection
374 Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062
Application manual
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