Mounting and Commissioning
3.3 Commissioning
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
556
At least one stage of the earth fault protection must be set to be directional (address 31xx of the earth fault
protection). The pickup threshold of this stage must be below the load current flowing on the line; if necessary
the pickup threshold must be reduced. The parameters that have been changed, must be noted.
Figure 3-35
Polarity check of
I
4
, example with earth current from a power transformer star point
After switching the test source on and off again, the direction indication must be checked: The fault log must at
least contain the messages
„EF Pickup“
and
„EF forward“
. If the directional pickup is missing, a connec-
tion error of the earth current connection
I
4
is present. If the wrong direction is indicated, the earth current con-
nection
I
4
has a swapped polarity. In the latter case, the connection must be corrected after the test source has
been switched off. The measurements must then be repeated.
If the pickup alarm is missing altogether, this may be due to the fact that the test current is too small.
Note
If parameters were changed for this test, they must be returned to their original state after completion of the
test !
