[lo-esd-erd-anr-20101117, 2, en_US]
Figure 2-12
Ground current differential protection pickup, grounded system
You will find the logic diagram for the general pickup of the differential protection and the differential protec-
tion tripping in Section
2.2.5 Differential Protection Pickup Logic and Tripping Logic
Setting Notes
General
The operating mode of the ground differential protection depends on the neutral point treatment in the
protected zone. In grounded systems, address 207
SystemStarpoint
must be set to
Grounded
.
The ground differential protection can be switched
ON
or
OFF
at address 1221
87N L: Protect.
. This
requires the ground differential protection to be set to
Enabled
at address 112
87 DIFF.PROTEC.
. The
setting
Alarm only
is only relevant for ground fault detection in resonant-grounded or isolated systems.
If a device is switched off or if the ground differential protection is disabled or blocked in a device, calculation
of measured values becomes impossible. The entire ground differential protection system of both ends is
blocked in this case.
Pickup Value Ground Current Differential Protection
The current sensitivity is set at address 1222
87N L: I-DIFF>
. It is determined by the entire current flowing
into a protected zone in case of a fault. This is the total fault current regardless of how it is distributed
between the ends of the protected object.
This pickup value must be set to a value that is higher than the total steady-state quadrature-axis component
of current of the protected object. For cables and long overhead lines, the charging current has to be consid-
ered in particular. It is calculated from the operational capacitance (see Section
2.2.3.2
Functions
2.2 Phase Comparison Protection and Ground Differential Protection
SIPROTEC 4, 7SD80, Manual
57
E50417-G1100-C474-A2, Edition 02.2018
Summary of Contents for SIPROTEC 4 7SD80
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