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2 Functions
2.12.6 Setting Notes
General Settings
209
Figure 2-74
Determination of the ground fault location basing on directional indicators in the
meshed system
The operating mode of the protective function is configured at address 131 Sens.
Gnd Fault (see Section 2.1.1). If address Sens. Gnd Fault = Definite Time,
then only the settings for the definite-time elements are available. If the setting is
Sens. Gnd Fault = Log. inverse A, a logarithmic inverse characteristic is avail-
able. If the setting is Sens. Gnd Fault = Log. Inverse B, a logarithmic inverse
characteristic with knee point is active. Alternatively, user-defined characteristic can
be used when setting Sens. Gnd Fault = User Defined PU. The superimposed
high-set element 50Ns-2 is available in all these cases. If the function is not required,
Disabled is set.
Address 213 VT Connect. 3ph specifies how the voltage transformers are connect-
ed (phase-ground or phase-phase). Furthermore, adaption factor Vph / Vdelta for
displacement voltage are properly set in address 206, primary and secondary nominal
transformer current in the ground path are properly set in addresses 217 and 218.
Sensitive ground fault detection may be switched ON or OFF or to Alarm Only in
address 3101 Sens. Gnd Fault. If sensitive ground fault protection is switched ON,
both tripping and message reporting is possible.
The ground fault is detected and reported only when the displacement voltage was
present for at least the time T-DELAY Pickup (address 3111).
Address 3130 PU CRITERIA specifies whether ground fault detection is enabled only
for pickups of V
and I
0
Ns
up (Vgnd OR
INs).
A two-stage current/time characteristic may be set at addresses 3113 through 3120.
Each of these elements may be directional or non-directional. These elements operate
with the ground current magnitude. They only make sense where the magnitude of the
ground current and maybe the direction can be used to specify the ground fault. This
may be the case on grounded systems (solid or low-resistant) or on electrical ma-
chines which are directly connected to the busbar of an ungrounded power system,
when in case of a network ground fault the machine supplies only a negligible ground
fault current across the measurement location, which must be situated between the
machine terminals and the network, whereas in case of a machine ground fault the
total ground fault current produced by the total network is available.
(Vgnd AND INs) or as soon as one of the two has picked
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
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