Functions
2.12 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
228
Logic
The following figure illustrates the activation criteria of the sensitive ground fault protection. The operational
mode of the ground fault detection can be set under address
3101
.
If set to
ON
, tripping is possible and a fault log is generated.
If set to
ON with GF log
, tripping is possible, a fault log and a ground fault log are generated.
If set to
Alarm Only
, tripping is not possible and only a ground fault log is generated.
The pickup of the displacement voltage V
0
or pickup of the 50Ns-2 element or pickup of the 50Ns-1 or 51Ns
element start the ground fault recording. As the pickup of the element drops out, fault recording is terminated
(see logic diagrams 2-85 and 2-86).
The entire function can be blocked under the following conditions:
• A binary input is set,
• the Fuse Failure Monitor or the voltage transformer protection breaker pick up.
Switching off or blocking means that measurement is deactivated. Therefore, time delays and pickup messages
are reset.
All elements can be blocked individually via binary inputs. In this case pickup and, if possible, direction and
grounded phase will still be reported, however, tripping does not take place since the time elements are
blocked.
Figure 2-84
Activation of the sensitive ground fault detection for V0/I0-
ϕ
measurement
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