Siemens SIPROTEC 7SJ62 Manual page 228

Functions
2.12 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
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
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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or pickup of the 50Ns-2 element or pickup of the 50Ns-1 or 51Ns
0
C53000-G1140-C207-2, Release date 01.2008
SIPROTEC, 7SJ62/64, Manual