Siemens 7SC80 Manual page 256

Functions
2.13 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
Tripping Area
The U0/I0-ϕ characteristic is illustrated as a sector in the U0/I0 phasor diagram (see
corresponds to the tripping area. If the cursor of the ground current is in this sector, the function picks up.
The tripping area is defined via several parameters: Via the angle ϕ (parameter 3154 50Ns-1 Phi or 3151
50Ns-2 Phi), the center of the zone with reference to the displacement voltage V
(parameter 3155 50Ns-1 DeltaPhi or 3152 50Ns-2 DeltaPhi), the zone is extended to both sides of the
center.
The zone is further limited downwards by minimum values of the displacement voltage and ground current.
These settable threshold values must be exceeded in order to be picked up.
Negative angle settings turn the tripping area in the "inductiv" direction, i.e. ground current inductive
compared to ground voltage.
[enel-character, 1, en_US]
Figure 2-88
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
The entire function can be blocked under the following conditions:
•
A binary input is set,
•
the voltage transformer monitor or the voltage transformer protection breaker picks up.
Switching off or blocking means that measurement is deactivated. Therefore, time delays and pickup
messages are reset.
256
Tripping range of V0-Ι0-φ characteristic
0
Figure 2-90 and Figure
or pickup of the 50Ns-2 element or pickup of the 50Ns-1 or 51Ns
2-91).
Figure 2-88). This sector
is set. Via the angle Δϕ
0
SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017