Siemens SIPROTEC 7SJ80

30 V and 60 V (for 64-1 VGND with a standard V
0
-connection) or 50 V and 100 V (for 64-1 VGND). Large
fault resistances may require higher sensitivity (i.e. a lower pickup setting).
With regard to a grounded system, a more sensitive (lower) pickup value may be set, but it must be above the
maximum anticipated displacement voltage during normal (unbalanced) system operation.
Pickup of just the voltage element may initiate time delayed tripping assumed that ground fault detection is
configured to perform tripping (address 3101 Sens. Gnd Fault = ON or ON with GF log) and moreover
address 3130 PU CRITERIA is configured Vgnd OR INs. The tripping delay is then set at address 3112
64-1 DELAY. It is important to note that the total tripping time consists of the displacement voltage meas-
urement time (about 50 ms) plus the pickup time delay (address 3111 T-DELAY Pickup) plus the tripping
time delay (address 3112 64-1 DELAY).
Direction Determination for cos-ϕ/ sin-ϕ
Addresses 3115 to 3126 are important for direction determination.
Address 3115 67Ns-2 DIRECT determines the direction of the definite high-set current element 50Ns-2 and
can be set to either Forward or Reverse or Non-Directional, i.e. to both directions. The direction of the
current element 50Ns-1 or or 51Ns can be set to Forward or Reverse or Non-Directional, i.e. to both
directions, at address 3122 67Ns-1 DIRECT..
Current value RELEASE DIRECT. (address 3123) is the release threshold for directional determination. It is
based on the current components which are perpendicular to the directional limit lines. The position of the
directional limit lines themselves are based on the settings entered at addresses 3124 and 3125.
The following applies to the determination of direction during ground faults: The pickup current 3Ι0 DIR.
(=RELEASE DIRECT. address 3123) must be set as high as possible to avoid false pickup of the device
provoked by asymmetrical currents in the system and by current transformers (especially in the Holmgreen-
connection).
If direction determination is used in conjunction with one of the current elements discussed above (50Ns-1
PICKUP, addresses 3117 ff, or 51Ns PICKUP, addresses 3119 ff), it is sensible to select a value for address
RELEASE DIRECT. that is lower than or equal to the above pickup value.
A corresponding message (reverse, forward, or undefined) is issued upon direction determination. To avoid
chatter for this message resulting from extremely varying ground connection currents, a dropout delay RESET
DELAY, entered at address 3126, is initiated when directional determination drops out, and the message is
held for this period of time.
When address 3124 PHI CORRECTION is set to 0.0°, in address 3125 the following signifies
•
MEAS. METHOD = COS φ
the resistive component of the ground current with respect to the displacement voltage is most relevant
for the current value RELEASE DIRECT. (3Ι0 DIR.),
MEAS. METHOD = SIN φ
the reactive (capacitive) component of the ground current with respect to the displacement voltage is
most relevant for the current value RELEASE DIRECT. (3Ι0 DIR.) (Figure 2-84).
Functions
2.12 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
SIPROTEC 4, 7SJ80, Manual 189
E50417-G1140-C343-A8, Edition 12.2017