Siemens 7SJ85 - Application and Setting Notes

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Figure 6-270 Behavior under Different Fault Conditions
Functional Measured Values
Measured Value Description
(_:306) I REF,operate Operate quantity of the restricted ground-fault protection from
the angle criterion
(_:307) I Angle,REF Stabilizing value (angle) of the restricted ground-fault protection
from the angle criterion
(_:311) I REF,Trip operate Operate quantity of the restricted ground-fault protection when
OFF
(_:312) I angle,REF operate Stabilizing value of the restricted ground-fault protection when
OFF
(_:301) I diff. Differential current
(_:302) I restr. Restraint current
You will find the measured values for the Restricted ground-fault protection under the following device
menu entries:
•
Main menu → Measurements → function → Function values → 87N REF
Application and Setting Notes
i
i
NOTE
The following conditions must be observed when setting the threshold values:
Threshold value ≥ max {0.05 I/Irated,S ; 0.05 I/Irated,S * I
prim transf. max
/ I
rated, protected object
}
Threshold value ≤ min {2.00 I/Irated,S ; 100.00 I/Irated,S * I
prim transf. max
/ I
rated, protected object
}
The value 0.05 I/Irated,S is the minimum possible setting value and 2.00 I/Irated,S the
maximum possible. I
prim,transf. max
is the largest transformer current and I
rated,protected object
the protected object
rated current. 100.00 I/Irated,S is the upper measurement limit.
If otherwise, it could happen that there is chattering of the pickup indication, the minimum threshold limit
is lifted. The maximum limit on the other hand is corrected downward, if the exceeding current otherwise
through the magnitude scaling must be so large, that it would already be outside of the measuring range
of the transformer.
The adaptation of the setting limits is done automatically. In addition, a setting is prevented outside of
these limits.
6.43.4
Protection and Automation Functions
6.43 Restricted Ground-Fault Protection
868 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017