Siemens SIPROTEC 5 Manual page 388
Fault recorder, v7.50 and higher
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Also See for SIPROTEC 5:
- Manual (272 pages) ,
- Operation manual (218 pages) ,
- Technical data manual (129 pages)
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Supervision Functions
8.3 Supervision of the Secondary System
Logic
[locssumm-140611-01.tif, 3, en_US]
Figure 8-20
Slope of the Characteristic Curve
The Slope factor • Σ | I | part takes into account permissible current-proportional transformation errors of
the transformer, which can occur in the case of high short-circuit currents.
The Slope factor and Threshold parameters are used to set the fault-current limit (I
sum supervision. The device calculates this fault current limit with the formula:
I
= Threshold + Slope factor • Σ| I |
Fmax
The device uses the current inputs (IA, IB, IC and IN) to calculate:
•
The fault current IF = |IA + IB + IC + kl• IN|
•
The maximum current Σ| I | = | IA| + |IB| +| IC| + |kl• IN|
with k
taking into account a possible difference from the transformation ratio of a separated ground-current
I
transformer (I
), for example, cable type current transformer.
N
•
Transformation ratio of residual-current converter: Ratio
•
Transformation ratio of phase-current converter: Ratio
388
Logic Diagram of the Current-Sum Supervision
N
ph
SIPROTEC 5, Fault Recorder, Manual
C53000-G5040-C018-5, Edition 11.2017
) for the current-
Fmax
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