Functions
2.14 Instantaneous High-Current Switch-onto-Fault Protection (SOTF)
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
292
Figure 2-147 Logic diagram of the high current switch on to fault protection
2.14.2 Setting Notes
General
A precondition for using the fast tripping function is that the configuration of the device functions (Section 2.1.1)
has been set at address 124 HS/SOTF-O/C = Enabled At address 2401 FCT HS/SOTF-O/C it can also be
switched ON or OFF.
I>>> Stage
The magnitude of fault current which leads to the pickup of the I>>> stage is set as I>>> in address 2404.
Choose a value which is high enough for the protection not to pick up on the RMS value of the inrush current
produced during the connection of the protected object. On the other hand, fault currents flowing through the
protected object do not need to be considered.
When using a PC and DIGSI for the parameterization, the values can be optionally entered as primary or sec-
ondary quantities. For settings with secondary values, the currents will be converted for the secondary side of
the current transformers.
At address 2406 CBaux for I>>>, you can specify whether only the switch position of the local circuit
breaker is checked to release the stage (local only) or also the switch position of the circuit breakers at the
other ends (local and rem.). If set to local and rem., the stage is active when the local end is energized
while the circuit breakers at all other terminals of the protected object are opened.
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