Introduction
1-8 7SA522 Manual
C53000-G1176-C119-2
• Blocking;
• All teleprotection schemes are applicable to 2- and 3- terminal lines;
• Transfer of phase-segregated transmission signals possible;
• User specific applications can be implemented by way of the integrated CFC-Logic.
Earth Fault
Protection
• Earth fault overcurrent protection, with a maximum of three definite time stages
(DT) and one inverse time stage (IDMT) for high resistance earth faults in earthed
systems;
• for the IDMT protection a selection of various characteristics based on several
standards is possible;
• high sensitivity (depending on the version from 3 mA is possible);
• phase current stabilization against error currents during current transformer satura-
tion;
• inrush stabilization with second harmonic;
• each stage can be set to be non-directional or directional in the forward or reverse
direction;
• direction determination with zero sequence system quantities (I
0
, U
0
), with zero se-
quence current and transformer star-point current (I
0
, I
Y
). or with negative sequence
system quantities (I
2
, U
2
);
• one or more stages may function in conjunction with a signal transmission supple-
ment;
• non-delayed tripping after switch on to fault with any stage is possible.
Tripping/Echo at
Line Ends with No
or Weak Infeed
• possible in conjunction with teleprotection schemes;
• allows fast tripping at both line ends, even if there is no or only weak infeed available
at one line end;
• phase segregated tripping is possible.
External Direct and
Remote Tripping
• tripping at the local line end from an external device via a binary input;
• tripping of the remote line end by internal protection functions or an external device
via a binary input (with teleprotection);
Time Delayed Over-
current Protection
• selectable as emergency function in the case of measured voltage failure, or as
back up function independent of the measured voltage;
• maximally two definite time stages (DT) and one inverse time stage (IDMT), each
for phase currents and earth current;
• for IDMT protection a selection from various characteristics based on several stand-
ards is possible;
• blocking options e.g. for reverse interlocking with any stage;
• non-delayed tripping in the case of switching onto a fault with any stage is possible;
• stub protection: additional stage for fast tripping of faults between the current trans-
former and circuit breaker (when the isolator switching status feed back is avail-
able); particularly suited to sub-stations with 1
1
/
2
circuit breaker arrangements.
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