Introduction
1-11
7SA6 Manual
C53000-G1176-C156-2
Time Delayed
Overcurrent
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
standards 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
transformer and circuit breaker (when the isolator switching status feed back is
available); particularly suited to sub-stations with 1
1
/
2
circuit breaker arrangements.
High Current Fast
Switch-on-to-Fault
Protection
• Fast tripping for switch-on-to-fault conditions;
• Selectable for manual closure or following each closure of the circuit breaker;
• With integrated line energization detection.
Sensitive Earth
Fault Detection
(optional)
For resonant-earthed or isolated systems with
• Detection of displacement voltage
• Determination of earth-faulted phases
• Sensitive determination of the earth fault direction
• Phase displacement correction for current transformers
Automatic
Reclosure
(optional)
• For reclosure after single-pole, three-pole or single and three-pole tripping;
• Single or multiple reclosure (up to 8 reclosure attempts);
• With separate action times for every reclosure attempt, optionally without action
times;
• With separate dead times after single-pole and three-pole tripping, separate for the
first four reclosure attempts;
• Controlled optionally by protection start with separate dead times after single, two
and three-pole starting
• Optionally with adaptive dead time, phase-to-phase voltage and reduced dead time
Synchronism and
Voltage Check
(Dead-line /
Dead-bus Check)
(optional)
• Checking synchronism conditions before reclosure after three-pole switching;
• Fast measuring of voltage difference U diff of the phase angle difference
ϕ diff and
the frequency difference f diff;
• Alternative check of dead-line / dead-bus before reclosure;
• Switching under asynchronous network conditions with advance calculation of the
synchro-time possible;
• Adjustable minimum and maximum voltage;
• Checking synchronism or dead-line / dead-bus also before manual closure of the
circuit breaker, with separate limit values;
• Measurement via transformer also possible;
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