Siemens siprotec 7SA522, User Manual

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Introduction
1-7
7SA522 Manual
C53000-G1176-C119-2
1.4 Scope of Functions
The numerical Distance Protection SIPROTEC
®
7SA522 has the following functions:
Distance Protection
•
Protection for all types of short-circuit in systems with earthed star point;
•
selectable polygonal tripping characteristic or MHO–circle characteristic;
•
reliable distinction between load and short-circuit conditions, also on long, heavily
loaded lines;
•
high sensitivity in the case of a weakly loaded system, extreme stability against load
jumps and power swings;
•
six measuring systems for each distance zone (full scheme design);
•
six distance zones, selectable as forward, reverse or non-directional reaching, one
may be graded as an overreaching zone;
•
nine time stages for the distance zones;
•
optimum adaption to the line parameters by means of the tripping characteristic with
diverse configuration parameters and “load trapezoid” (elimination of the possible
load impedances);
•
Direction determination (with polygon) or polarisation (with MHO–circle) is done
with unfaulted loop (quadrature) voltages and voltage memory, thereby achieving
unlimited directional sensitivity, and not affected by capacitive voltage transformer
transients;
•
current transformer saturation detection and compensation;
•
compensation against the influence of a parallel line is possible;
•
shortest tripping time is approx. 15 ms (f
N
= 60 Hz) or 17 ms (f
N
= 50 Hz);
•
phase segregated tripping (in conjunction with single-pole or single- and three-pole
auto-reclosure) is possible;
•
non delayed tripping following switch on to fault is possible.
•
two sets of zero sequence compensation factors.
Power Swing
Suppplement
•
Power swing detection with dZ/dt–measurement with three measuring systems;
•
power swing detection up to a maximum of 7 Hz swing frequency;
•
in service also during single-pole dead times ;
•
settable power swing programs;
•
prevention of undesired tripping by the distance protection during power swings;
•
tripping for out-of-step conditions can also be configured.
Teleprotection
Supplement can be configured to various schemes for:
•
Permissive Underreach (PUTT);
•
Direct (underreach) Transfer Trip;
•
Permissive Overreach Transfer Trip (POTT);
•
Unblocking with overreach zone;