Introduction
1.3 Characteristics
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
29
Monitoring Functions
• Availability of the device is greatly increased because of self-monitoring of the internal measurement circuits,
power supply, hardware, and software;
• Current transformer and voltage transformer secondary circuits are monitored using summation and sym-
metry check techniques
• Trip circuit monitoring;
• Phase rotation check.
Ground Fault Detection 50N(s), 51N(s), 67N(s), 59N/64
• Displacement voltage is measured or calculated from the three phase voltages;
• Determination of a faulty phase on ungrounded or grounded networks;
• Two-element Ground Fault Detection: 50Ns-1 and 50Ns-2;
• High sensitivity (as low as 1 mA);
• Overcurrent element with definite time or inverse time delay;
• one user-defined, two logarithmic inverse current/time elements and one V0-I0-ϕ characteristic for 51 and
51N are available;
• Direction determination with zero-sequence quantities (I
0
, V
0
), wattmetric ground fault direction determina-
tion;
• Any element can be set as directional or non-directional — forward sensing directional, or reverse sensing
directional;
• Directional characteristic can be adjustable;
• Optionally applicable as additional ground fault protection.
Intermittent Ground Fault Protection
• Detects and accumulates intermittent ground faults;
• Tripping after configurable total time.
Automatic Reclosing 79
• Single-shot or multi-shot;
• With separate dead times for the first and all succeeding shots;
• Protective elements that initiate automatic reclosing are selectable. The choices can be different for phase
faults and ground faults;
• Different programs for phase and ground faults;
• Interaction to time overcurrent protection element and ground fault elements. They can be blocked in de-
pendence of the reclosing cycle or released instantaneously;
• Synchronous reclosing is possible (only for 7SJ623, 7SJ624 and 7SJ64) in combination with the integrated
synchronizing feature.
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