Siemens siprotec 7SA522 - Page 29

Introduction
1-97SA522 Manual
C53000-G1176-C119-2
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.
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
Synchronism and
voltage check
(dead-line / dead-
bus check)
(optional)
• checking synchronization 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;
• check synchronism or dead-line / dead-bus also before manual closure of the circuit
breaker possible, with separate limit values;
• measurement via transformer also possible;
• measuring voltages optionally phase-phase or phase-earth
Overvoltage
Protection
(optional)
• Overvoltage detection of each phase-earth voltage with common time delay;
• separate measuring system with a separate time delay, for the zero sequence volt-
age, or any other single-phase voltage;
• the reset ratio of the single-phase (zero sequence) voltage protection can be set;
• command transfer to the remote line end is possible.
Fault Location • Initiated by trip command or reset of the fault detection;
• computation of the distance to fault with dedicated measured value registers;
• fault location output in ohm, kilometers or miles and % of line length;
• parallel line compensation can be selected;
• load compensation available.
Circuit breaker
failure protection
(optional)
• with independent current stages for monitoring current flow through every pole of
the circuit breaker;
• with independent monitoring time steps for single-pole and three-pole tripping;
• start by trip command of every internal protection function;
• start by external trip functions possible;