Siemens SIPROTEC 7SJ531 - Page 79

-ETHOD OF OPERATION3*
6

#
' #
 !UTOMATIC RECLOSURE OPTIONAL
 'ENERAL
%XPERIENCE HAS SHOWN THAT APPROXIMATELY   OF
SHORT CIRCUITS ARE CAUSED BY AN ARC ON OVERHEAD
LINES AND SELF
EXTINGUISH AFTER INTERRUPTION BY THE
PROTECTIVE DEVICE 4HE LINE CAN THEREFORE BE RE
EN
ERGIZED 4HIS IS CARRIED OUT BY THE AUTOMATIC RECLO
SURE !2 FUNCTION )N CASE OF GENERATORS MOTORS
TRANSFORMERS REACTORS OR CABLES AUTO
RECLOSURE IS
NOT REASONABLE AND THIS FUNCTION MUST BE DE
CONFI
GURED
)F THE SHORT
CIRCUIT IS STILL PRESENT AFTER THE AUTO RE
CLOSURE ARC NOT QUENCHED OR METALLIC SHORT CIRCUIT
THEN THE PROTECTIVE RELAY FINALLY DISCONNECTS THE POW
ER -ULTIPLE AUTO
RECLOSURE ATTEMPTS OFTEN WITH A
FIRST RAPID AUTO
RECLOSURE 2!2 AND SUBSEQUENT
DELAYED AUTO
RECLOSE CYCLES $!2 ARE POSSIBLE IN
SOME NETWORKS
3* ALLOWS AUTOMATIC THREE
POLE AS WELL AS
SINGLE
AND MULTI SHOT RECLOSURE )F MORE THAN ONE
RECLOSE ATTEMPT WILL BE CARRIED OUT THE SECOND AND
ANY FURTHER AUTO
RECLOSE CYCLE ARE DESIGNATED IN THE
FOLLOWING WITH $!2 DELAYED AUTO
RECLOSURE INDE
PENDENT ON THE SETTING OF THE DEAD TIMES OF THE
CYCLES
4HE POSSIBILITIES AND FUNCTIONS OF THE INTERNAL !2
UNIT ARE DESCRIBED IN THE FOLLOWING SECTIONS 0REREQ
UISITE FOR INITIATION OF THE !2
FUNCTION IS THAT THE CIR
CUIT BREAKER IS READY FOR OPERATION WHEN PICK
UP OC
CURS 4HIS INFORMATION HAS TO BE TRANSMITTED TO THE
DEVICE VIA A BINARY INPUT
&URTHERMORE RECLOSURE IS BLOCKED IF THE TRIPPING
COMMAND OCCURS AFTER THE ACTION TIME WHICH CAN BE
SET INDIVIDUALLY FOR 2!2 AND $!2
 0ROTECTION STAGES AND SELECTIV
ITY DURING AUTOMATIC RECLOSURE
&OR THE AUTO RECLOSURE SEQUENCE TO BE SUCCESSFUL
FAULTS ON ANY PART OF THE LINE MUST BE CLEARED FROM THE
FEEDING LINE ENDS WITHIN THE SAME
SHORTEST POSSI
BLE
TIME 5SUALLY THEREFORE AN INSTANTANEOUS
STAGE OF THE SHORT
CIRCUIT PROTECTION IS SET TO OPERATE
BEFORE A RECLOSURE BY THE !2
UNIT &URTHERMORE
ONE CAN DECIDE FOR EACH SHORT
CIRCUIT PROTECTION
STAGE WHETHER OR NOT IT SHALL GENERALLY INITIATE THE AU
TO
RECLOSE FUNCTION
&OR EACH OF THE PROTECTION STAGES
) STAGE FOR PHASE CURRENTS
) STAGE DEFINITE TIME OR )
P
STAGE INVERSE TIME
FOR PHASE CURRENTS
)
%
 STAGE FOR EARTH CURRENT
)
%
 STAGE DEFINITE TIME OR )
%P
STAGE INVERSE
TIME FOR EARTH CURRENT
) $)2 STAGE FOR PHASE CURRENTS
) $)2 STAGE DEFINITE TIME OR )
P
$)2 INVERSE TIME
FOR PHASE CURRENTS
)
%
 $)2 FOR EARTH CURRENT
)
%
 $)2 STAGE DEFINITE TIME OR )
%P
STAGE INVERSE
TIME FOR EARTH CURRENT
) STAGE OF UNBALANCED LOAD PROTECTION
) STAGE OF UNBALANCED LOAD PROTECTION
CAN BE INDIVIDUALLY CHOSEN WHETHER THE STAGE SHALL
INITIATE 2!2 FUNCTION OR NOT
4HE REMAINING PROTECTION FUNCTIONS
CIRCUIT BREAK
ER FAILURE PROTECTION USER DEFINED TRIP FUNCTION
AL
WAYS OPERATE WITHOUT AUTO
RECLOSURE THEREFORE
THEY HAVE NO !2 STAGES !UTO
RECLOSE IS ALWAYS
BLOCKED WHEN THE CIRCUIT BREAKER FAILURE PROTECTION
HAS TRIPPED
4HE AUTO
RECLOSE FUNCTION PROVIDES AN ACTION TIME
FOR EACH OF 2!2 AND $!2 FUNCTION WHICH CAN BE SEP
ARATELY SET 4HE ACTION TIMES ARE STARTED WITH ANY
FAULT DETECTION OF A PROTECTION STAGE WHICH SHALL TRIG
GER THE !2 FUNCTION )F THE ACTION TIME HAS ELAPSED
BEFORE ANY TRIP SIGNAL IS GIVEN IT IS ASSUMED THAT THE
FAULT IS NOT ON THE PROTECTED LINE BUT ON ANOTHER LINE
AUTO
RECLOSURE IS NOT INITIATED
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