-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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