-ETHOD OF OPERATION3*
6
#
' #
"LOCK )P DIRECTIONAL
31
2
"LOCK /# 0H DIRECTIONAL
)
,
DIR &AULT ,
)P "LOCK DIR
DIR /# 0 BLK
DIR /# OFF
DIR /# 0H ON
31
2
DIR /# 0 OFF
)P DIR 4RIP
,
,
,
)P DIR&AULT
DIRECTIONAL DE
TERMINATION
)
,
5
, ,
&.O
&.R
&.O
&.O
&.O
&.O
!NNUNCIATION
4RIPPING
4HE PROCESSING OF THE INVERSE TIME CHARAC
TERISTIC IS TO BE REPLACED BY THE DEFINITE TIMER
IN DEFINITE TIME MODE
$IRECTIONAL /# 0H OFF
$IRECTIONAL /# 0H ON
RESET MEASUREMENT
&UNCTION NUMBER
-!.#,/3%
).%&&%#4)6%
))P DIR 5.$%,!9%$
-ANUAL CLOSE
&IGURE ,OGIC DIAGRAM OF THE DIRECTIONAL OVERCURRENT TIME PROTECTION EXAMPLE WITH INVERSE TIME MODE
2EVERSE INTERLOCKING ON DOUBLE END FED LINES
4HE PRINCIPLE OF REVERSE INTERLOCKING CAN ALSO BE
USED ON LINES WITH INFEED FROM BOTH SIDES OR IN RING
NETWORKS 4HIS RESULTS IN FAST TRIPPING OF FAULTS AT ANY
LOCATION WITHOUT THE NEED TO WAIT FOR DELAY ACCORDING
TO THE TIME GRADING PLAN AS EG IN &IGURE 4HE
DISTANCES BETWEEN THE SUBSTATIONS SHOULD BE NOT
TOO LONG SO THAT THE INTERLOCKING SIGNAL CAN BE TRANS
MITTED VIA A DC LINK ! PAIR OF WIRES MUST BE AVAILABLE
FOR EACH DIRECTION
4HE PRINCIPLE IS SHOWN IN &IGURE 4HE NON
DI
RECTIONAL STAGES ) ARE SET TO A SLIGHT DELAY EG
MS A WAITING MARGIN FOR SAFE DETECTION OF THE IN
TERLOCK SIGNAL )T IS ESSENTIAL THAT THE COMPLETE CHAIN
OF LINE AND BUSBAR SECTIONS IS INCLUDED IN THE INTER
LOCKING SCHEME ! RELAY THAT DETECTS A FAULT IN RE
VERSE DIRECTION BLOCKS THE NON
DIRECTIONAL STAGE OF
THE RELAY AT THE OPPOSITE LINE END ! RELAY WHICH DE
TECTS A FAULT IN FORWARD DIRECTION BLOCKS THE NON
DI
RECTIONAL STAGE OF THE RELAY IN REVERSE DIRECTION IE
ON THE NEXT LINE AT THE SAME BUSBAR 4HE DIRECTIONAL
STAGES OF ALL RELAYS REMAIN AS BACKUP PROTECTION WITH
NORMAL TIME GRADING
3* GENERATES THE NECESSARY SIGNALS FOR THIS PUR
POSE AS SHOWN IN &IGURE 7HEN THE TRANSMIS
SION LINK IS DISTURBED THE RELAY CAN BE INFORMED VIA
BINARY INPUTS 4HE DISTURBANCE IS THEN ANNUNCIATED
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