3$
)NSTALLATION INSTRUCTIONS
6
# ' #
#ONNECTIONS
'ENERAL AND CONNECTION DIAGRAMS ARE SHOWN IN !P
PENDIX ! AND " 4HE THREE INPUT WINDINGS OF THE SUM
MATION TRANSFORMER PERMIT VARIOUS CONNECTION POS
SIBILITIES TO THE CURRENT TRANSFORMERS THE MOST COM
MON ARE DESCRIBED IN THE FOLLOWING SUBSECTIONS )T IS
IMPERATIVE THAT THE CONNECTION MODE IS THE SAME AT
THE TWO OR THREE WITH TEED LINES LINE ENDS 4HE MAR
SHALLING POSSIBILITIES OF THE BINARY INPUTS AND OUTPUTS
ARE DESCRIBED IN 3ECTION
3TANDARD CONNECTION , , %
4HE STANDARD CONNECTION IS SUITED TO ALL TYPES OF NET
WORK REGARDLESS OF THE TREATMENT OF THE SYSTEM NEU
TRAL &IGURE ILLUSTRATES THE MEASURED CURRENT CON
NECTIONS 4HE SENSITIVITY FOR PHASETOPHASE FAULTS
LIES BETWEEN AND TIMES THE SENSITIVITY FOR
SYMMETRICAL CURRENTS &OR EARTH CURRENTS THE SENSI
TIVITY IS HIGHER BY THE FACTOR TO )N ISOLATED OR
ARC COMPENSATED SYSTEMS THE RELAY CAN BE
ADAPTED TO THE DOUBLE EARTH FAULT PREFERENCE OF THE
SYSTEM BY CYCLIC OR ACYCLIC CHANGE OF THE PHASES
4HE PREFERRED PHASE IS THEN CONNECTED TO THE FIRST
SUMMATION TRANSFORMER WINDING WITH THE WEIGHTING
FACTOR THE PHASE WITH THE LEAST PREFERENCE IS NOT
DIRECTLY CONNECTED TO THE RELAY 4HUS THE CONNECTION
DIAGRAM ACCORDING TO &IGURE CORRESPONDS TO A
DOUBLE EARTH FAULT PREFERENCE , BEFORE , BEFORE ,
4HE SAME CONNECTION METHOD SHOULD BE USED
THROUGHOUT A GALVANICALLY INTERCONNECTED SYSTEM
AND MUST BE USED AT THE LINE ENDS OF A DIFFERENTIAL
PROTECTION SCHEME
-4
, , ,
3$
&
&
&
&
%
%
&IGURE
3TANDARD CONNECTION , , %
#ONNECTION FOR DECREASED EARTH CUR
RENT SENSITIVITY , , ,
)N EARTHED SYSTEMS WITH PARTICULARLY LOW ZERO SE
QUENCE IMPEDANCE EARTH FAULT CURRENTS CAN BE LARG
ER THAN THOSE UNDER TWOPHASE FAULT CONDITIONS 7ITH
CONSIDERATION OF THE THERMAL LOADING ON THE MEASUR
ING CIRCUITS THE CONNECTIONS SHOWN IN &IGURE IS
USED 7ITH THIS CONNECTION SENSITIVITY FOR ALL TYPES OF
FAULTS LIES BETWEEN AND TIMES THE SENSITIV
ITY UNDER SYMMETRICAL THREEPHASE CURRENT CONDI
TIONS
-4
, , ,
3$
&
&
&
&
%
%
&IGURE
#ONNECTION , , , WITH DE
CREASED EARTH CURRENT SENSITIVITY
#ONNECTION FOR INCREASED EARTH CURRENT
SENSITIVITY
)N CERTAIN SYSTEMS EARTH FAULT CURRENTS OF EVEN LOWER
VALUES MUST BE DETECTED AND CLEARED AS IT IS POSSI
BLE WITH THE STANDARD CONNECTION EG BECAUSE OF AN
EARTHING RESISTANCE RESISTANCE EARTHED SYSTEMS
4O A CERTAIN EXTENT THIS CAN BE ACHIEVED BY USING AN
INTERMEDIATE AUTOTRANSFORMER )4 AS SHOWN IN &IGURE
$EPENDENT OF THE BURDEN ON THE CURRENT TRANS
FORMERS THE CURRENT IN THE STAR POINT CONDUCTOR CAN
BE INCREASED TO APPROXIMATELY DOUBLE THE NORMAL
VALUE %ARTH FAULT SENSITIVITY WILL THEN BE INCREASED TO
TO TIMES THE SENSITIVITY UNDER SYMMETRICAL
THREEPHASE CURRENT CONDITIONS 0HASE FAULT SENSITIV
ITY IS THE SAME AS WITH THE STANDARD CONNECTION
Summary of Contents for 7SD502
Page 148: ... PPENDIX 3 6 PPENDIX ENERAL DIAGRAMS ONNECTION DIAGRAMS 4ABLES ...
Page 176: ... 3 6 ...