/PERATING INSTRUCTIONS
3$
6
# ' #
4ESTING THE THERMAL OVERLOAD PROTECTION FUNCTION
4HE INTEGRATED OVERLOAD PROTECTION CAN ONLY BE
TESTED IF IT HAS BEEN CONFIGURED AS 4(%2-!, /,
%8)34
ADDRESS REFER 3ECTION AND PARA
METERIZED AS OPERATIVE IE IT MUST BE SET UNDER AD
DRESS 4(%2-!, /,
/.
OR
",/#+ 42)0
2%,
)N THE LATTER CASE THE PROTECTION WILL OPERATE BUT
NO TRIP COMMAND IS GIVEN TO ANY TRIP RELAY
4HE BASIS CURRENT FOR THE DETECTION OF OVERLOAD IS THE
RATED CURRENT OF THE LINE AS PARAMETERIZED UNDER AD
DRESS /VERLOAD IS A THREEPHASE SYMMETRICAL
OCCURRENCE THUS THE BASIS CURRENT IS RELATED TO
THREEPHASE CURRENT CONDITIONS WITH STANDARD CON
NECTION OF THE SUMMATION TRANSFORMER ACCORDING TO
&IGURE
7HEN TESTS ARE PERFORMED WITH THE STANDARD CON
NECTIONS OR CONNECTIONS WHICH FORM THE SAME
WEIGHTING FACTOR NO FURTHER CONDITIONS ARE TO BE CON
SIDERED $URING SINGLEPHASE TEST IT MUST BE CONSID
ERED THAT THE CURRENT WHICH IS EVALUATED BY THE RELAY
DEPENDS ON THE CONNECTION MODE OF THE SUMMATION
TRANSFORMER BESIDES ON THE RATED LINE CURRENT
)
0
)
-
|
.
-4
|
.
PAR
WHERE
)
0
TEST CURRENT
)
-
MIXED CURRENT AS IT IS EVALUATED BY THE
RELAY
.
-4
FACTOR CAUSED BY THE MODE OF CONNECTION
OF THE SUMMATION MIXING TRANSFORMER
.
PAR
FACTOR CAUSED BY PARAMETER SETTING
4HE FACTORS .
-4
AND .
PAR
ARE THE SAME AS DEFINED
AND EXPLAINED FOR TESTING OF THE DIFFERENTIAL PROTECTION
REFER TO 3ECTION 4ABLE AND THE ASSOCIATED
FORMULAE
7HEN APPLYING A TEST CURRENT OF
)
0
)
. DEVICE
|
.
-4
|
.
PAR
|
K
TRIPPING MUST NOT OCCUR !FTER AN APPROPRIATE TIME
APPROXIMATELY X
Ç
A STEADYSTATE TEMPERATURE RISE
ACCORDING TO THE FOLLOWING RELATIONSHIP IS ESTAB
LISHED
K
TRIP
4HIS VALUE CAN BE READ OUT IN ADDRESS BLOCK
4O CHECK THE TIME CONSTANT THE CURRENT INPUT IS SIM
PLY SUBJECTED TO X THE PICKUP VALUE I E
|
)
.
DEVICE
|
.
-4
|
.
PAR
|
K
4RIPPING WILL THEN BE INITIATED AF
TER A TIME INTERVAL WHICH CORRESPONDS TO HALF THE TIME
CONSTANT
)T IS ALSO POSSIBLE TO CHECK THE TRIP CHARACTERISTIC &IG
URE )T MUST BE NOTED THAT BEFORE EACH MEASURE
MENT THE TEMPERATURE RISE MUST BE REDUCED TO ZERO
4HIS CAN BE ACHIEVED BY EITHER DEACTIVATING AND RE
ACTIVATING THE OVERLOAD FUNCTION ADDRESS OR
BY OBSERVING A CURRENT FREE PERIOD OF AT LEAST X
Ç
4EST CURRENTS LARGER THAN TIMES )
.
MAY
OVERLOAD AND DAMAGE THE RELAY IF APPLIED
CONTINUOUSLY REFER TO 3ECTION FOR
OVERLOAD CAPABILITY /BSERVE A COOLING
DOWN PERIOD
#AUTION
)F TESTING WITH PRELOAD IS PERFORMED THEN IT MUST BE
ENSURED THAT A CONDITION OF THERMAL EQUILIBRIUM HAS
BEEN ESTABLISHED BEFORE TIME MEASUREMENT COM
MENCES 4HIS IS THE CASE WHEN THE PRELOAD HAS
BEEN APPLIED CONSTANTLY FOR A PERIOD OF AT LEAST X
Ç
Содержание 7SD502
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