Siemens SIPROTEC 7SJ531 - Page 50

-ETHOD OF OPERATION3*
6
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' #
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4HE ANALOG INPUT SECTION !% CONTAINS INPUT AMPLIFI
ERS SAMPLE AND HOLD ELEMENTS FOR EACH INPUT ANA
LOG
TO DIGITAL CONVERTERS AND MEMORY CIRCUITS FOR
THE DATA TRANSFER TO THE MICROPROCESSOR
!PART FROM CONTROL AND SUPERVISION OF THE MEASURED
VALUES THE MICROPROCESSOR PROCESSES THE ACTUAL
PROTECTIVE AND MEASUREMENT FUNCTIONS 4HESE IN
CLUDE IN PARTICULAR
FILTERING AND FORMATION OF THE MEASURED QUANTITIES
CONTINUOUS CALCULATION OF THE VALUES WHICH ARE
RELEVANT FOR FAULT DETECTION CONTROL AND SUPERVI
SION
DETERMINATION OF THE FAULT DIRECTION MODELS WITH
DIRECTION DETERMINATION
CALCULATION OF THE NEGATIVE SEQUENCE CURRENT FOR
UNBALANCED LOAD DETECTION
CALCULATION OF THE TRUE RMS VALUES FOR THE THERMAL
REPLICA OF THE OVERLOAD PROTECTION
CALCULATION OF THE EARTH FAULT DATA
SCANNING OF LIMIT VALUES AND TIME SEQUENCES
DECISION ABOUT TRIP AND CLOSE COMMANDS
CALCULATION OF THE ACTIVE AND REACTIVE COMPONENTS
OF THE POWER
METERING OF ACTIVE AND REACTIVE ENERGY
DETERMINATION OF THE SYSTEM FREQUENCY
STORAGE OF MEASURED QUANTITIES DURING A FAULT FOR
ANALYSIS
"INARY INPUTS AND OUTPUTS TO AND FROM THE PROCESSOR
ARE CHANNELLED VIA THE INPUTOUTPUT ELEMENTS &ROM
THESE THE PROCESSOR RECEIVES INFORMATION FROM THE
SWITCH
GEAR EG POSITION OF THE CIRCUIT BREAKER OR
FROM OTHER EQUIPMENT EG BLOCKING SIGNALS /UT
PUTS INCLUDE IN PARTICULAR TRIP AND CLOSE COMMANDS
TO THE CIRCUIT BREAKER SIGNALS FOR REMOTE SIGNALLING OF
IMPORTANT EVENTS AND CONDITIONS AS WELL AS VISUAL IN
DICATORS ,%$S AND A GRAPHIC DISPLAY ON THE FRONT
!N INTEGRATED MEMBRANE KEYBOARD IN CONNECTION
WITH A BUILT
IN GRAPHIC ,#$ DISPLAY ENABLES COM
MUNICATION WITH THE UNIT !LL OPERATIONAL DATA SUCH AS
SETTING VALUES PLANT DATA ETC ARE ENTERED INTO THE
PROTECTION FROM THIS PANEL REFER TO 3ECTION  5S
ING THIS PANEL THE PARAMETERS CAN BE RECALLED AND
THE RELEVANT DATA FOR THE EVALUATION OF A FAULT CAN BE
READ OUT AFTER A FAULT HAS OCCURRED REFER TO 3ECTION
 4HE DIALOG WITH THE RELAY CAN BE CARRIED OUT AL
TERNATIVELY VIA THE SERIAL OPERATING INTERFACE ON THE
FRONT PLATE BY MEANS OF A PERSONAL COMPUTER
6IA A SECOND SERIAL INTERFACE OPTIONAL FAULT DATA
CAN BE TRANSMITTED TO A CENTRAL EVALUATION UNIT $UR
ING HEALTHY OPERATION MEASURED VALUES CAN ALSO BE
TRANSMITTED EG THE MEASURED CURRENTS AND VOLT
AGES AT THE POINT OF INSTALLATION 4HIS SECOND INTER
FACE IS SUITABLE FOR CONNECTION OF OPTICAL FIBRE LINKS
! POWER SUPPLY UNIT PROVIDES THE AUXILIARY SUPPLY ON
THE VARIOUS VOLTAGE LEVELS TO THE DESCRIBED FUNCTIONAL
UNITS  6 IS USED FOR THE RELAY OUTPUTS 4HE ANALOG
INPUT REQUIRES q 6 WHEREAS THE PROCESSOR AND ITS
IMMEDIATE PERIPHERALS ARE SUPPLIED WITH  6 4RAN
SIENT FAILURES IN THE SUPPLY VOLTAGE UP TO  MS
WHICH MAY OCCUR DURING SHORT
CIRCUITS IN THE DC
SUPPLY SYSTEM OF THE PLANT ARE BRIDGED BY A DC VOLT
AGE STORAGE ELEMENT RATED AUXILIARY VOLTAGE 
 6
DC
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