)NTRODUCTION
3$
6
# ' #
)MPLEMENTED FUNCTIONS
4HE NUMERICAL LINE DIFFERENTIAL PROTECTION RELAY
3$ CONTAINS THE FOLLOWING FUNCTIONS
$IFFERENTIAL PROTECTION
PROTECTION FOR ALL KINDS OF SHORTCIRCUITS IN SYSTEMS
WITH EARTHED OR NONEARTHED STARPOINT
CURRENT RESTRAINT COMPENSATES FOR CT TRANSFORMA
TION ERRORS UNDER THROUGHFAULT CONDITIONS
ADDITIONAL DYNAMIC STABILIZATION AGAINST DIFFERENT
CURRENT TRANSFORMER SATURATION
SECOND HARMONIC STABILIZATION FOR INCLUSION OF A
POWER TRANSFORMER IN THE PROTECTED ZONE
ONE END TRIPPING FOR FAULT FED FROM ONE END ONLY
OPTIONALLY TRIPPING OF THE NONFEEDING END POS
SIBLE
DATA EXCHANGE WITH OPPOSITE STATION VIA A PAIR OF
SYMMETRICAL PILOT WIRES
PILOT WIRE RESISTANCE IS ADJUSTED BY INTERNAL CALCU
LATION
COMPENSATION OF THE PILOT WIRE CAPACITANCE BY IN
TERNAL CALCULATION WITHOUT EXTERNAL COMPONENTS
OPTIONAL CONTINUOUS PILOT WIRE SUPERVISION WITH
PULSE CODED VOICE FREQUENCY SIGNAL
/VERCURRENT TIME PROTECTION
OPERATES AS DEFINITE TIME OR INVERSE TIME OVERCUR
RENT PROTECTION WITH SELECTABLE CHARACTERISTICS
SEPARATE HIGH CURRENT STAGE WITH DEFINITE TIME
CHARACTERISTIC OR INSTANTANEOUS TRIP
$IRECT LOCAL AND TRANSFER TRIP
TRIPPING OF THE LOCAL CIRCUIT BREAKER FROM AN EXTER
NAL SOURCE WITH ADJUSTABLE DELAY AND RESET TIME
TRIPPING OF THE REMOTE END CIRCUIT BREAKER BY AN
EXTERNAL SIGNAL EG BREAKER FAILURE PROTECTION
MODELS WITH PILOT WIRE MONITOR
4HERMAL OVERLOAD PROTECTION
PROVIDES THERMAL REPLICA OF THE CURRENT HEAT
LOSSES
TRUE RMS MEASUREMENT OF SYMMETRICAL CURRENTS
ADJUSTABLE WARNING STAGES
4HE STANDARD FUNCTIONS ALSO INCLUDE
CONTINUOUS SELFMONITORING RIGHT FROM THE $# CIR
CUITS THROUGH THE CURRENT INPUTS TO THE TRIPPING RE
LAYS THUS ACHIEVING MAXIMUM AVAILABILITY AND A
MORE CORRECTIVE THAN PREVENTIVE MAINTENANCE
STRATEGY
MEASUREMENT AND TEST ROUTINES UNDER NORMAL
LOAD CONDITIONS MEASUREMENT OF LOAD CURRENT
ANNUNCIATION STORAGE FOR THE LAST THREE NETWORK
FAULTS WITH REAL TIME CLOCK
DATA STORAGE AND TRANSMISSION FOR FAULT RECORDS
GIVING
RAPID FAULT ANALYSIS
DETAILED FAULT RECORDS
COUNTING OF TRIPPING COMMANDS AS WELL AS RECORD
ING OF FAULT DATA AND ACCUMULATIVE ADDITION OF THE
INTERRUPTED FAULT CURRENTS
COMMISSIONING AIDS SUCH AS CONNECTION CHECK
MEASUREMENT OF THE PILOT WIRE RESISTANCE AND CA
PACITANCE AND CIRCUIT BREAKER LIVE TEST
/PERATION WITH OTHER DIFFERENTIAL RELAYS
4HE NUMERICAL LINE DIFFERENTIAL PROTECTION RELAY
3$ IS NOT SUITABLE FOR USE WITH OTHER TYPES OF DIF
FERENTIAL RELAYS 4HE INTERNAL ADJUSTMENT OF THE INFLU
ENCE OF THE PILOT WIRE RESISTANCE AND THE OPTIONAL
PILOT WIRE SUPERVISION USING A PULSE CODE MODULATED
VOICE FREQUENCY CANNOT OPERATE WITH DIFFERENT TYPES
OF DIFFERENTIAL RELAYS WITH TWO PILOT WIRES 3HOULD IT BE
COME NECESSARY TO DIVIDE A LINE WHICH IS PROTECTED
BY ELECTROMECHANICAL OR ANALOGSTATICAL RELAYS INTO
TWO SECTIONS IT IS ADVISABLE TO INSTALL 3$ AT BOTH
ENDS OF ONE OF THE LINE SECTIONS AND TO USE THE EXIST
ING RELAY PAIR FOR THE OTHER LINE SECTION OF COURSE
BOTH SECTIONS CAN BE PROTECTED WITH 3$ PROTEC
TION SYSTEMS
Summary of Contents for 7SD502
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