1.3 Characteristics
27
7SD5 Manual
C53000-G1176-C169-1
1.3
Characteristics
General Features
• Powerful 32-bit microprocessor system
• Complete digital processing of measured values and control, from the sampling of
the analog input values, the processing and organization of the communication
between devices up to the closing and tripping commands to the circuit breakers
• Complete galvanic and reliable separation between internal processing circuits
from the measurement, control, and power supply circuits by analog input transduc-
ers, binary inputs and outputs and the DC/DC or AC/DC converters
• Suited for lines with up to 6 ends, even with transformers in the protected zone
(order option)
• Simple device operation using the integrated operator panel or a connected person-
al computer with operator guidance
• Storage of fault indications as well as instantaneous values for fault recording
Differential
Protection
• Differential protection system for up to 6 ends with digital protection data transmis-
sion
• Protection for all types of short-circuits in systems with any starpoint conditioning
• Reliable distinction between load and short-circuit conditions, also on high resistant
faults with small fault currents;
• High sensitivity in the case of a weakly loaded system, extreme stability against
load jumps and power swings
• Due to phase segregated measurement the pickup sensitivity is independent of the
type of fault
• Suited for transformers in the protected area (order option)
• Detection of high-resistant, weak-current faults due to high sensitivity;
• Insensitive against in-rush and charge currents — also for transformers in the pro-
tected area — and against higher-frequency switching transients;
• Charging current compensation; therefore increased pickup sensitivity
• High stability also for different current transformer saturation
• Adaptive restraint that is automatically derived from the measured values and the
configured current transformer data
• Fast phase segregated tripping also on weak or zero infeed ends (breaker intertrip)
• Low dependence on frequency due to frequency tracking
• Digital transmission of protection data; communication between devices via dedi-
cated communication connections (in general optical fibre) or a communication
system
• Communication possible via ISDN networks or pilot wire connections (up to 30 km,
depends on the type of pilot wire);
• Permanent supervision of the protection data transmission concerning disturbance,
failure, and transfer time deviation in the transmission network, with automatic
transfer time correction
• Automatic changeover of communication paths in case of transmission failure or
transmission disturbance is provided (for ring topology with 7SD5*3)
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