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Introduction
1.3 Characteristics
Time Overcurrent Protection
•
Optionally selectable as emergency function during protection data communication failure or as backup
function or both
•
A maximum of 3 definite time elements and one inverse time element, each for phase currents and
ground current
•
A maximum of 2 directional definite time elements and one directional inverse time element, each for
phase currents and ground current
•
For inverse time overcurrent protection, selection from various characteristics of different standards
possible
•
Blocking options e.g. for reverse interlocking with any element
•
Instantaneous tripping when closing onto a short circuit possible with any element
Inrush Current Restraint
•
Insensitive to inrush currents and against higher-frequency transients
•
High stability also for different current transformer saturation
Circuit-Breaker Failure Protection
•
With independent current elements for the monitoring of the current flow through each pole of the
circuit breaker
•
Separate pickup thresholds for phase and ground currents
•
Monitoring time element for tripping
•
Initiation by the trip command of each integrated protection function
•
Initiation by external trip functions possible
•
Single-element or two-element
•
No dropout and seal-in times
Thermal Overload Protection
•
Thermal replica of the current heat losses of the protected object
•
RMS measurement for all three phase currents
•
Adjustable thermal and current-dependent warning elements
Voltage Protection
•
Overvoltage and undervoltage detection with different elements
•
2 overvoltage elements for the phase-to-ground voltages
•
2 overvoltage elements for the phase-to-phase voltages
•
2 overvoltage elements for the positive sequence voltage
•
2 overvoltage elements for the negative sequence system of the voltages
•
2 overvoltage elements for the zero system of the voltages or for any other single-phase voltage
•
Adjustable dropout conditions
•
2 undervoltage elements for the phase-to-ground voltages
•
2 undervoltage elements for the phase-to-phase voltages
•
2 undervoltage elements for the positive sequence system of the voltages
•
Adjustable current criterion for undervoltage protection functions
26
SIPROTEC 4, 7SD80, Manual
E50417-G1100-C474-A2, Edition 02.2018
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