Table of Contents
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Introduction
1.3 Characteristics
Thermal Overload Protection 49
• Temperature image of current heat losses (overload protection with full memory capability, single body
thermal model).
• Additional adjustable warning levels based on temperature rise and current magnitude.
• Consideration of coolant and ambient temperatures possible.
Negative Sequence Protection 46-1, 46-2, 46-TOC
• Precise evaluation of negative sequence component of the three phase currents.
• Alarm stage when a set unbalanced load is exceeded.
• Thermal characteristic with adjustable negative sequence factor and adjustable cooldown time.
• High-speed trip stage for large unbalanced loads (can be used for short-circuit protection).
Startup Overcurrent Protection
• I> stage for lower speed ranges (e.g. startup of generators with startup converter).
Differential Protection
• Use for generator, motor or transformer differential protection
• Tripping characteristic with restraining current;
• High sensitivity.
• Insensitivity to DC components and current transformer saturation;
• High degree of stability even with different degrees of CT saturation.
• Restraint feature against high inrush currents with 2nd harmonic;
• Restraint feature against transient and steady-state fault currents with 3rd or 5th harmonics;
• High-speed tripping in case of high-current faults;
• Integrated matching of transformer vector group.
• Integrated matching of transformation ratio with consideration of different c.t. rated currents.
Ground Current Differential Protection
• Tripping characteristic with restraining current;
• Variable selection of measured quantities for all normal system conditions.
• High sensitivity.
• Additional stabilisation measures against overfunction with external faults.
Underexcitation Protection
• Conductance measurement from positive sequence components.
• Multi-step characteristic for steady-state and dynamic stability limits.
• Consideration of the excitation voltage.
28
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
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