Siemens SIPROTEC 7UT613 series Manual page 25

Time Overcurrent
Protection for Earth
Current
1-phase Overcur-
rent Protection
Unbalanced Load
Protection
7UT613/63x Manual
C53000-G1176-C160-2
• Instantaneous tripping possible at any stage when closing onto a short-circuit
• Inrush restraint using the second harmonic of the measured current
• Dynamic switchover of the time overcurrent protection settings, e.g. during cold-
load start-up of the power plant
• 3 time overcurrent protection functions for phase currents and residual current
• Two definite time delayed overcurrent stages for the earth current, e.g. current
between starpoint and earth
• Additionally, one inverse time delayed overcurrent stage for the earth current
• Selection of various inverse time characteristics of different standards is possible,
alternatively a user defined characteristic can be specified
• The three can be combined as desired
• External blocking facility for any desired stage (e.g. for reverse interlocking)
• Instantaneous trip when switching on a dead fault with any desired stage
• Inrush restraint function with 2nd harmonic
• Dynamic switchover of the time overcurrent parameters, e.g. during cold-loaded
start-up of the power plant
• 2 time overcurrent protection functions are possible for earth current
• Two definite time delayed overcurrent stages which can be combined as desired
• For any 1-phase overcurrent detection
• Can be assigned to the „normal "1-phase current input or to the highly sensitive
current input
• Suitable for detection of very small current (e.g. for high-impedance unit protection
or tank leakage protection)
• Suitable for detection of any desired AC voltage using an external series resistor
(e.g. for high-impedance unit protection)
• External blocking facility for any stage
• Evaluation of the negative sequence system of the three phase currents of any
desired side of the protected object or any three-phase measuring point
• Two definite time delayed negative sequence current stages and one additional
inverse time delayed negative sequence current stage
• Selection of various inverse time characteristics of different standards is possible,
alternatively a user defined characteristic can be specified
• The stages can be combined as desired.
• Trip blocking on detection of broken wire
• Thermal characteristic with adjustable negative sequence factor and adjustable
cooldown time.
1.3 Characteristics
25