1.3 Characteristics
25
7UM61 Manual
C53000-G1176-C127-3
Rate-of-Frequency-
Change Protection
• Monitors whether the frequency overshoots (df/dt>) and/or undershoots (df/dt<) a
set limit value, with 4 individually settable limit values or delay times.
• Variable measuring windows
• Coupling to frequency protection pickup.
• Settable undervoltage threshold.
Vector Jump • Sensitive phase jump detection to be used for network disconnection.
90% Stator Earth
Fault Protection
• Suitable for generators in unit connection and directly connected to busbars.
• Measurement of displacement voltage via the neutral or earthing transformer or by
calculation from phase-to-earth voltages.
• Highly sensitive earth current detection, optional with or without directional determi-
nation with zero sequence components (I
0
, U
0
).
• Directional characteristic adjustable.
• Determination of the earth-faulted phase.
Sensitive Earth
F a u l t P r o t e c t i o n
• Two-stage earth fault current measurement: I
EE
>> and I
EE
>.
• High sensitivity (adjustable on the secondary side from 2 mA).
• Can be used for stator earth fault or rotor earth fault detection.
• Measurement circuit monitoring for minimum current flow when used for rotor earth
fault protection.
100% Stator Earth
Fault Protection
w i t h 3 r d H a r m o n i c
• Detection of the 3rd harmonic of the voltage at the starpoint or broken delta winding
of an earthing transformer.
• In addition to the 90-%-stator earth fault protection there is a protection of the entire
stator winding (protective range 100 %).
Motor Starting Time
Supervision
• Inverse time overcurrent tripping based on an evaluation of the motor starting
current
• Inverse time delay with blocked rotor.
Restart Inhibit for
Motors
• Approximate computation of rotor overtemperature.
• Motor switchon is enabled only a if a restartup limit is undershot.
• Calculation of waiting time until automatic reclosure is enabled.
• Different prolongation of cooldown time constants for standstill/operation period is
taken into consideration.
• Possibility for disabling the start inhibit if emergency startup is required.
Breaker Failure
Protection
• By checking the current or evaluation of the breaker auxiliary contacts.
• Initiation of each integrated protection function allocated to the circuit breaker.
• Initiation possible through a binary input from an external protective device.
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