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Functions
2.6 Flexible Protection Functions
NOTE
i
i
With regard to the phase-selective pickup messages, a special behavior is observed in the three-phase
voltage protection with phase-to-phase variables, because the phase-selective pickup message "Flx01
Pickup Lx" is allocated to the respective measured-value channel "Lx".
Single-phase faults:
If, for example, voltage V
device indicates pickups "Flx01 Pickup A" and "Flx01 Pickup C", because the undershooting was detected in
the first and third measured-value channel.
Two-phase faults:
If, for example, voltage V
cates pickup "Flx01 Pickup A", because the undershooting was detected in the first measured-value
channel.
Table 2-9
Parameter OPERRAT. MODE = 1-phase
Parameter MEAS. QUANTITY = Voltage
Parameter
MEAS. METHOD
Fundamental
True RMS
Parameter MEAS. QUANTITY = Voltage
Parameter VOLTAGE
Va-n
Vb-n
Vc-n
Va-b
Vb-c
Vc-a
Vn
Vx
Settings
The pickup thresholds, delay times and dropout ratios of the flexible protection function are set in the
"Settings" dialog box in DIGSI.
The pickup threshold of the function is configured via parameter P.U. THRESHOLD. The TRIP-command delay
time is set via parameter T TRIP DELAY. Both setting values must be selected according to the required
application.
The pickup can be delayed via parameter T PICKUP DELAY. This parameter is usually set to zero (default
setting) in protection applications, because a protection function should pick up as quickly as possible. A
setting deviating from zero may be appropriate if a trip log is not desired to be started upon each short-term
exceeding of the pickup threshold, for example, when a function is not used as a protection, but as a moni-
toring function.
The dropout of pickup can be delayed via parameter T DROPOUT DELAY. This setting is also set to zero by
default (standard setting) A setting deviating from zero may be required if the device is utilized together with
electro-magnetic devices with considerably longer dropout ratios than the digital protection device. When
utilizing the dropout time delay, it is recommended to set it to a shorter time than the OFF-command delay
time in order to avoid both times to "race".
76
drops to such degree that voltages V
A
drops to such degree that its threshold value is reached, the device then indi-
AB
Parameter in the Setting Dialog "Measurement Procedure", Mode of Operation 1-phase
Only the fundamental harmonic is evaluated, higher harmonics are suppressed. This is
the standard measurement procedure of the protection functions.
The "True" RMS value is determined, i.e. higher harmonics are evaluated.
It is determined which voltage-measuring channel is evaluated by the function. When
selecting phase-to-phase voltage, the threshold value must be set as a phase-to-phase
value, when selecting a phase-to-ground variable as phase-toground voltage. The extent
of the setting texts depends on the connection of the voltage transformer (see
address213 VT Connect. 3ph).
and V
exceed their threshold values, the
AB
A
SIPROTEC 4, 7RW80, Manual
C53000-G1140-C233-4, Edition 07.2018
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