Parameter OPERRAT. MODE = 1-phase
Va-n
Vb-n
Vc-n
Va-b
Vb-c
Vc-a
Vn
Vx
It is determined which voltage-measuring channel must be 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
address 213VT Connect. 3ph).
Parameter MEAS. QUANTITY = P forward or P reverse or Q forward or Q reverse
Parameter POWER
Ia Va-n
Ib Vb-n
Ic Vc-n
It is determined which power-measuring channel (current and voltage) must be evaluated
by the function. With phase-tophase voltage connections the parameter is hidden (see
address 213 VT Connect. 3ph).
When selecting Vab, Vbc, VGnd, the phase-to-ground voltages will be calculated if
“phase-to-ground“ is configured. When selecting “phase-to-phase”, the connected phase-
to-phase voltages are used and V
CA
is calculated from V
AB
and V
BC
.
NOTE
Warning!
If the 3-phase voltage connection is established at a motor or generator feeder and the Ux input is operated
at the busbar or at another voltage measuring point other than the feeder, you must select "True RMS" as
the measurement procedure. Otherwise, there is a risk of overfunction or underfunction in a situation
where the feeder voltage and the Ux voltage exhibit significantly different frequencies.
NOTE
If you have selected Vph-g, VSyn in VT Connect. 3ph, the connected phase-to-Ground voltage can be
processed. If you select VOLTAGE as measured quantity, this connected voltage is used automatically.
The forward direction of power (P forward, Q reverse) is the direction of the line. Parameter (1108 P,Q sign)
for sign inversion of the power display in the operating measured values is ignored by the flexible functions.
Via parameter PICKUP WITH it is determined whether the function must be triggered on exceeding or under-
shooting of the set threshold value.
Settings
The pickup thresholds, time delays 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 OFF-command time
delay 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, with power protection or when a function is not used as a
protection, but as a monitoring function.
When setting the power threshold values, it is important to take into consideration that a minimum current of
0.03 Ι
N
is required for power calculation. The power calculation is blocked for lower currents.
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 (see
Functions
2.18 Flexible Protection Functions
SIPROTEC 4, 7SJ80, Manual 249
E50417-G1140-C343-A8, Edition 12.2017
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