Siemens SIPROTEC 4 7UT6 Series Manual page 157

The corresponding time multiplier is accessible via address 2223 T 3I0p. This has to be coordinated with the
grading coordination chart of the network. For earth currents with earthed network, you can mostly set up a
separate grading coordination chart with shorter delay times. If you set a very small pickup value, consider
that the inrush restraint function cannot operate below 10 % nominal current (lower limit of harmonic
filtering). An adequate time delay could be reasonable if inrush restraint is used.
The time multiplier can also be set to ∞. If set to infinity, the pickup of this function will be indicated but the
stage will not trip after pickup. If the 3I0p stage is not required at all, select address 122 DMT/IDMT 3I0 =
Definite Time when configuring the protection functions.
If under address 2225 TOC DROP-OUT the Disk Emulation is set, dropout is produced according to the
dropout characteristic, as described in subsection "Dropout Behaviour".
Inverse Time Overcurrent Stage 3I0p Pickup with ANSI Characteristics
The inverse time stage, depending on the configuration of the functional scope, address 122 (see
2.1.3.1 Setting
With the ANSI characteristics (address 122 DMT/IDMT 3I0 = TOC ANSI) the following is made available in
address 2227 ANSI CURVE:
•
Definite Inv.,
•
Extremely Inv.,
•
Inverse,
•
Long Inverse,
•
Moderately Inv.,
•
Short Inverse and
•
Very Inverse.
The characteristics and the formulas on which they are based, are listed in the "Technical Data".
If the inverse time trip characteristic is selected, please note that a safety factor of about 1.1 has already been
included between the pickup value and the setting value. This means that a pickup will only occur if a current
of about 1.1 times the setting value is present.
The current value is set in address 2221 or 2222 3I0p. The most relevant for this setting is the minimum
appearing earth fault current. Please consider that measuring tolerances may be higher with multiple meas-
uring locations due to summation errors.
The corresponding time multiplier is set in address 2224 D 3I0p. This has to be coordinated with the grading
coordination chart of the network. For earth currents with earthed network, you can mostly set up a separate
grading coordination chart with shorter delay times.
If you set a very small pickup value, consider that the inrush restraint function cannot operate below 10 %
nominal current (lower limit of harmonic filtering). An adequate time delay could be reasonable if inrush
restraint is used.
The time multiplier can also be set to ∞. If set to infinity, the pickup of this function will be indicated but the
stage will not trip after pickup. If the 3I0p stage is not required at all, select address 122 DMT/IDMT 3I0 =
Definite Time during configuration of the protection function.
If under address 2225 TOC DROP-OUT the Disk Emulation is set, a dropout in accordance with the
dropout characteristic occurs, as described in section "Dropout Behaviour".
Dynamic Cold Load Pickup
An alternative set of pickup values can be set for each stage. It may be selected automatically in a dynamic
manner during operation. The following alternative values are set for the stages here (Section
Cold Load Pickup for Time Overcurrent
for definite time overcurrent protection 3Ι0:
•
Address 2311 or 2312 for pickup value 3I0>>,
•
Address 2313 for delay time T 3I0>>,
SIPROTEC 4, 7UT6x, Manual
C53000-G1176-C230-5, Edition 09.2016
Notes), enables the user to select different characteristics.
Protection).
2.4 Time Overcurrent Protection for Phase and Residual Currents
Functions
2.6 Dynamic
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