•
Extremely Inv. (extremely inverse, type C according to IEC 60255-3), and
•
Long Inverse (longtime, type B according to IEC 60255-3).
The characteristics and the equations on which they are based, are listed in the “Technical Data”.
If the inverse time trip characteristic is selected, it must be noted 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 under address 2021 or 2022 Ip. The maximum operating current is of primary impor-
tance for the setting. Pickup due to overload should never occur, since the device, in this modem, operates as
fault protection with correspondingly short tripping times and not as overload protection.
The corresponding time multiplier is accessible via address 2023 T Ip. It must be coordinated with the time
grading of the network.
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 Ip stage is not required at all, select address 120 DMT/IDMT Phase =
Definite Time when configuring the protection functions.
If under address 2025 TOC DROP-OUT the Disk Emulation is set, dropout is produced in accordance with
the dropout characteristic, as set out in the functional description of the inverse time overcurrent protection in
section “Dropout Behaviour”.
Inverse Time Overcurrent Stages Ι
p
with ANSI Curves
The inverse time stage, depending on the configuration of the functional scope enables the user to select
different characteristics.
With the ANSI characteristics (address 120 DMT/IDMT Phase = TOC ANSI) the following is made available in
address 2026 IEC 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 “Technical Data”.
If the inverse time trip characteristic is selected, it must be noted 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 of the setting value is present.
The current value is set under address 2021 or 2022 Ip. The maximum operating current is of primary impor-
tance for the setting. Pickup due to overload should never occur, since the device, in this modem, operates as
fault protection with correspondingly short tripping times and not as overload protection.
The corresponding time multiplier is set at address 2024 D Ip. It must be coordinated with the time grading
of the network.
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 Ip stage is not required at all, select address 120 DMT/IDMT Phase =
Definite Time.
If Disk Emulation is set in address 2025 TOC DROP-OUT, dropout is produced according to the dropout
characteristic. For further information refer to section “Dropout Behaviour” (see Section 2.4.1 General, margin
heading “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 (see Section 2.6 Dynamic Cold Load Pickup for Time Overcurrent Protection).
For the stages the following alternative values are set:
Functions
2.4 Time Overcurrent Protection for Phase and Residual Currents
SIPROTEC 4, 7UT6x, Manual 149
C53000-G1176-C230-5, Edition 09.2016
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