2.9 Backup Time Overcurrent Protection
111
7SD610 Manual
C53000-G1176-C145-4
2.9.3 Setting Notes
General During configuration of the scope of functions for the device (address 126) the avail-
able characteristics were determined. Depending on the configuration and the order
variant, only those parameters that apply to the selected characteristics are accessible
in the procedures described below.
Address 2601 is set according to the desired mode of operation of the overcurrent
protection: Operating Mode = ON means that the time overcurrent protection oper-
ates independently of the other protection functions, i.e. as a backup time overcurrent
protection. f it is intended to work only as an emergency function in case of a trans-
mission failure, set Only Emer. prot. Finally, it can also be set to OFF.
If not all stages are required, each individual stage can be deactivated by setting the
pickup threshold to ∞. But if you set only an associated time delay to ∞ this does not
suppress the pickup signals but prevents the timers from running.
The I>>> stage is effective even if the operating mode of the time overcurrent protec-
tion has been set to Only Emer. prot and „>I-STUB ENABLE“ is released.
One or several stages can be set as instantaneous tripping stages when switching
onto a fault. This is chosen during the setting of the individual stages (see below). To
avoid a spurious pickup due to transient overcurrents, the delay SOTF Time DELAY
(address 2602) can be set. Typically, the presetting of 0 is correct. A short delay can
be useful in case of long cables for which high inrush currents can be expected, or for
transformers. The time delay depends on the severity and duration of the transient
overcurrents as well as on which stages were selected for the fast switch onto fault
clearance.
Directional Stages The directional stages require additional settings.
At address 2603Direct. 3I0 you set the measuring variables to be used for the
direction determination of the earth current stages.
If U0/I0 or U2/I0 has been set (default setting), negative sequence or zero se-
quence values can be used. Negative sequence system values are used if they are
larger then the respective zero sequence system values. If the measuring variables of
both systems are unavailable, the directional 3I0>stages are blocked.
If with U0/I0 has been set, the current zero sequence values 3U
0
and 3I
0
are used.
If the zero sequence voltage is too small for a direction measurement, the directional
3I0>stages are blocked.
If with U2/I2 has been set, the current negative sequence values 3U
2
and 3I
2
are
used. If the negative sequence voltage is too small for a direction measurement, the
directional 3I0>stages are blocked.
In addition, at address 2680 Direction Iph> or 2683 Direction 3I0> set the
pickup direction for the directional stages I>ger and 3I0ger. The settings Non-
Directional (presetting), Forward, and Reverse are possible.
In address2688Direction IP or 2693Direction 3I0P you set the pickup direc-
tion for the directional stages IPger and 3I0Pger. Settings Forward (default setting)
and Reverse are possible.
High-current ele-
ments I
ph
>>, 3I
0
>>
The I>> stages Iph>> (address 2610) and 3I0>> PICKUP (address 2612) together
with the I> stages or the I
p
stages result in a two-stage characteristic. Of course, all
three stages can be combined as well. If one stage is not required, the pickup value
has to be set to ∞. The I>> stages always operates with a defined delay time.
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