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Technical Data
4.16 Backup Time Overcurrent Protection
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
614
4.16 Backup Time Overcurrent Protection
Operating Modes
Characteristics
High-set Current Stages
As emergency overcurrent protection or back-up overcurrent protection
Emergency time overcurrent protection with dif-
ferential and distance protection
Effective when the differential protection system is blocked (e.g.
because of a failure of the device communication) and the distance pro-
tection system is additionally blocked, e.g. because of a trip of the
voltage transformer mcb (via binary input), a measuring voltage failure
or a pickup of the fuse failure monitor
Emergency overcurrent protection with differen-
tial protection (distance protection not configured) Effective when the differential protection system is blocked (e.g.
because of a failure of the device communication)
Emergency time overcurrent protection with dis-
tance protection (differential protection not config-
ured) Effective when the distance protection system is blocked, e.g. because
of a trip of the voltage transformer mcb (via binary input), a measuring
voltage failure or a pickup of the fuse failure monitor
Back-up overcurrent protection operates independent of any events
Definite dime stages (definite) I
Ph
>>>, 3 I
0
>>>, I
Ph
>>, 3 I
0
>>, I
Ph
>, 3 I
0
>
Inverse time stages (IDMT) I
P
, 3 I
0P
; one of the characteristics according to
Figure 4-2 to 4-4 (see Technical Data Section „Earth Fault Protection“)
can be selected
Pickup value I
Ph
>> (phases) for I
N
= 1 A 0.10 A to 25.00 A
or
∞
(ineffective)
Increments 0.01 A
for
I
N
= 5 A 0.50 A to 125.00 A
or
∞
(ineffective)
Pickup value 3 I
0
>> (earth) for I
N
= 1 A 0.05 A to 25.00 A
or
∞
(ineffective)
Increments 0.01 A
for
I
N
= 5 A 0.25 A to 125.00 A
or
∞
(ineffective)
Pickup value
I Ph
>> (phases) 0.00 s to 30.00 s
or
∞
(ineffective)
Increments 0.01 s
Delay T
3
I
0
>> (earth) 0.00 s to 30.00 s
or
∞
(ineffective)
Increments 0.01 s
Dropout ratio Approx. 0.95 for I / I
N
≥
0.5
Pickup times (fast relays/high-speed relays) Approx. 25 ms/20 ms
Dropout times Approx. 30 ms
Tolerances Currents 3 % of setting value or 1 % nominal current
Times 1 % of setting value or 10 ms
The set times are pure delay times