Siemens siprotec 7SA6 User Manual

Functions
6-104 7SA6 Manual
C53000-G1176-C133-1
Definite Time
Overcurrent
Stage 3I
0
>
The logic of the overcurrent stage 3I
0
> is the same as that of the 3I
0
>>>–stage.
3I0>>> is therefore replaced with ,!, then, Figure 6-61 also applies for 3I
0
>.
This stage operates with a specially optimized digital filter that completely suppresses
all harmonic components beginning with the 2nd harmonic. Therefore it is particularly
suited for a highly-sensitive earth fault detection. A fourth, definite time stage can be
implemented by setting the “inverse” stage (refer to the next paragraph) to a definite
time stage.
Inverse Time
Overcurrent
Stage 3I
0P
The logic of the inverse time stage in principle functions the same as the other stages.
This stage operates with a specially optimized digital filter that completely suppresses
all harmonic components beginning with the 2nd harmonic. Therefore it is particularly
suited for a very sensitive earth fault detection. The delay times in this case are
however determined by the set characteristic (Parameter ,(&&XUYH), the magnitude
of the earth current and the time multiplier ,S7LPH'LDO (Figure 6-62). A pre-
selection of the optional characteristics was already done during the configuration of
the protection functions. Furthermore, an additional fixed delay $GG7'(/$< may
be selected. The optional characteristics are illustrated in the technical data of Section
10.5.
Figure 6-62 shows the logic diagram. As an example, the setting addresses for the IEC
curves are shown in the diagram. The different setting addresses are referred to in
more detail in the setting information (Sub-section 6.5.2)
It is also possible to implement this stage as a further definite time stage. In this case
,S3,&.83 is the pick up threshold and $GG7'(/$< the definite time delay. The
inverse time characteristic is then effectively bypassed.
Figure 6-62 Logic diagram of the 3I
0P
–stage (inverse time overcurrent protection), for example IEC curves
I
E
3I
0P

Yes
No
Reverse
Forward
Non-Directional
„1“
≥1
&
&
inrush
stabilization
direction
determination
forwards
reverse
&
&
Yes
No
,S627)7ULS

Yes
No
,S7HOHS%,
permissive
teleprot.
switch on
to fault
≥1
EF 3I0p TRIP
T0
 627)7LPH'(/$<
&
&
PICKUP
PICKUP+DIRECT.

&
627)2S0RGH
t
3I
0

T0


1309 >EF BLOCK 3I0p

1357
EF 3I0p Pickup
1369


≥1
>EF Inst TRIP
$GG7'(/$<
,(&&XUYH
,S3,&.83
2SPRGH,S
,S,QUXVK%ON
3I0p Time Dial
Inactive
FNo1310

Siemens siprotec 7SA6 Specifications

General

Brand	Siemens
Model	siprotec 7SA6
Category	Relays
Language	English