Specifications

Overcurrent Protection SIPROTEC 7SJ80
4/16 SIPROTEC Compact · SIEMENS SIP 3.01 · Edition 3
Application examples
Synchrocheck
Where two system sections are inter-
connected, the synchrocheck determi-
nes whether the connection is permis-
sible without danger to the stability
of the power system. In the example,
load is supplied from a generator
to a busbar through a transformer.
The vector group of the transformer
can be considered by means of a
programmable angle adjustment, so
that no external adjustment elements
are necessary. Synchrocheck can be
used for auto-reclosure, as well as for
control functions (local or remote).
Protection of a transformer
The high-current stage enables a cur-
rent grading, the overcurrent stages
work as backup protection to subordi-
nate protection devices, and the over-
load function protects the transformer
from thermal overload. Low-current,
single-phase faults on the low-
voltage side, which are reproduced
in the opposite system on the high-
voltage side, can be detected with
the unbalanced load protection. The
available inrush blocking prevents
pickup caused by the inrush currents
of the transformer.
Fig. 4/16 Measurement of busbar and feeder voltage for synchronization
Fig. 4/17 Typical protection concept for a transformer
Transformer
Busbar
Closing Signal
VT1
AR
Synchrocheck
Automatic reclosing
G
Infeed
81
25
V2
Local/remote
control
SYN
1)
2)
1)
2)
2
1
52
Busbar
50 51
50N
49 46
51N
59
59-1 PU
46
Busbar
TRIP
87
e.g.
7UT61
50N
IN>, IN>>
51N
TRIP
High-voltage
Medium-voltage
Unbalanced fault
typical Feeder
Inrush blocking
,t
I2>>t, I2>t
IN>t, IN>>t, INTOC
IN>, IN>>
IN>t, IN>>t,
INTOC
>t
I>t, I>>t, Ip I2>t, I2>>tI>, I>>
50 51
I>t, I>>t, IpI>, I>>
52
52 52 52 52
52
*
52
52
4_16_LSA4114-us.pdf
4_17_LSA2203b-us.pdf
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