Specifications

Feeder Protection SIPROTEC 7SC80
9/17SIPROTEC Compact · SIEMENS SIP 3.01 · Edition 3
Application examples
Busbar protection by overcurrent
relays with reverse interlocking
Applicable to distribution busbars
without substantial (< 0.25 x I
N
)
backfeed from the outgoing feeders.
Line feeder with load shedding
In unstable power systems (e.g.
solitary systems, emergency power
supply in hospitals), it may be neces-
sary to isolate selected consumers
from the power system in order to
protect the overall system.
The overcurrent protection functions
are effective only in the case of a
short-circuit.
Overloading of the generator can be
measured as a frequency or voltage
drop.
Fig. 9/18 Busbar protection via overcurrent relays with reverse interlocking
Fig. 9/19 Line feeder with load shedding
Busbar
Infeed
50/50N 51/51N 50/50N 51/51N 50/50N 51/51N
50/50N 51/51N
t0 = 50 ms
Reverse interlocking
I>>t0
I>> I>t
I>>
I>t
I>> I>t
52 52 52
52
Busbar
I>, I>>,
I>>> IN>>
50 50N
79M
51 51N
49 46 86
Final trip
27 81U
V<
f<
>
I2>
I>, Ip
IN>,
INTOC
52
9_11_LSA4842-us.pdf
9_12_LSA2216a-us.pdf
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