Siemens SENTRON 3WL10 Series Manual page 51

Basic rules of parameterization and basic protection functions
Parameter Effect on char-
acteristic curve
L I
r
t
r
S I
sd
t
sd
I I
i
G I
g
t
g
Air circuit breaker 3WL10
Manual, 11/2017, L1V30499596002-01
Description
Current setting value of
the overload protection:
I =0.4...1.0 × I
r n
absolute values in A
Delay time in the over-
load range The set time
is the tripping time at
6 × I .
r
Operating current of the
short-time-delayed short-
circuit protection
I = 1.0 ... 10 x I
sd n
Delay time of the
short-time-delayed
short-circuit protection
Current setting value
of the instantaneous
short-circuit protection
I = 1.5 ... 15 x I
i n
Current setting value of
the ground-fault protec-
tion
Delay time until
disconnection
Cause Example
Setting of the over- I
r
load protection to the
Overload range as of I
load current of the
circuit to be protected
Use for current and The set delay time t
time selectivity ple, 10 s always applies at the
reference point 6 x I
In this case, it is therefore
6 x 900 A = 5400 A
The tripping characteristic in
the overload range can be plotted
in the same way as for I²t
dependency.
Limitation of the I
sd
short-circuit range in (at I
which the current has
Range of the short-time delay as
to be interrupted as
of 8000 A
quickly as possible,
but with a defined
time delay
Use for time selectivi- For example, at t
ty. Time delay of t stant): Tripping after 400 m for
sd
can be definite-time short-circuit values above 8000 A
or inverse-time in and below a value of I
relation to I²t
Limitation of the I
sd
short-circuit range in (at I
which the impermis-
Range of the instantaneous
sibly high current has
tripping on short-circuits as of
to be interrupted as
12000 A
quickly as possible
Line protection On ground-fault current
as of 0.1 x I
(at I
Tripping, for example, after a time
of t
Line protection Tripping after a time of t
Description
2.4 Electronic trip unit ETU
= 0.9 x I (where I =1000A)
n n
= 900 A
r
of, for exam-
r
.
r
= 8 x I = 8000 A
n
= 1000 A)
n
= 0.4 s (con-
sd
i
= 12 x I = 12000 A
n
= 1000 A)
n
= 100 A
n
= 1000 A)
n
= 0.1 s
g
= 0.1 s
g
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