Siemens SENTRON 3WL10 - Page 63

Basic rules of parameterization and basic protection functions
 Parameter E󹪜ect on
characteris‐
tic curve
Description Cause Example
L I
r

t
I
Current setting value of the
overload protection:
I
r
=0.4…1.0 × I
n
absolute values in A
Setting of the over‐
load protection to the
load current of the cir‐
cuit to be protected
I
r
= 0.9 x I
n
(where I
n
=1000A)
Overload range as of I
r
=900A
t
r

t
I
Delay time in the overload
range The set time is the trip‐
ping time at 6×I
r
.
Use for current and
time selectivity
The set delay time t
r
of, for exam‐
ple, 10s always applies at the ref‐
erence point 6xI
r
.
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.
S I
sd

t
I
Operating current of the
short-time-delayed short-cir‐
cuit protection
I
sd
= 1.0…10xI
n
Limitation of the
short-circuit range in
which the current has
to be interrupted as
quickly as possible,
but with a de󹪝ned
time delay
I
sd
= 8xI
n
= 8000A
(at I
n
= 1000A)
Range of the short-time delay as of
8000A
t
sd

t
I
Delay time of the
short-time-delayed short-cir‐
cuit protection
Use for time selectivi‐
ty. Time delay of t
sd
can be de󹪝nite-time
or inverse-time in rela‐
tion to I²t
For example, at t
sd
=0.4s (con‐
stant): Tripping after 400m for
short-circuit values above 8000A
and below a value of I
i
I I
i

t
I
Current setting value of the
instantaneous short-circuit
protection
I
i
= 1.5… 15xI
n
Limitation of the
short-circuit range in
which the impermissi‐
bly high current has to
be interrupted as
quickly as possible
I
sd
= 12xI
n
= 12000A
(at I
n
=1000A)
Range of the instantaneous trip‐
ping on short-circuits as of 12000 A
G I
g

t
I
Current setting value of the
ground-fault protection
Line protection On ground-fault current
as of 0.1xI
n
= 100A
(at I
n
=1000A)
Tripping, for example, after a time
of t
g
=0.1s
t
g

t
I
Delay time until disconnec‐
tion
Line protection Tripping after a time of t
g
=0.1s
Description
2.9Electronic trip unit ETU
3VA27 molded case circuit breakers & 3WL10 air circuit breakers
62 Equipment Manual, 10/2023, L1V30499596002-03