Siemens SENTRON 3WL10 Manual page 69

Basic rules of parameterization and basic protection functions
Parameter Effect on
characteris-
tic curve
L I
r
t
r
S I
sd
t
sd
I I
i
G I
g
3VA27 molded case circuit breakers & 3WL10 air circuit breakers
Manual, 10/2018, 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 overload
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 protection
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 mple, 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 depen-
dency.
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 (constant): Tripping after 400 m
sd
can be definite-time for short-circuit values above
or inverse-time in 8000 A 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 trip-
sibly high current has
ping 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
Description
2.8 Electronic trip unit ETU
= 0.9 x I (where I =1000A)
n n
= 900 A
r
of, for exa-
r
.
r
= 8 x I = 8000 A
n
= 1000 A)
n
= 0.4 s
sd
= 12 x I = 12000 A
n
= 1000 A)
n
= 100 A
n
= 1000 A)
n
= 0.1 s
g
i
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