Parameter assignment/addressing
10.1 Setting the parameters
3VL molded-case circuit breakers
136 System Manual, 03/2009, 110 0110 - 02 DS 01
Parameter Setting buttons Effect on
characteristic curve
Brief description Reason
I
R
.5
.8
.7
.63
.9
.6
.45
.4
.95
1.0
x
I
n
R
I
Tripping current of the
overload protection I
R
=
0.4 to 1 x I
n
Limitation of the overload range
by setting to the operating current
of the circuit to be protected
L
t
R
2.5
17
14
20
(S)
R
t
30
25
10
8
6
4
Delay (or time-lag
class) in the overload
range. The set time is
the tripping time at 6 x
I
R
. t
R
= 2.5 to 30s
Improved selectivity in the
overload range in switching
stations with several grade levels
when the rated currents differ
only slightly
I
sd
1.5
2.5
6
5
7
sd
10
8
4
3
2
x
I
R
I
Tripping current of the
short-time delay short-
circuit protection I
sd
=
1.5 to 10 x I
R
Limitation of the short-circuit
range in which the current has to
be shut off faster than in the
overload range, but with a shorter
time delay to achieve time
selectivity to downstream
switchgear
I
2
t
sd
.4
.5
.2
.3
.4
.3
.2
.1
.1
t
sd
(S)
t
I
I
ON
2
t
2
OFF
0
Switchover from a
constant time delay to a
I
2
t characteristic curve
in the short-circuit
range I
2
t
sd
= ON or OFF
Improved selectivity with
downstream switchgear, e.g.
LVHRC fuses
S
t
sd
.4
.5
.2
.3
.4
.3
.2
.1
.1
t
sd
(S)
t
I
I
ON
2
t
2
OFF
0
Delay time of the short-
circuit protection.
Please note: The
selection between t
sd
=
constant and I
2
t
characteristic t
sd
= 0 to
0.5 s with the position
of the rotary encoding
switch
Improved selectivity of the short-
circuit protection in switching
stations with several grade levels
I
I
i
1.25
1.5
6
8
x
I
n
5
4
3
2
10
i
I
11
Tripping current of the
instantaneous short-
circuit release I
i
= 1.25
to 11 x I
n
Limitation of the short-circuit
range in which the impermissibly
high current has to be switched
off as quickly as possible. This
also takes place for the self
protection of the circuit breaker
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