Siemens SENTRON 3VL160X System Manual page 121

Parameter Setting buttons
G I /t
g g
For LCD ETUs, the ST function must be set to the value "disabled" for t
1)
Setting of the protection parameter for line and generator protection
The settings are variable depending on the trip unit (ETU10, ETU12, ETU20, ETU22, LCD-
ETU40 and LCD-ETU42). The following parameters can be set depending on the version:
L overload release I
The overload release I
takes place with the help of the left rotary encoding switch I
(example: I
rotary encoding switch).
Delay time t
The delay time (or time-lag class) t
time is the tripping time at 6 x I
can be achieved in the overload range, for example, when the rated current range does not
differ much.
S short-time delayed short-circuit protection I
The short-time delay short-circuit protection can be set with regard to the tripping value of
the current I
and can be set between 1.5 to 10 x I
Delay time t
Depending on the requirements and on the trip unit, selectivity to the other molded case
circuit breakers can be achieved with appropriate selection of the delay time t
encoding switch is in the "ON" range, this means the delay time is current-dependent. The I
value is constant. For example, the higher the current, the faster the circuit breaker will trip
(equivalent to the overload release I
current-independent, that is, constant. If the current reaches the set value I
breaker trips after the set time t
not important. The set time is the tripping time at 8 x I
3VL IEC molded case circuit breakers
System Manual, 11/2013, 110 0110 - 02 DS 03
Effect on
characteristic curve
:
R
is set to the operating current I
R
= 250 A, I = 315 A => setting factor 250 / 315 = 0.79 corresponds to 0.8 on the
B n
:
r
. In this way, selectivity to other molded case circuit breakers
r
and the delay time t
sd
:
sd
. The degree to which the current exceeds the value I
sd
Brief description
Tripping current and
time delay of the
ground-fault protection
I = Off, 1 or 0.6 x I
g n
Off, 0.1 s or 0.3 s
= 0.
sd
B
can be set using another rotary encoding switch. The set
r
:
sd
. I refers to the tripping value of the overload release I
sd sd
(depending on the molded case circuit breaker).
R
). In contrast, the delay time in the "OFF" position is
R
.
r
Parameter assignment / addressing
9.1 Setting the parameters
Cause
Protection from short-circuit to
ground and thus prevention of
arcs. Ground-fault protection is
t = part of the fire protection.
g
of the circuit to be protected. This
that is set to the factor I
R
sd
, the circuit
sd
/I
B n
R
. If the rotary
t
2
is
sd
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