Applications
3.2 Line protection applications of 3VA molded case circuit breakers
3VA molded case circuit breakers with IEC certificate
Manual, 03/2019, A5E03603177010-03
137
•
I
r
Adjustable from 0.4 to 1.0 x I
n
in absolute current values
I
r
< 50 A: in steps of 0.5 A
I
r
≥ 50 A: in steps of 1 A
•
t
r
Adjustable from 0.5 to 12 / 15 / 17 / 20 / 25 s (dependent on rated operational
current and frame size)
with a reference point of 6 x I
r
.
In steps of 0.1 s
The ETU560 LSIG and ETU860 LSIG units have a thermal memory which can be deactivat-
ed.
Short-time delayed short-circuit protection S:
•
I
sd
Adjustable from 0.6 to 9 / 10 x I
n
I
sd
< 50 A: in steps of 0.5 A
I
sd
≥ 50 A: in steps of 1 A
•
t
sd
Adjustable from 0.05 to 0.5 s
with a reference point of I
sd
= 8 x I
r
in steps of 0.01 s
The curve shape I
2
t = constant can be deactivated.
Instantaneous short-circuit protection I:
•
I
i
Sizes 100 A to 400 A:
adjustable from 1.5 to 10 / 12 x I
n
Size 630 A:
See tables above
in steps of 1 A
Ground-fault protection G:
The detection of the ground-fault current is based on a vectorial summation of the phase
currents and the neutral conductor current for 4-pole or 3-pole circuit breakers with an exter-
nal current transformer for the neutral conductor.
•
I
g
Adjustable from 0.2 / 0.25 / 0.4 / 0.6 to 1.0 x I
n
in steps of 1 A
•
t
g
Adjustable from 0.05 to 0.8 s
with a reference point of 2 x I
g
In steps of 0.01 s
An alarm threshold I
gA
between 0.2 to 1 x I
n
can also be set. in steps of 1 A
The current-dependent curve shape I
2
t = constant can be deactivated.
The ground-fault protection function G can be deactivated.
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