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3VT3 Molded Case Circuit Breakers up to 630 A
Overcurrent releases
4/16
Siemens LV 36 · 2008
4
■
Overview
The electronic overcurrent release consists of a separate and
interchangeable unit, which is supplied with the 3VT3
switching unit. By exchanging the overcurrent release, the range
of the circuit breaker’s rated current can be easily changed.
Overcurrent releases for 3VT3 switching units are produced in
current values of
I
n
= 250, 400 and 630 A. The ETU LP releases
are produced with rated currents of 250, 315, 400, 500 and
630A. The releases (including regulation of -60%) cover a
current range from 100 to 630 A.
Tripping characteristics
Depending upon the needs for adjusting the release’s tripping
characteristic to the protected device and to the variability of the
characteristic with regard to selectivity, the following releases
are available:
ETU LP
They have one type of characteristic and fixed
I
n
and
I
rm
settings.
ETU DP
They have one type of characteristic with adjustable
I
r
and
I
rm
.
ETU MP
They have more kinds of characteristics with adjustable
I
r
, t
r
and
I
rm
.
ETU MPS
They have more kinds of characteristics with adjustable
I
r
, t
r
,
I
sd
and t
sd
.
ETU LP, DP, MP and MPS overcurrent releases are intended for
3-pole 3VT3 763-.AA36-0AA0 switching units and 4-pole
3VT3 763-.AA46-0AA0 switching units with disconnecting of the
N pole.
ETU DPN
They are intended for 4-pole 3VT3 763-.AA56-0AA0 switching
units with protected N pole. They have more characteristics with
adjustable
I
r
, t
r
,
I
rm
and
I
N
.
NSO0_00502
t
I
L
I
NSO0_00353
t
I
L
I
I
r
I
i
t
r
NSO0_00354
t
I
L
I
I
r
50 ms
0 ms
I
i
NSO0_00214
t
I
L
S
I
I
r
I
sd
t
sd
t
r
NSO0_00531
t
I
L
I
I
r
t
r
I
i
I
N