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3VT3 Molded Case Circuit Breakers up to 630 A
Overcurrent releases
4/20
Siemens LV 36 · 2008
4
Adjustable specifications
Overcurrent releases ETU MP-Motors
• Direct protection for motors and generators
• Possibility for protecting lines and transformers
The 3VT9 3..-6AP00 release is intended for 3VT3763-.AA36-
0AA0 and 3VT3763-.AA46-0AA0 switching units. The operation
of the release is controlled by a microprocessor. The release is
equipped with a thermal memory that can be disabled by turn-
ing a switch on the front panel from position T
(t)
to position T
(0)
.
After disabling of the thermal memory, the thermal release re-
mains active.
When one or two phases fail (due to current greater than
I
r
in the
remaining phases), in the M-characteristic mode, the switch will
open with a 4 s delay (so-called undercurrent release).
Another parameter for adjusting the release consists of the rated
current and short-circuit tripping level. The time delay of the
short-circuit release can be set to 0 or 50 ms. The operational
state 70% of
I
r
is signalled by an LED indicator that flashes green
in a 1.5 s interval. As the load grows, the blinking frequency of
the diode increases. In case of a load larger than 110% of
I
r
, this
LED will turn red and just before tripping will begin to blink red.
On the lower part of the release cover are two photocells for
communicating with the prospective signalling unit.
The releases have tripping characteristics especially designed
for practical purposes that provide for optimal exploitation of
transformers up to 1.5
I
r
. A total of 8 characteristics can be set
on the release. Mode “M” provides 4 characteristics suitable for
protecting motors and in mode “TV” are 4 characteristics for pro-
tecting transformers and lines. The shape of each characteristic
can be changed using a selector switch.
Order No.
Rated
current
I
n
Overload
protection
I
r
Restart
Instanta-
neous
short
circuit pro-
tection
I
i
A
A
100
110
115
125
137
144
160
3VT9 325-6AC00 250
172
T
(0)
4 x
I
r
180
T
(t)
12,5 x
I
r
190
200
210
220
231
243
250
160
172
180
190
200
210
220
3VT9 340-6AC00 400
231
T
(0)
4 x
I
r
243
T
(t)
12,5 x
I
r
250
275
290
315
345
360
400
250
260
275
290
305
345
315
360
T
(0)
4 x
I
r
3VT9 363-6AC00 630
400
T
(t)
12,5 x
I
r
435
455
480
500
550
575
630