A5E00817857-01
9
Operating Instructions
English
For the VT400 circuit breaker, there are different versions available:
- L protection fixed (I
r
= 1.0 x I
n
) and I protection fixed.
- L protection adjustable (I
r
= 0.7 - 1.0 x I
n
) and I protection fixed. An illustration of the trip unit with adjustable L can be seen
in
Figure (19). The ranges of current settings are described in Table
(20).
- ETU, LSI adjustable, I
r
= 0.4 - 1.0 x I
n
.
The permissible load capacity of the circuit breaker is dependent on the ambient temperature in its immediate vicinity, see Table (18).
In the case of thermal magnetic ETUs, the load is independent of the temperature.
(18)
Setting the long-time delay overload (L) and short-circuit instantaneous (I) protection
Load capacity at various ambient temperatures
Rated current
of frame size
Ambient temperature
I
n
+10 °C +20 °C +30 °C +40 °C +50°C +55 °C +60 °C
400 A
1.13
1.11
1.04
1.0 I
n
0.92
0.88
0.85
(19) VT400 TM trip unit with adjustable I
r
/ VT400 Front of ETU
Switch for long-time delay
setting I
r
Current beam
indication of operation
Socket for
test kit
Alarm indication
of fault
Indication of power
and self-diagnosis
Switch for current settings I
sd
, I
i
Switch for pre-alarm setting I
LC
Characteristic curve
of overcurrent
Switch for ground fault current setting
(only available for 4-pole versions)
Min
Max
Adjustable knob for I
r
