Siemens MICROMASTER 440 Operating Instructions Manual page 144

3 Functions
NOTE
The switch-on threshold V
on P1254
V
DC chopper
External braking modules (chopper units) including braking resistor can be used
with all of the sizes, FS FX and FS GX. When engineering the system, the
particular braking module / resistor must be taken into consideration.
WARNING
Braking resistors, which are to be mounted on MICROMASTER 440, must be
designed so that they can tolerate the power dissipated.
If an unsuitable braking resistor is used there is a danger of fire and that the
associated drive inverter will be significantly damaged.
The chopper control, integrated in the drive converter is designed for the
braking resistor value assigned in Catalog DA51.2,
e.g.: MICROMASTER 440
brake resistor
brake resistor value
A brake resistor with a lower resistance value will destroy the drive converter.
In this case, an external braking unit must be used.
When operational, the temperature of braking resistors increases – do not
touch ! Ensure that there is sufficient clearance around the unit and there is
adequate ventilation.
A temperature protection switch must be used to protect the units against
overheating.
144
of the dynamic resistor braking is dependent
DC chopper
≠
(P1254 = 0) V
DC chopper
6SE6440-2UD23-0BA1
6SE6400-4BD12-0BA0
160 Ω
≠
(P1254 0).
MICROMASTER 440
6SE6400-5AW00-0BP0
Issue 10/03
Operating Instructions