Bosch REXROTH EFC 3600 Instruction Manual page 63

DOK-RCON01-REX*F*UL***-IN01-EN-P
Rexroth Frequency Converters
● If a resistance lower than the recommended value (and no less than the
minimum resistance) is used, contact the agent or manufacturer for cal‐
culation of resistance power.
● Safety and flammability of surrounding conditions shall be considered.
Keep all items at least 10 cm away from the braking resistor.
● A braking resistor can not work overload for a long time. 10 times of rat‐
ed load should not exceed 5 seconds.
● There could be smoking for the first use of the braking resistor since or‐
ganic silicon is used on the surface which is normal and does not affect
the performance of the braking resistor.
Brake resistor selection
Braking resistors with different power ratings are available to dissipate braking energy
when the frequency converter is in generator mode. The adjacent tables below list the
optimal combination of frequency converter, brake chopper and braking resistor and
the number of components required to operate one frequency converter with respect to
a given moderating ratio OT.
● The recommended resistance of the braking resistor in the table is con‐
figured assuming 100 % braking torque. If the actually needed torque is
not 100 %, the resistance of the braking resistor in the table should be
adjusted in inverse proportion, i.e. how much the braking torque increa‐
ses based on 100%, the resistance of the braking resistor should de‐
crease by the same amount, and vice versa.
● When selecting braking resistor R
flows through the resistor is less than the current output ability of the
brake chopper. The current I
lated by formula I
of the brake chopper.
● After the adjustment of the resistance of braking resistor, the power of
braking resistor should be also adjusted appropriately. The power can
be calculated by formula P
condition, the braking ratio OT % can be selected to reduce the power
of braking resistor reasonably for intermittent braking load. The power
of braking resistor can be calculated by formula PR=K×P
which k is the derating coefficient of braking resistor. The selection of
the braking torque should be in general smaller than 150 % of the rated
motor torque, or please consult the technical support for more informa‐
tion.
, make sure the current I
b
through the braking resistor can be calcu‐
c
=U /R , in which U
c d b
=U 2 /R
max d b
Bosch Rexroth AG
is the braking operating voltage
d
. According to the actual working
Accessories
which
c
× OT%, in
max
61/65