REXROTH EFC3600 Series, Инструкция по эксплуатации

Страница: 85 / 90

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 fre-
quency converter with respect to a given moderating ratio OT.
●
The recommended resistance of the braking resistor in the table
is configured assuming 100 % braking torque. If the actually nee-
ded 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 increases based on 100%, the resistance of
the braking resistor should decrease by the same amount, and
vice versa.
●
When selecting braking resistor R
b
, make sure the current I
c
which
flows through the resistor is less than the current output ability of
the brake chopper. The current I
c
through the braking resistor can
be calculated by formula I
c
=U
d
/R
b
, in which U
d
is the braking ope-
rating voltage 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
max
=U
d
2 /R
b
. According to
the actual working condition, the braking ratio OT % can be selec-
ted to reduce the power of braking resistor reasonably for inter-
mittent braking load. The power of braking resistor can be calcu-
lated by formula P
R
= K × P
max
× OT %, in 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 tor-
que, or please consult the technical support for more information.
Bosch Rexroth AG
Accessories
DOK-RCON01-REX*F*UL***-IN10-EN-P
65/69