Allowed Braking Power And Need For A Brake Resistor - ABB ACS800 Application Manual

Allowed braking power and need for a brake resistor

1. For each drive check that the braking power does not exceed the allowed braking
power. See
2. For the common DC system check whether it needs to be equipped with an
additional brake chopper and resistor. This is the case if the total power of the
common DC system is negative at any point of the duty cycle [i.e. braking motor(s)
regenerate more power to DC link that can be consumed by other motors]. See the
figure below which shows the duty cycles of three drives and the sum, the common
DC duty cycle. A brake chopper and a resistor is needed to dissipate the surplus
braking energy (the shaded areas).
Drive A
duty cycle
Drive B
duty cycle
Drive C
duty cycle
Common DC
duty cycle
Calculation of the allowed braking power
P
P
P
P
below.
t
t
t
t
15
Design