ABB ACS880-07C, Hardware Manual

Page: 181 / 188

Resistor braking 181
16
Resistor braking
Contents of this chapter
This chapter tells how to select, protect and wire brake choppers and resistors. The
chapter also contains the technical data.
Operation principle and hardware description
The drive can be equipped with optional built-in brake chopper (+D150).
The brake chopper handles the energy generated by a decelerating motor. The chopper
connects the brake resistor to the intermediate DC circuit whenever the voltage in the
circuit exceeds the limit defined by the control program. Energy consumption by the
resistor losses lowers the voltage until the resistor can be disconnected.
Planning the braking system

Selecting the brake circuit components
1. Calculate the maximum power generated by the motor during braking ( P
max
).
2. Select a suitable drive, brake chopper and brake resistor combination for the
application from the rating table on page 185 . The braking power of the chopper must
be greater or equal than the maximum power generated by the motor during the
braking.
3. Check the resistor selection. The energy generated by the motor during a 400-second
period must not exceed the resistor heat dissipation capacity E
R
.
Note : If the E
R
value is not sufficient, it is possible to use a four-resistor assembly in
which two standard resistors are connected in parallel, two in series. The E
R
value of
the four-resistor assembly is four times the value specified for the standard resistor.