NBRA-659C 1-phase brake chopper units

Product overview
ACS880-604 is an air-cooled brake chopper unit. It includes an NBRA brake chopper
module or two parallel-connected NBRA brake chopper modules.
Operation principle
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.
Typically, a drive system is equipped with a brake chopper(s) if:
• high capacity braking is needed and the drive cannot be equipped with a regenerative
supply unit
• a backup for the regenerative supply unit is needed.
Standard resistors are available from ABB for each brake chopper module.

NBRA-659C

The brake chopper module must be installed in an upright position. The degree of
protection of the module is IP00. Take this into account when selecting the installation site.
Installation in a cabinet is highly recommended.
Obey the general ACS880 multidrive module cabinet installation instructions given in
Cabinet design and construction instructions for ACS880 multidrive modules
(3AUA0000107668 [English]). In addition, observe these restrictions:
• The brake unit can be grounded to the frame through the mounting screws if the
galvanic connection to PE (protective earth) is good enough.
• Leave 150 mm (5.91 in.) free space below and above the brake chopper module.
• Leave enough space for the fuses and the cooling fan.
• To prevent the module from overheating, do not install it directly above the brake
resistors.
The maximum lengths of the chopper and resistor cables are 5 m and 10 m, respectively.
Required tools
Make sure that you have these tools available:
• drill with suitable bits
• screwdriver and/or wrench with a set of suitable bits
• mounting screws (M6).