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Operation principle and hardware
description
Contents of this chapter
This chapter describes a typical drive system and the operation principle and construction
of the brake chopper module.
Product overview
The ACS880-604 is an air-cooled brake unit as modules. The brake unit as modules range
contains components for building the brake unit(s) to be used in a common DC bus system
drive. The brake unit as modules includes a brake chopper module or several
parallel-connected brake chopper modules. The brake chopper module is actually a
three-phase inverter module (ACS880-104) that is connected and controlled in a particular
way: the input of the module is connected to the DC bus – like in the inverter use – but each
output phase connects to a resistor of its own.
Operating principle
The brake chopper handles the energy generated by a decelerating motor. The extra energy
increases the DC link voltage. The chopper connects the brake resistors 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 resistors can be
disconnected.
When to use resistor braking
Typically, a drive system is equipped with a brake chopper if
•
high capacity braking is needed and the drive cannot be equipped with a regenerative
supply unit
Operation principle and hardware description 15
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