Lenze 8230 Series - Brake Chopper and Braking Resistors

Technical Data
26 BA8230
2.5.2 Brake chopper The 8230 frequency inverter can additionally be equipped with a brake chopper
and braking resistors for applications involving regenerative operation, for example braking processes.
Regenerative operation of the drive occurs if negative load torque or negative
acceleration torque (braking torque) occurs in the speed range. In the majority of all
applications braking processes are the cause of regenerative drive operation.
The 8230 frequency inverter can be equipped with a power dump for this application.
Braking energy is then converted by the power dump into heat in an external resistor.
In this case the 8230 frequency inverter link voltage is limited to a fixed value, the link
current is reversed and is taken off through the power dump and the external braking
resistor.
You can estimate whether a 8230 frequency inverter with a power dump for braking is
required if you have the following drive parameters available:
• P
nom
Motor rating [kW]
• n
nom
Rated motor speed [rpm]
• n
1
Motor speed before braking [rpm]
• n
2
Motor speed after braking [rpm]
• t
B
Braking time required [s]
• t
c
Load cycle repeat time [s]
• M
L
Load torque on the motor shaft [Nm]
• J Total inertia applied to the motor shaft [kgm²]
Fig. 10: Load cycle diagram
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