3.1.23 When does a frequency converter need a braking resistor?
A frequency converter requires a braking resistor if the load it drives brakes dynamically or decelerates quickly, resulting in energy being fed back into the converter.
Detailed explanation:
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Renewable energy:
When a motor decelerates, it converts kinetic energy back into electrical energy. This energy flows into the DC bus of the frequency converter. -
Avoid overloading:
If the feedback is too high, the DC link voltage can rise and damage the inverter. -
Use of a braking resistor:
A braking resistor converts the excess energy into heat, allowing the inverter to brake safely without being overloaded.
Typical applications:
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Conveyor belts with heavy loads that need to be stopped quickly
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Cranes, elevators, lifting devices
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Machines with high inertia, e.g. roller conveyors, screw conveyors
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Dynamic process machines where rapid stopping is necessary
In short:
A braking resistor is needed when the motor feeds back energy during braking that the frequency converter cannot absorb on its own.
