Definition
A brake resistor dissipates, as heat, the excess electrical energy a motor regenerates during rapid deceleration: energy that would otherwise accumulate in the drive's DC link and risk triggering a DC-link overvoltage fault. It is switched into the circuit by the drive when DC-link voltage rises toward its limit, converting the surplus energy to heat rather than letting it damage components.
Key facts
- Dissipates excess regenerated energy as heat, directly preventing DC-link overvoltage during rapid deceleration events.
- Switched into the circuit by the drive's control logic when DC-link voltage approaches its limit, not continuously active.
- Sizing must match the application's expected regenerative energy and deceleration frequency: undersized resistors can overheat.
- An alternative or complement to adjusting deceleration ramp time as a way of managing regenerative energy.
How does Brake resistor work or appear?
A brake resistor works by being switched into the drive's DC-link circuit when voltage there rises toward its safe limit, providing a path for excess regenerated energy (typically from a motor decelerating faster than the load can absorb) to be dissipated as heat rather than accumulating and risking a DC-link overvoltage fault.
What should technicians inspect for Brake resistor?
DC-link overvoltage is the fault condition that occurs when regenerated energy exceeds what the system can absorb. A brake resistor is one of the standard solutions for that fault: it provides a controlled path to dissipate that excess energy, either alongside or as an alternative to reducing the deceleration rate.
FAQ
Frequently asked questions
What role does a brake resistor play in energy dissipation?
A brake resistor dissipates excess electrical energy regenerated during rapid motor deceleration as heat, preventing that energy from accumulating in the drive's DC link and triggering an overvoltage fault.
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