Dynamic Brake & Resistor Calculator

Chopper, Resistor, Regenerating, AFE.

Current, Voltage, Duty Cycle, Kw, Hp.
DC=DC pulse, AC=AC rms, Duty Cycle= %, A=Amp, V=Volt

To save energy cost, replace resistor choppers with regenerative brakes.

Any questions? please contact our service engineers.

Before using this Dynamic Brake Calculator:
Important !
1, What is the Grid Voltage?
2, What is the horse power of the motor?
3, Is the Drive System with transmission Gears or without Gears?
4, What type is the motor? Induction or PM permanent magnet motor？
5, How long does each single braking last?
Duty cycle:  frequency of braking, or how long each braking takes.

How to modify your calculation:

Dynamic Braking Application Guidelines

1. Chopper Rated Current
   Chopper rated current is specified in DC. Choppers operate at different duty cycles, so always ensure the chopper’s duty cycle is matched to the actual operating duty cycle of the load.
2. Regenerative Dynamic Brake Rated Current
   Regenerative Dynamic Brake rated current is specified in AC. Because regenerative dynamic brakes operate at different duty cycles, always ensure the brake’s duty cycle is suitable for the actual load operating conditions.

3. Power Resistor Peak Capacity
   Power resistors can typically withstand 2–5 times their rated current for a short period, depending on the resistor specifications and application. This short-term surge capacity can help reduce overall system costs.

   For example, a 1 kW resistor may be capable of handling 2–5 kW of peak power when the braking duration is less than 2 seconds. Always confirm the manufacturer’s specifications before applying this approach.

4. Choose the Right Size—Not Simply the Largest
   Bigger is not always better. An oversized braking component can increase equipment and installation costs without providing additional benefits. Always select a dynamic braking solution that is properly sized for the actual load and operating conditions.

Always review the product specifications and application requirements before selecting or installing a dynamic braking system.

Regenerative Brake from $199

Dynamic Brake Calculator, get results in seconds.

Don’t need to be an engineer, and don’t need precise information. A simple calculation will cover 90% of engineering applications.

Dynamic Brake Calculator by CanadaVFD.

We recommend VFD series Regenerative Dynamic Brake from $199

Read More About Dynamic Braking

Dynamic braking occurs when an electric motor operates as a generator while slowing down a running load, such as an elevator or centrifuge. When the generated electrical energy is dissipated as heat through braking resistors, the process is commonly referred to as rheostatic braking. When the generated energy is returned to the electrical supply or grid, it is referred to as regenerative braking.

Dynamic braking reduces wear on mechanical, friction-based braking components. Regenerative braking can also improve overall energy efficiency by recovering energy that would otherwise be dissipated as heat.

Dynamic braking is used in a wide range of applications, including railcars, light-rail vehicles, electric trams, elevators, escalators, centrifuges, servo drives, hoists, and cranes. As energy efficiency becomes increasingly important, regenerative braking is also being adopted in more motor and drive applications to reduce energy consumption.

Principle of Operation: Dynamic Braking

During braking, the motor operates as a generator. The mechanical energy from the rotating load drives the motor, causing it to generate electrical energy.

In a conventional dynamic braking system, the generated electrical energy is directed to braking resistors, which convert the energy into heat. The resistors provide an electrical load that creates a braking torque, causing the motor and connected load to slow down.

By controlling the motor’s electrical excitation and the amount of resistance in the braking circuit, the braking torque can be adjusted to provide controlled deceleration and bring the load to a stop.

In a VFD-based drive system, dynamic braking is typically accomplished using either a dynamic braking chopper and resistor or a regenerative dynamic brake. A regenerative dynamic brake can recover approximately 80–90% of the available mechanical energy, depending on the application and operating conditions.

Disclaimer

The Dynamic Brake Calculator is provided for informational purposes only. The calculated values should not be used as the sole basis for a practical engineering application.

Before selecting or installing a dynamic braking system, a qualified engineer should review and verify all calculations, parameters, equipment ratings, and application requirements.

About braking resistors, click here

Dynamic Brake Calculator by CanadaVFD, 2025