In modern industrial automation, VFD (Variable Frequency Drive) motor systems are indispensable, and braking resistors act as an unsung hero in the background. Let’s dive into why this overlooked component is critical!

The Problem: Regenerative Energy and Voltage Spikes

When a motor decelerates or stops, inertia keeps the motor and its load spinning. This transforms the motor into a generator, converting mechanical energy into electrical energy. This energy flows back to the VFD’s DC bus, causing a dangerous voltage spike called “pump-up voltage.” Without control, this surge can damage sensitive components like IGBTs (Insulated Gate Bipolar Transistors) in the drive.

The Solution: Braking Resistors

Braking resistors act as an “energy sponge,” absorbing excess regenerative power and converting it into heat. This stabilizes the DC bus voltage within safe limits, protecting the VFD and motor from damage.

Applications Demanding Precision

• Cranes and Elevators: These systems require rapid, precise stopping. Braking resistors enhance braking torque by dissipating regenerative energy and creating a counter-rotational force, ensuring quick, safe halts.

• Elevators: Smooth deceleration improves passenger safety and comfort. Braking resistors prevent jerky stops, maintaining stability.

• Printing/Packaging Machines: Frequent starts and stops generate constant regenerative energy. Braking resistors manage this energy, ensuring stable operation and extending equipment lifespan.

Key Benefits of Braking Resistors

1. Voltage Suppression: Prevents pump-up voltage spikes, safeguarding VFD components.

2. Enhanced Braking Performance: Enables rapid, controlled stops for high-inertia loads.

3. Durability: Handles frequent cycling without performance degradation.

4. Safety: Critical for applications where delayed stopping risks accidents.

As industrial automation advances, braking resistors will play an even more vital role in ensuring efficiency and reliability.