In industrial automation systems, high-speed motor deceleration can sometimes become a major challenge, especially when users expect faster stop times without causing overvoltage faults or damaging equipment.
Recently, we encountered an interesting case involving a customer using a high-speed spindle motor, and the final result was very satisfying.
The Problem: Deceleration Was Too Slow
The customer was using a 1PH8105 spindle motor running at 6000 RPM. Their original setup allowed the motor to decelerate from 6000 RPM to stop in approximately 10 seconds.
However, the customer felt that this was too slow for their application and requested a much faster stop time — ideally within 1 second.
Before reaching us, they had already spent almost one month troubleshooting the issue but could not find an effective solution.
The main concern was clear:
- Faster deceleration could easily trigger DC bus overvoltage
- Excess braking energy might damage components
- Standard parameter adjustments were not enough
Our Technical Analysis
After understanding the application and reviewing the system details, we quickly focused on the braking circuit.
We discovered that the machine did not include an external braking resistor, which explained why aggressive deceleration settings could not be achieved safely.
To solve the issue, we recommended:
- Adding a suitable braking resistor
- Adjusting drive parameters for fast deceleration
- Optimizing braking response while protecting the system
Based on our calculations and experience, we selected a 3kW braking resistor (33Ω).
Installation and Testing
Once the resistor was installed and the parameters were adjusted, we performed on-site testing.
The result exceeded expectations:
- Motor speed reduced from 6000 RPM to stop in only 1 second
- No abnormal alarms occurred
- System performance remained stable
- Braking response became smooth and reliable
The customer was extremely satisfied with the outcome.
Why Braking Resistors Matter
When a motor decelerates rapidly, kinetic energy is converted back into electrical energy. If this regenerated energy cannot be dissipated properly, the drive may experience overvoltage faults.
A properly selected braking resistor helps:
- Absorb excess regenerative energy
- Enable faster deceleration times
- Improve machine response speed
- Protect the drive system during high-speed braking
However, resistor selection should not only consider average power, but also instantaneous energy absorption capacity, duty cycle, resistance value, and thermal performance.
Final Thoughts
In automation applications, many problems that seem difficult are often caused by overlooked details in system design.
The right technical diagnosis, combined with proper component selection, can significantly improve machine performance and save customers valuable troubleshooting time.
At our company, we not only provide technical support for industrial automation systems, but also supply original new PLC modules, HMIs, drives, servo systems, and automation spare parts from various brands to support your maintenance and upgrade needs.
