Can Variable Frequency Drives Increase Torque?

Variable Frequency Drives (VFDs) are often used in industrial and commercial applications to control the speed of electrical motors. One common question that arises is whether these drives can increase torque. This article delves into the capabilities and limitations of VFDs in terms of torque enhancement, providing insights and practical tips for their effective use.

Understanding Variable Frequency Drives (VFDs)

Variable Frequency Drives (VFDs) are electronic devices that are used to control the speed of AC motors by varying the frequency of the electrical power supplied to the motor. By controlling the input voltage and frequency, VFDs can achieve precise control of motor speed, ensuring that the motor operates at the optimal speed required for the specific application.

Can VFDs Increase Torque?

Yes, VFDs can increase torque, but not indefinitely. Torque is the rotational force that causes a stationary object to rotate. In industrial applications, increasing torque can be crucial for overcoming starting and overcoming starting resistance in motors.

Break-Away Torque

One of the key capabilities of VFDs is their ability to provide additional torque, known as break-away torque, during the initial start-up phases of a motor. By increasing the voltage and frequency at lower frequencies, VFDs can provide a brief, extra boost of torque to help the motor overcome initial resistance and start moving.

Operational Limitations

It is important to note that using break-away torque continuously is not recommended. The reason for this is that excessive use can lead to overheating of the motor components, which can reduce the lifespan of the drive and motor. Continuous heavy-duty operation could also exceed the rated capacity of the VFD, potentially leading to burnout or damage.

Therefore, while VFDs can provide a significant boost of torque to help motors start up and overcome initial resistance, it is essential to limit their use to intermittent periods. For critical applications where continuous torque boost is required, other solutions such as solid-state starters or converters might be more appropriate.

Practical Applications

One common application where VFDs effectively increase torque is in aggregate conveyor systems. Aggregate conveyors are subject to significant loads and resistance during the start-up phase, which makes them ideal candidates for VFDs. By using VFDs, the conveyor can achieve a smoother start-up process, reducing stress on the system and improving overall efficiency.

Start-Up Best Practices

For aggregate conveyor systems, it is recommended to start the motor using a VFD only once every 10 minutes or as specified by the manufacturer. This approach not only extends the lifespan of the VFD and motor but also ensures that the system operates at peak efficiency. Overusing the torque boost can lead to unnecessary wear and tear, reducing the reliability and longevity of the equipment.

Conclusion

In summary, VFDs can be effectively used to increase torque, particularly during the start-up phase of a motor or conveyor system. However, it is crucial to understand the operational limits and limitations of VFDs to ensure their proper and safe use. By adhering to best practices and implementing effective maintenance routines, you can maximize the benefits of VFDs while maintaining the integrity and longevity of your systems.

Keywords: Variable Frequency Drives, Torque Increase, Electrical Motors