Guide to Selecting a Variable Frequency Drive (VFD) in Industrial and Automation Applications

In this guide, you will learn:

• How to choose the right VFD for your application
• Why motor current is often more important than power (kW)
• Recommended VFD manufacturers
• How to properly size a drive considering start-ups and load condition

What is a Variable Frequency Drive?

A variable frequency drive is an electronic device that adjusts the frequency and voltage supplied to an electric motor, enabling precise speed and torque control. This allows motors to operate more efficiently and adapt to varying load demands.

Key Benefits of Using a VFD

Energy Savings

VFDs can significantly reduce energy consumption. In pump and fan applications, energy savings can reach up to 30%, although actual savings always depend on the specific application, operating conditions, and usage patterns.

Extended Equipment Life

By controlling motor speed and reducing mechanical stress, VFDs extend the life of motors and drive equipment.

Precise Control

VFDs provide accurate speed and torque control, ensuring stable and predictable process performance.

Easy Automation Integration

VFDs can be seamlessly integrated into industrial automation systems for centralized control and monitoring.

How to Choose the Right VFD

When selecting a VFD, consider the following key factors:

Motor Power

Select a VFD based on the motor’s rated power (kW). Choosing an undersized drive may cause overloads, while an oversized drive may not be cost-effective.

Motor Current – Often the Deciding Factor

In many applications, motor current (A) is more critical than rated power. This is particularly true for:

• High-torque applications
• Frequent start-ups
• Pumps, fans, and conveyor systems

How to Check Motor Current

• Read the motor’s nameplate for its rated current. (Link to guide explaining nameplate data)
• Ensure the VFD supports at least the motor’s rated current, ideally with a margin for safety.
• For applications with frequent or rapid starts, consider short-term current peaks to avoid drive overload.

⚠ Technical Tip: For motors with multiple starts per minute or high-torque demands, consider a VFD with overload capability or higher short-term current capacity (heavy-duty rating).

Voltage and Supply Phase

Check whether the motor operates on single-phase or three-phase power, as VFDs support different voltage types.

Application Type

• Pumps: Require smooth starting and energy-saving functionality
• Fans: Benefit from soft start, energy efficiency, and stable airflow or pressure control
• Conveyors: Require precise speed and torque regulation

IP Protection

VFDs are available with various Ingress Protection (IP) ratings (IP00, IP20, IP55, IP66, etc.), which is important depending on industrial conditions such as dust, humidity, or harsh production environments. For more information, see our IP Protection Guide.

Additional Options and Communication

VFDs offer multiple communication protocols such as Modbus, Profinet, Profibus, EtherNet/IP, and others. Optional modules, expansion cards, and additional features allow for device customization to meet specific application requirements. (link to additional equipment)

Recommended VFD Manufacturers

LS Electric – Drives suitable for a wide range of applications. (View Offer)

INVT – Flexible drives with IP55 protection up to 110 kW, supporting modern BLDC and PM motors. (View Offer)

Parker – High-performance drives for demanding and dynamic industrial applications. (View Offer)

Common Applications of VFDs

• Industrial automation
• Pumps and pumping systems
• HVAC systems and fans
• Compressors
• Conveyor systems
• Production lines
• Machinery

Advantages of Using a VFD

• Energy efficiency: Up to 30% lower electricity consumption
• Longer equipment life: Reduced mechanical wear
• Precise control: Stable speed and torque regulation
• Seamless integration: Easy connection to automation systems
• Reliable operation: Handles frequent or heavy-duty start-ups

Frequently Asked Questions (FAQ)

What is a variable frequency drive?

A VFD is an electronic device that allows speed control of electric motors by adjusting the supplied frequency and voltage.

Do VFDs reduce energy consumption?

Yes. By running the motor only at the required speed, energy consumption can be significantly reduced, achieving up to 30% savings for pumps and fans.

How do I choose the right drive based on power and current?

Consider the motor’s rated power, current, supply voltage, and application. The VFD should support at least the rated motor current, with additional margin for heavy-duty applications.

Does GO TO d.o.o. provide installation support?

Yes. We offer professional consulting, technical support, and integration of VFDs into industrial systems.

How can I contact GO TO d.o.o. for further information or a quote?

For questions, consultations, or a quote, you can contact us here. Our experts will help you select and integrate the ideal VFD solution for your application.