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What is a VFD?

A Variable Frequency Drive (also known as VFD, AC Drive, or Inverter) is a controller that runs and monitors your pump’s motor. The primary feature is its ability to control the speed of the pump by adjusting the frequency of the motor’s electrical current. A VFD can regulate the rotational speed of the motor by modifying the frequency, which in turn alters the flow rate and pressure of the pump. 


Advantages of a VFD

Decreases mechanical strain

Traditional pump systems typically experience high-stress conditions during startup and shutdown, which can significantly reduce the lifespan of the pump. A VFD controls and optimizes the acceleration and deceleration rates, reducing mechanical strain and extending the pump's life.

Energy efficient

Rather than running at full capacity 100% of the time, a VFD adjusts your motor speed to closely match output requirements. This can lead to energy savings from 10-50%!

Improved protection

VFDs commonly incorporate protective features that enhance the safety of the pump system. For example, the VFD monitors the current flowing through the motor and can detect overcurrent conditions. In the event of an overload or electrical fault, the VFD activates overload protection and will shut down the pump. This prevents damage to the motor and other system requirements.

Troubleshooting assistance

VFDs frequently measure things like voltage, power factor, and motor current (amp draw). Users are able to keep an eye on the pump's performance and spot any potential problems as a result.

Adding a VFD into a pump system has numerous benefits: it allows for precise control of the pump's speed which then optimizes the flow rate and pressure based on demand. The VFD’s ability to control the acceleration and deceleration of the pump extends its lifespan in turn. Reduced energy consumption due to its energy saving features... and more!


VFD Types


The i550 VFD is a frequency inverter manufactured by Lenze, designed to control the speed of electric motors. Here are the key features and functionalities of the i550 VFD.

Power Range

The i550 VFD is available in power ranges from ½ HP (horsepower) to 20 HP, allowing it to handle many different applications.
IP66 Washdown Protection

Its IP66 protection is hose-proof and dust-tight making it ideal for harsh and wet environments.

Impact-Resistant Case (NEMA 4X)

The VFD comes in an impact-resistant case with a NEMA 4X rating making it suitable for both indoor and outdoor applications.

IO-Link Device Interface

The i550 VFD is the first decentral drive in the market with an IO-Link Device Interface, which is available as a special order option. IO-Link is a communication protocol that automation systems use to link sensors and actuators.


  • Preserved Presettings

  • Remote Adjustable Switching Points

  • Real Time Data & Diagnosis

Vector Control Without Sensors

Sensorless vector control allows users to operate synchronous motors without requiring feedback from external sensors.

Simple User Interface

The VFD has an easy-to-use user interface that allows for quick setup and navigation through parameter settings.

Onboard Display

The VFD has an onboard display that monitors its performance and status. Also, a Micro USB interface is available for programming and diagnostics.

Multiple Inputs and Outputs

Several digital and analog inputs are included which you can use to connect remote controls, safety interlocks, and more.

Full PID Programming

The VFD supports full onboard PID (Proportional-Integral-Derivative) programming, enabling it to interface with flow meters, level controls, pressure sensors, can/bottle fillers, and other control systems.

Optional Front-Mounted Potentiometer

It can be ordered with an optional front-mounted potentiometer, which acts as a speed control knob.

Fieldbus Communications

The VFD can be configured with various Fieldbus communication options, including CANopen, Modbus RTU, I/O-Link, EtherCAT, EtherNet/IP, and Modbus TCP.

Ecodesign Standard Compliance

The i550 VFD meets the requirements of the Ecodesign standard EN 50598-2, ensuring its environmental sustainability and energy efficiency.

Light Duty Load Characteristic

The VFD's "Light Duty" load characteristic allows for a higher output current, considering overload capacity, ambient temperature, and switching frequency.

Functional Safety (STO)

The Safe Torque Off (STO) ensures safety during motor shutdown and prevents unintended motor movements.

SMART Keypad App

Lenze offers the SMART Keypad App for Android or iOS, enabling users to diagnose and parameterize the VFD wirelessly using a WLAN module.


AC Tech

The Lenze AC Tech SMVector series variable frequency drive (VFD) is a type of motor controller used to control the speed and torque of electric motors in various industrial applications. It is designed to offer a wide range of features for efficient and precise motor control.

Power Range

The SMVector VFD can be used with either a 208/240 VAC single-phase or 3-phase power supply.


The VFD comes in a convection-cooled NEMA-4X/IP-65 indoor enclosure that provides protection against dust, moisture, and water jets. This makes the VFD suitable for outdoor use and allows for decentralized wall mounting.

Programmable I/O

The VFD features programmable digital and analog Input/Output (I/O) options. This allows the VFD to be set up for multiple preset speeds, electronic braking, motor jogging, and more.

EPM Memory Technology

The SMVector drive uses EPM memory technology, which is a rugged memory chip that plugs directly into the VFD's fascia. This allows the user the ability to directly copy the VFD's parameters onto the chip, ensuring that the VFD is ready to use without the need for powering up.

Flux Vector Operation

The VFD uses flux vector operation, which allows for precise motor control.

On-Board PID Controller

The VFD includes an on-board PID controller with an energy-saving "Sleep Mode" function, which helps regulate processes efficiently.

EMC Filter

It comes with a built-in EMC filter (standard on 240 V 1Ø, optional on 400 V/480 V 3Ø), ensuring compliance with electromagnetic compatibility standards.


The VFD supports various communication protocols, including CANopen, DeviceNet, EtherNet/IP, LECOM, Modbus RTU, and PROFIBUS.

Motor Control

This VFD includes auxiliary ramp to stop, motor thermal overload protection, dual acceleration/deceleration rates, preset speeds, DC injection braking, and other motor control features.

Dynamic Braking

Packaged dynamic brake option includes control and resistors in an easy to implement solution for fast stopping or deceleration requirements.



The KBDA Variable Frequency Drive (VFD) is an electronic device used to control the speed and torque of an electric motor by varying the frequency and voltage supplied to the motor.

Power Range 

The KBDA VFD is available in eight different models, ranging from 1 to 3 Horsepower (HP). These models are designed to accommodate motors of different power ratings.


The casing of the KBDA VFD is made of rugged die-cast aluminum, which provides durability and protection. It is NEMA 4X approved, making it suitable for wet locations both indoors and outdoors. The IP-65 rating ensures protection against dust and water.

Flux Vector Control Without Sensors

The Flux vector control allows for precise motor speed and torque control.

Electronic Inrush Current Limit (EICL™) Protection

During power-up, this protection mechanism prevents harmful inrush AC line current, reducing stress on the motor and power supply.

Run/Fault Relay Output Contacts

These contacts can be used to turn equipment on or off, signal warnings, or indicate faults that have occurred during operation.

Jog-Local Remote

This feature allows users to set the drive to Jog Mode or switch between local (keypad) and remote operation modes.

Holding Torque at Zero Speed

In "Stop" mode, the VFD resists motor shaft rotation, preventing the motor from free-wheeling when stopped.


The VFD is designed to shut down if the AC line input voltage goes above or below the operating range. This eliminates tripping caused by high bus voltage resulting from rapid deceleration of high inertial loads. It also has a built-in mechanism to protect the motor by shutting down if a short circuit occurs at the motor's terminals (phase-to-phase).


This feature ensures smooth recovery to the previous set speed during momentary power losses.

IODA Input/Output Multi-Function Board 

This optional board includes preset frequency, up/down frequency control, signal isolation, isolated output voltage for controlling auxiliary devices, open collector outputs, and output relay contacts.

Modbus Serial Communication Module 

Allows direct communication between drive and Modbus2 protocol.

Class “A” (CE) RFI Filter

Provides RFI suppression to reduce electromagnetic interference.

Pulse Width Modulated (PWM) output

The sine wave coded PWM output provides high motor efficiency and low noise. Adjustable Linear Acceleration and Deceleration make the drive suitable for soft-start applications.



VFD maintenance entails a number of practices to keep them safe from external factors and prevent mechanical faults. The following are the most important VFD maintenance practices:


Visual Inspections

Regular visual inspections are required to monitor any changes in the VFD's environment. This includes recording temperature and humidity levels, VDC (Voltage Direct Current) bus voltage, output voltage, current, and frequency.

Regular Cleanings

VFDs are typically classified as NEMA 1, NEMA 4, or NEMA 12. NEMA 1 VFDs are intended for indoor use and have side vents to improve airflow. While these vents provide some protection against solid foreign objects, dust can accumulate inside the unit as well as on the vents themselves. Regular cleaning is required to prevent the accumulation of materials that could obstruct airflow or compromise the performance of the VFD. It is important to note that cleaning VFDs with solvents or water-based cleaning tools may damage the sensitive electronic components.

Connection Checks

Although the VFD unit itself may not be moved frequently, connections can loosen over time due to mechanical vibrations, heat cycles, or other incidental movements. Regular inspections of the connections are necessary to identify and rectify any loose connections. It's critical not to overtighten or re-torque the connection screws, as this can cause problems similar to loose connections.

Parts Replacement

Certain components of the VFD require periodic replacement to maintain its performance and reliability. The replacement schedule for some key components is as follows:

  • Filters: Filters should be cleaned on a monthly basis and replaced annually. Clean filters help keep dust and debris out of the VFD's internal components.

  • Cooling Fans: The cooling fans of the VFD need to be replaced every three to five years. Properly functioning cooling fans are essential to dissipate heat and prevent the VFD from overheating.

  • Main Bus Capacitors: The main bus capacitors should be replaced every seven years.

VFDs can be kept in good working order while lowering the risk of malfunction by following these maintenance practices.



Each type of VFD has its benefits, this allows users to choose the one that best meets their requirements.

The i550 VFD stands out due to its broader power range, versatile enclosure, efficient sensorless vector control, intuitive user interface, and the inclusion of the SMART Keypad App.

The Lenze AC Tech SMVector VFD stands out for those requiring outdoor use and advanced motor control capabilities. This VFD also has a more versatile power supply compatibility, on-board PID controller, and electromagnetic (EMC) compatibility features.

The KBDA VFD stands out for its wide range of power models, rugged enclosure, optional direct Modbus communication, precise sensorless flux vector control, comprehensive protection features, diverse frequency control functions, and PWM output.

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