WHAT IS VFD?

In this article we will learn ….

What is VFD?

Use of VFD in manufacturing world.

Advantages of VFD?

VFD stands for “Variable Frequency Drive”.

It is an electronic device designed to control the speed of a motor by varying the frequency and voltage supplied to the motor. It is mainly used to drive Induction Motors and is commonly referred to as AC drives or Inverters.

VFD’s main task is to change the power supply frequency in order to adjust the speed of the motor.

The supply voltage and frequency supplied to the VFD are fixed (typically ranging from 50 Hz to 60 Hz). The VFD then smoothly varies the frequency to adjust the motor’s speed.


Rotational Speed of Motor is calculated with following formula.

Rotational Speed of =          120* Supply Frequency [Hz]     * (1-S) [rotation/min]
Motor                                No of Poles                          
  1. When motor is stopped S is 1.
  2. No. of Poles depend on Motor configuration-4p means 4 pole motor.
  3. S=Slip-During rated speed S is 0.03 or 0.05.

Application in Manufacturing Industries

1.Damper Control

  • Airflow speed of the motor is controlled using a Variable Frequency Drive (VFD).

2.Screw Conveyor

  • In this Screw Conveyor application, a VFD is used to control the flow of material in the hopper.
  • Adjusting the speed of the motor controls the flow of material.

3.Conveyor Application

Nowadays, VFDs are mostly used in Conveyor Applications.

  • For Bottle filling applications, conveyors are used to transfer bottles. To ensure a smooth start and stop of the conveyor, an inverter is used here.
  • They are also used to improve operating efficiency by adjusting the speed as required.
  • There are thousands of applications where VFDs are used, ranging from handling small machines to managing the processes of large plants.
Categories PLC

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