Things You Must Know about VFD

Things You Must Know about VFD

The use of motors and controlling devices is nothing new. Engineering and technology have come a long way, and there have been some amazing new inventions that have made our work easier and smoother.

One such innovation that has benefitted humankind is the VFD. A variable frequency drive or a VFD is a device that effectively combats the limitations of AC powers.

Alternate current or AC motors operate based on the incoming power and the number of poles inside the machine. This means anytime you need to alter the speed of the motor, you have to either adjust the incoming power or switch the number of poles inside the engine, both of which are not workable solutions. Transistor systems are available, but they are pretty complex to operate. And this is where a VFD is applicable, which lets you immediately and effectively change the motor settings.

This article aims to discuss how VFDs work and where you can buy the best quality VFDs in India.

How does VFD change the frequency?

The use of VFD is to change the frequency of the power to an AC motor when the input supply remains constant. But how does it do that?

The primary function of VFD is to adjust the AC power according to the motor requirement. It works by taking in the AC power and then converting it to DC power with the help of a rectifier. VFD further filters the DC power by passing it through a DC bus. This power passes through an inverter converting into DC pulses that functions like AC power. Since DC power is easier to adjust and control, VFD changes the AC to DC, giving you more control over the current input into the motor you are using.

What is carrier frequency in VFD?

When buying a VFD, you will come across a term – carrier frequency. Let us discuss and find out what this term means.

The frequency at which the VFD output transistors are switched is called the carrier frequency. Also known as changing frequency, the carrier frequency of VFDs typically ranges from 4khz to 16khz. To explain it more simply, the rate at which the DC bus voltage is switched on and off by Insulated Gate Bipolar Transistors (IGBT) during pulse width modulation (PWM) is known as the carrier or switching frequency.

How to select VFD drive for motor

When it comes to finding the best VFD for your motor, a lot needs to be considered. You cannot just buy any VFD available in the market. Since if the VFD is not compatible with your motor, it will not work as well. The kind of VFD you need would primarily depend on the application and the system of the engine you will be using it with.

Do note that VFDs can be used for multiple purposes. Primarily utilized for controlling the speed of AC motors in devices like fans and pumps, VFDs, when sized correctly, can also come in handy as a phase converter when using multiple-phase engines running on a single-phase power supply. Hence to select the suitable VFD for your motor, you need first to consider the use and the type of load being applied to the engine. The other things you need to look at before buying a VFD are:

  • Static speed accuracy
  • Requirements for starting torque
  • Type of controlled objects
  • Speed regulation range

To understand the above requirements when getting a VFD for your motor, it would be best if you could get as much information as possible on the engine you will be using the VFD for. The data you can collect from the motor nameplate is as follows:

  1. Total load amps (FLA)
  2. Horsepower
  3. Service factor
  4. Voltage
  5. RPM

Once you know these things, you can choose the suitable VFD that will enhance the workings of your motor.

What is the difference between a VSD and a VFD?

When looking for VFDs, you might have come across another similar term, VSD. While the names might seem similar, don’t confuse between the two. While VFD stands for variable frequency drive, VSD is the short form for variable speed drive.

There are many differences between the two devices – VFDs and VSDs. However, the main difference between the two is how they function. VFDs help control the speed of an AC motor by converting the AC power supply to DC and allowing you to adjust the frequency of the AC power to the motor. Whereas VSDs aid in varying the speed of a DC motor by letting you alter the input voltage to the engine.

Buy the best VFDs at Schneider Electric eShop.

Different kinds of VFDs can be found and bought from the Schneider Electric eShop at highly affordable prices. You can browse the website from the comforts of your home and buy a VFD that is most suited for your motor requirements. Schneider Electric eShop is a one-stop, trusted, and authentic destination for all your electrical needs.

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