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Q. What is a Variable Frequency Drive?

A. A variable frequency drive is an electronic device that allows you start, stop and control the speed of a three phase motor. It is also a motor starter as it is equipped with overload protection.

Q. Will a variable frequency drive work with 220 volt single phase power?

A. Yes, a variable frequency drive will convert 220 single phase power to 220 volt three power which will afford you all the features of its intended use. However, make sure to select a drive that is advertised to do so, not all drives handle the phase conversion as well as others.

Q. Is this device available in 115 volt single phase input and 220 volt three phase output?

A. Yes, we have drives in stock up to 7.5 HP with 115 volt single phase input and 220 volt three phase output.

Q. Can a variable frequency drive be used on a single phase motor?

A. No, their intended use is for three phase motors.

Q. Will using a variable frequency drive use more or less current?

A. The variable frequency drive has a soft start feature. This feature allows you to gently ramp the motor up to your desired speed. This will reduce the inrush current also reducing your electrical consumption. The soft start feature will also reduce the wear and tear on your driven piece of equipment.

Q. Can the existing switches on my piece of equipment be used with a variable frequency drive?

A. Yes, however, you will have to rewire those switches to a terminal strip on the drive and program the drive for remote start / stop.

Q. What are some of the differences between models from the same manufacturer with the same HP rating?

A. The most basic drives are for general or light duty. They are typically smaller in size and generally need to be installed in an enclosure, as they are open at the top or bottom where your leads come in and go out.

If you want a drive that can be mounted on the wall or on your equipment, look for one that is in a NEMA 1 enclosure.

If the drive is being operated in a very dusty environment, look for one in a NEMA 12 enclosure, which is gasketed and dust tight.

If the drive is being operated in a wet or moist environment, look for one in a NEMA 4 enclosure, which is gasketed and waterproof.

If your application is more demanding, select one that has a sensorless vector feature. This feature will provide you a greater amount of torque at lower speeds.

Q. Do I need to buy a drive with a higher HP rating than my motor?

A. No, variable frequency drives are based on the amount of current the motor will draw. However, some applications such as punch presses or others that use a fly wheel should be upsized.

Q. Do I need a special VFD rated motor?

A. If you already have a motor use it, you can always change it later. Most motors manufactured today are rated for use with a VFD. Some models will allow you a greater range of speed than others. You can always contact us to help with your selection.

Q. Will I be able to reverse the motor rotation?

A. Yes, some models have a forward/reverse button on the keypad. Otherwise, you can remote forward/reverse the motor with a remote switch.


Variable frequency drives now play an important part in major industry. Within the last 10 years they have been perfected to control and vary the speed of 3 phase electric motors. You may have heard them referred to as adjustable frequency drives, VFDs, and/or inverters.

They serve many purposes, besides speed control. If you are a homeowner or hobbyist who purchased a lathe or milling machine with a 3 phase electric motor you are faced with a dilemma. You probably don’t have 3 phase power to operate it. Before variable frequency drives you had to purchase a rotary phase converter. That would effectively convert your single phase power to 3 phase power. Rotary phase converters are noisy and are not the ideal item you would want in your basement. Today these solid state variable frequency drives convert single phase power to 3 phase power silently and efficiently. They are available in 115 volts or 230 volts single phase input.

Variable frequency drives have also played a major part in the growth of industry. They are known for reducing the consumption of electrical power. Many utility companies have offered and are still offering significant rebates when purchasing these items. They reduce the inrush current and have lowered the demand for more power. These drives have also been improved and are available in sensorless vector models. These allow significant torque control, especially at lower speeds.

Many options are available for variable frequency drives. Dynamic braking as well as remote keypads are 2 of the most popular requests. When selecting a drive it is important to mention the application. They are available in constant torque or variable torque models.

From home use to industrial use, variable frequency drives are actively used. In industry irrigation pumps as well as rock crushers are just 2 of the many areas of use. Home workshops have been set up in garages and basements throughout this country with the use of these drives.