What Are Variable Frequency Drives?

Variable frequency drives (VFDs) are devices that control the voltage and frequency that’s being supplied to a motor; they, therefore, control the speed of the motor and the system its driving. By meeting the process demands, the system efficiency can be improved. Variable frequency drives are also commonly known as AC drives, frequency drives, inverters speed drives, and micro-drives. A VFD provides continuous range of speed control and is capable of adjusting the speed and torque of an induction motor. A VFD can offer a number of solutions depending on the required application. Some benefits include energy savings on fan and pump application, protections from overload currents, as well as better process control and regulation.

Classification of Variable Frequency Drives

Variable frequency drives, or VFDs, can save you money on your commercial building energy costs in Toronto. There are a few different types of AC drives that have various functions, including:

Mechanical Speed Control

Fixed speed motors can be controlled with a mechanical speed control device when needed. Examples of mechanical speed control include fluid coupling, magnetic speed control, and mechanical transmissions like belt drive and gear boxes. The efficiency of this option depends on a number of factors, although most typically have low efficiencies at low loads.

Advanced Motors

These are generally classified as a group that require power electronics and microprocessor controls for operation. All advanced motors allow for variable speed operation and are now practical with today’s electronics. Advanced motors are starting to be employed in original equipment manufacturer applications, and have become available as general purpose motors with ratings up to 600 HP.

Tips and Cautions for Using Variable Frequency Drives

A VFD is an extremely cost-effective choice if the duty cycle is more evenly distributed over the entire range of flow rates. Energy savings can even improve if the performance and system resistance curves are steep. However, despite its cost-saving ability, many good VFD applications are overlooked—mainly because process control and reliability outweigh the benefits of efficiency. VFD savings can be significantly greater for variable torque loads since the horsepower varies proportionally to the cube of the speed. Installation costs for drives above 25 HP can be comparable to the total cost for the drive while installation costs can end up being more than the cost of the drive below 25 HP.

If you’re looking to have a VFD for your commercial property, there’s no better choice than PL Energy Services. Just last year, we secured government funding for the implementation of a variable frequency drive on a 20 HP Makeup Air Unit. This provided energy savings up to 55%, saving our client thousands of dollars a year. We can do this for your commercial business too—we’re one of the top-rated HVAC testing and balancing companies in the GTA, and we would be more than happy to help you save on your energy bill. Contact us today to learn more about variable frequency drives and how they can help save you money.