Variable Frequency Drives (Video On Demand)
In Variable Frequency Drives, you'll learn ...
- What variable frequency drives (VFDs) are and what they do
- How VFDs can save on operating and maintenance costs
- Historical developments and advancements of VFDs and their relevance
- Applications of VFDs in pumps, conveyors, process lines, etc.
Since the mid-1980s, solid state electronic devices have been used to make motor controllers with 60 cycle-per-second input power and variable voltage, variable frequency output. As with many new devices, there have been some reliability problems, but the technology has gotten better, so that variable frequency drives (VFDs) are now used in many places where DC speed control was once, almost exclusively, the means of motor speed control. Today’s devices not only eliminate most of the harmonics on the input side of the motor controllers, but they also make the power factor very close to unity, greatly increasing the efficiency of most modern devices.
This webinar explains the different ways to control the speed of alternating current (AC) motors. By their very nature, most AC motors are not easily speed controlled. But we will review some of the historical developments and advancements that have been made with VFDs and see how engineers have done things that were once deemed impossible. Some of the important lessons in this webinar include demonstrations and explanations for how VFDs convert 60 Hertz constant voltage power to variable voltage, variable frequency power; how a single phase voltage can be turned into a three phase voltage to run single phase motors; and how current harmonics cause voltage harmonics to appear.
Special Note: Course E-2057, E-3014, and webinar E-2014W are alternate presentations of the same course material. Therefore, only one version, either the course or webinar, can be taken during a renewal cycle. If you have any questions regarding course eligibility, please contact our Customer Service Team.
Specific Knowledge or Skill Obtained
This course teaches the following specific knowledge and skills:
- A brief history of variable speed drives and the reasons that variable speed motors are useful
- How VFDs convert 60 Hertz constant voltage power to variable voltage, variable frequency power
- The block diagram of VFDs and how the various blocks work
- Why voltage must vary as frequency varies
- How a single phase voltage can be turned into a three phase voltage to run single phase motors
- Some of the latest developments in VFD technology relative to harmonics and power factor
- Other uses of inverters, including uninterrupted power supplies
- Applications where VFDs are effective
- High voltage, high power applications and how these can be achieved
Video on Demand
This course is a recorded version of a live lecture and will be streamed directly to your computer's media player. Our format is generally compatible with media players included with all computers and mobile devices. After watching the video presentation, you will return to your PDHengineer log in account to take the online quiz. While this is a recording of a live presentation, please note that this recording will not qualify as a "live" or "interactive" continuing education activity in those states where it is required.
Certificate of Completion
You will be able to immediately print a certificate of completion after passing a multiple-choice quiz consisting of 10 questions. PDH credits are not awarded until the course is completed and quiz is passed.
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