VFD 101 Seminar Takeaways

Top Ten Takeaways

Aaron Osgood, Rockwell Automation Account Manager, recently attended a VFD 101 Seminar at Buckles-Smith Training Center in San Jose, CA. With just over one year of industry experience, Aaron has learned a ton about the electrical industry, specifically industrial automation, power and control. Aaron attended the VFD 101 Seminar and was kind enough to share with us his Top Ten Takeaways.

Buckles-Smith hosts its Industrial Automation 101 classes on a quarterly basis. Upcoming classes can be found on Buckles-Smith’s Online Seminar Schedule. Additionally, upon customer’s requests, Buckles-Smith will host seminars directly at a customer’s site. To schedule a seminar today, please email our Training Coordinator at training@buckles-smith.com.

1. What basics did I learn about motors?
   

• The rotor and the stator are the two main components of an AC induction motor.
• When starting an AC induction motor it is important to remember that the inrush current is roughly 600% of the running amperage.
• The higher the load on the AC induction motor the higher the amperage draw of that motor.

2. What basics did I learn about Variable Frequency Drives?

• Variable Frequency Drives change motor speed by simultaneously altering the frequency and voltage on the motor’s supply side.
• The rectifier, DC Bus and the Inverter are the three main components of a Variable Frequency Drive.

3. How do I calculate the horse power rating for a motor?

4. How do I ensure that system design torque requirements are maintained?

• Design torque is related to the ratio of voltage and frequency, also known as the V/Hz ratio. As long as the V/Hz ratio is maintained, the design torque will stay the same. Typically, the motor’s torque is more important than the horsepower. Keep in mind that the speed between two motors can differ even if the design torque is the same.

5. What are the four primary types of VFD control categories?

• Scalar Control
• Sensorless Vector Control (most common control method!!)
• Flux Vector Control
• Field Oriented Control

• Rockwell Automation has an excellent description of Sensorless Vector Control on page 7 of the AC Drives Using Pulse Width Modulation (PWM) Techniques document.

6. What motor specifications should be referenced when selecting a Variable Frequency Drive?

• Always go by the motor nameplate amperage when specifying a drive. Horsepower is not the best specification to use for picking out the proper drive.

7. What saves more energy during motor operation, a valve or a variable frequency drive?

• Valves can save energy; however, a VFD can save more energy due to its parabolic correlation as opposed the linear correlation associated with a valve.

8. How can you reduce the wear on VFD diodes and capacitors due to voltage spikes and sags?

• Add line reactors!!! Learn just about everything you every wanted to learn about line reactors here: Line Reactors and AC Drives and see our blog about Why you should get a Line Reactor.

9. How can I eliminate, or at least reduce electrical noise?

• Electrical noise should be a concern, but it should not always be an issue. First and foremost proper grounding practices must be implemented to prevent noise issues. Additionally, proper conduit and cabling, such as metal conduit and/or VFD cable, should always be used as well. Rockwell Automation has created an in depth white paper regarding System Design for Control of Electrical Noise.

10. Who serves the best sandwiches in San Jose?

• Panera Bread in Willow Glen! Buckles-Smith always ensures that class attendees walk away with a wealth of knowledge and a full stomach.

Buckles-Smith is an electrical distributor with multiple stocking locations throughout Northern California and the San Francisco Bay Area. Contact us today for any questions you may have and we’ll help you out.