Design World

  • Home
  • Technologies
    • ELECTRONICS • ELECTRICAL
    • Fastening • joining
    • FLUID POWER
    • LINEAR MOTION
    • MOTION CONTROL
    • SENSORS
    • TEST & MEASUREMENT
    • Factory automation
    • Warehouse automation
    • DIGITAL TRANSFORMATION
  • Learn
    • Tech Toolboxes
    • Learning center
    • eBooks • Tech Tips
    • Podcasts
    • Videos
    • Webinars • general engineering
    • Webinars • Automated warehousing
    • Voices
  • LEAP Awards
  • 2025 Leadership
    • 2024 Winners
    • 2023 Winners
    • 2022 Winners
    • 2021 Winners
  • Design Guides
  • Resources
    • Subscribe
    • 3D Cad Models
      • PARTsolutions
      • TraceParts
    • Digital Issues
      • Design World
      • EE World
    • Educational Assets
    • Engineering diversity
    • Trends
  • Supplier Listings
  • Advertise
  • Subscribe

Time, Control and Cost Efficiency

By Steve Meyer | June 10, 2012

In motion control, more so than any other discipline in the field of control, time is the most critical value to understand.  There is an incredible amount of information hidden in what is probably the most obvious and yet, least questioned aspect of motion and motor control.  How much time do we have to make the motion happen?

Even in motor applications that do not appear to have any “control” to speak of.  Just turn on your air conditioning compressor or fan motor.  What happens next is kind of amazing.  The motor gets power and attempts to catch up to line speed, 1800 RPM, instantly in one cycle of AC power.  At 60 hertz, there are 16.6 milliseconds to a sine wave.  That’s not a lot of time to accelerate from standing still, to full speed.  So a lot of current goes into the motor to overcome the inertia of the rotor and load.  Typically 3.5 to 5 or 6 seconds later, the motor is at speed.

If there are 50,000,000 air conditioners in the US and they cycle 10 times an hour during an 8 hour period in the summer, then 4.4 million hours of load are generated, and that load is not doing any cooling.  If the fan load is 3/4 HP, then there are 2.4 million kWh of power that are being used just to start stuff up.  That’s a lot of power.

It would be nice to be able to “soft start” the small loads over 10 seconds.  Conventional control theory says you need the control loop to close 10 times faster than the event you are trying to control.  That means that the control loop would have to run 1.6 milleseconds to get the inrush current measured.  The transistors require even faster control loops to keep the current under control.

So it becomes more difficult than we imagine to get the smaller loads under control.  And more expensive.  That seems to be the barrier.  We are now able to buy small inverters in the $100. price range.  We have to evaluate the payback potential.  If I have a 1HP load running 8 hours a day, that’s 6kWhr a day of power.  If I can cut the power usage by half, I can save 3kWhr/day or about 33 cents in many states in the US.

That looks like $120.45 the first year!  That’s a pretty good deal.  Unfortunately, it is based on a very optimistic scenario.  But not something we should ignore.  As aging coal fired power plants begin to be “retired” due to aging, the easiest way to make up power shortages is to reduce demand.  This may be a leading force in the effort to make more efficient motor technology.  And as control technology costs continue to decline, some opportunities would appear to increase.

 

Mechatronic Tips

You Might Also Like


Filed Under: Mechatronic Tips

 

LEARNING CENTER

Design World Learning Center
“dw
EXPAND YOUR KNOWLEDGE AND STAY CONNECTED
Get the latest info on technologies, tools and strategies for Design Engineering Professionals.
Motor University

Design World Digital Edition

cover

Browse the most current issue of Design World and back issues in an easy to use high quality format. Clip, share and download with the leading design engineering magazine today.

EDABoard the Forum for Electronics

Top global problem solving EE forum covering Microcontrollers, DSP, Networking, Analog and Digital Design, RF, Power Electronics, PCB Routing and much more

EDABoard: Forum for electronics

Sponsored Content

  • Widening the scope for machine tool designers with FORTiS™ enclosed encoder
  • Sustainability, Innovation and Safety, Central to Our Approach
  • Why off-highway is the sweet spot for AC electrification technology
  • Looking to 2025: Past Success Guides Future Achievements
  • North American Companies Seek Stronger Ties with Italian OEMs
  • Adapt and Evolve
View More >>
Engineering Exchange

The Engineering Exchange is a global educational networking community for engineers.

Connect, share, and learn today »

Design World
  • About us
  • Contact
  • Manage your Design World Subscription
  • Subscribe
  • Design World Digital Network
  • Control Engineering
  • Consulting-Specifying Engineer
  • Plant Engineering
  • Engineering White Papers
  • Leap Awards

Copyright © 2025 WTWH Media LLC. All Rights Reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media
Privacy Policy | Advertising | About Us

Search Design World

  • Home
  • Technologies
    • ELECTRONICS • ELECTRICAL
    • Fastening • joining
    • FLUID POWER
    • LINEAR MOTION
    • MOTION CONTROL
    • SENSORS
    • TEST & MEASUREMENT
    • Factory automation
    • Warehouse automation
    • DIGITAL TRANSFORMATION
  • Learn
    • Tech Toolboxes
    • Learning center
    • eBooks • Tech Tips
    • Podcasts
    • Videos
    • Webinars • general engineering
    • Webinars • Automated warehousing
    • Voices
  • LEAP Awards
  • 2025 Leadership
    • 2024 Winners
    • 2023 Winners
    • 2022 Winners
    • 2021 Winners
  • Design Guides
  • Resources
    • Subscribe
    • 3D Cad Models
      • PARTsolutions
      • TraceParts
    • Digital Issues
      • Design World
      • EE World
    • Educational Assets
    • Engineering diversity
    • Trends
  • Supplier Listings
  • Advertise
  • Subscribe
We use cookies to personalize content and ads, to provide social media features, and to analyze our traffic. We share information about your use of our site with our social media, advertising, and analytics partners who may combine it with other information you’ve provided to them or that they’ve collected from your use of their services. You consent to our cookies if you continue to use this website.