MD_Motors Monthly_: Thermal Safety Margins for Servomotors

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June 29, 2010

Legislation introduced in the senate sets up a Crush for Credit program that would give a $25/hp federal rebate to replace inefficient motors with ones rated as NEMA Premium energy-efficient. It also provides for a $5/hp rebate for the proper disposal of less efficient motors that one can assume means recycling the materials of the older motor. The legislation was proposed by Sen. Blanche Lincoln (D-AR) as S.3436. The proposed funding of the program was capped at $700 million. We’ll keep you informed as this legislation works its way through Congress.

Of course, you should be working your way through the questions in our World’s Smartest Design Engineer contest. Our May winner of a $250 Amazon gift card was Steven Ho, aka chemicalengineer in the game. So far, all of our players have answered over 350,000 questions covering eight subject categories. Interestingly, one of our most popular categories also appears to be one of the most challenging: Mechanical Engineering. It shares its popularity rating with All Things Energy and its difficulty rating with Hydraulics & Pneumatics. The monthly competition begins anew on July 1, with the July prize to be a $250 gift card from Dick's Sporting Goods!

-- Bob Repas, Assoc. Editor

In this issue of Electric Motors Monthly:

Thermal Safety Margins for Servomotors
Cyclemotor Kit Turns Any Bike into an Electric Moped
E-Stop and Go: Safely
Game, Set, Match for Centre Court’s Electromechanical Actuators
Technology, Professionalism First in Robotics Competition
Video: Motor drive vibration suppression
New Products

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Articles

Thermal Safety Margins for Servomotors

Motion-system designers frequently crank pretty hard on servomotors. To get the highest possible performance, they’ll often command the servomotor to put out the maximum peak torque that its maker allows. However, servomotor electrical windings can overheat rapidly and even burn up when this happens. Consequently, a servomotor needs a hot-spot temperature safety margin.

Cyclemotor Kit from Neodymics Turns Any Bike into an Electric Moped

The Cyclemotor kit from Neodymics, Madison, Wis. (www.neodymics.com), can turn any standard 26 or 27-in. bicycle into a 1-hp moped that can cruise at up to 28 mph. The one-piece kit contains all that is needed for the conversion, including batteries, brushless-hub motor, transmission, drive electronics, controls, and a shock absorber and simple suspension. All the components are assembled into a single 40-lb unit that attaches via three quick-release latches to the front fork of the bike, replacing the front wheel with a 16-in. powered wheel. Most of the 40 lb are mounted low, so the center of gravity, along with handling and stability, improves.

E-Stop and Go: Safely

Emergency-stop switches, generally referred to as E-Stops, help ensure the safety of people and machinery by delivering a consistent and predictable fail-safe response. A wide range of electrical machinery need these specialized switches to meet workplace safety and established international and domestic regulatory requirements. E-Stops differ from simple stop switches that merely turn equipment off in that they offer foolproof equipment shutdown.

Game, Set, Match for Centre Court’s Electromechanical Actuators

Wimbledon’s retractable roof now consists of two sections opening north and south. A total of 10 trusses in the two sections span 77 m (253 ft) over Centre Court and support 1,586 m2 (17,060 ft2) of fabric. A wheeled carriage or “bogie” at each end of the 110-tonne (121-ton) trusses rolls along two sets of parallel rails to move the roof section. Overall, 40 bogie motors, two on each of the wheeled carriages, position the roof trusses. Overall, the retractable roof has 148 axes of control using 20 real-time Moog servo controllers and 20 PLCs housed in 40 control cabinets.

Technology, Professionalism First in Robotics Competition

Robots taking over the Georgia Dome in a battle for world domination? It’s not a summer blockbuster; it’s the FIRST Robotics Competition Championship. This year’s competition in Atlanta, April 15 to 17, was the culmination of a three-month season for more than 45,000 students from 12 countries. Starting in January, student teams designed and built robots that would compete both with and against other teams’ robots for top honors.

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Using Current Sensors in Motor Drives, Power Inverters
Avago Technologies
DATE: July 7th, 2010
TIME: 12:00pm ET/9am PT

Learn about Avago's solution for sensing motor current and transmit signals from high voltage motor phases/rails to the control circuit for your next design. Our Isolation amplifiers, working in conjunction with shunt resistors, provide accurate current measurements in power converter applications in the presence of high switching noise. These devices include a built-in A/D converter and robust optical coupling technology to achieve high gain accuracy and common mode noise rejection.

Click here to learn more and register!

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