Going green in powertrain and engine testing

Flexible test machines that regenerate energy promise to revolutionize the world of aircraft and automotive subsystem testing.


New flexible test machines could revolutionize aerospace and automotive subsystem testing. Courtesy: Red VikingTesting aircraft subsystems is, by necessity, an exacting process. With crew and passenger safety resting on the outcome, no one would argue about the need for these tests to be reliable. 

That’s also why historically there have been few complaints about the amount of time—and energy—these tests typically consume. However, that doesn’t mean aircraft manufacturers wouldn’t welcome a more efficient method of proving their products’ flight readiness. 

In fact, the U.S. Dept. of Defense (DoD) already is taking delivery of a new generation of helicopter test equipment that will drastically reduce the time, dollars, and energy expended in testing aircraft powertrains. The DoD will be replacing 20 aging dedicated test stands with five new flexible test machines. 

These new test systems will allow the DoD to institute new streamlined testing processes that sidestep the labor-intensive setup and tear-down that accompanies the use of current-generation test stands. Eliminating these steps will enable aircraft manufacturers to conduct multiple testing operations in a single shift, as opposed to the single test most can conduct today. 

The potential energy savings are even more impressive. Using just one of these new systems to test transmissions at a U.S. Army helicopter repair center is expected to yield $500,000 in energy cost savings in a year. 

Reducing lost energy

These savings are possible because these new systems regenerate energy during the testing process. That’s a sharp contrast from the test systems currently employed by most aerospace manufacturers, which lose 100% of their energy in the form of wasted heat. 

This new class of electrical regeneration test systems can capture most of that energy to be put back into the power grid or used to run the machine itself. In most cases, electrical regeneration systems are less expensive to build, have lower operating costs, require less maintenance, and have greater reliability. When compared with traditional testing systems, these systems will pay for themselves over time. 

Traditional braking technology wastes energy by converting power to lost heat. Courtesy: Red VikingThe basic premise of electrical regeneration is to replace traditional energy-wasting braking methods with a method that produces recoverable energy, which is then fed back into the machine or the local power grid. The commercial automotive industry has been an early adopter of this technology, with large numbers of electrical regeneration dynamometers being used to test engines and powertrain components. 

The previously mentioned DoD repair center currently is using test stands built decades ago to fulfill a single purpose, requiring excessive energy consumption and heavy cost expenditures. Thus, the DoD’s willingness to replace more than 20 dedicated powertrain test stands with five flexible systems that can test multiple transmissions and gearboxes.  

The current helicopter transmission and gearbox test systems use traditional braking technology that results in wasted energy by converting power to lost heat. 

For the DoD helicopter project, electrical regeneration systems use a common dc bus architecture, which allows for only one ac to dc conversion in the motoring direction. The regenerative braking power goes straight to another inverter, which is motoring via the common dc bus link. This method eliminates two conversion points where energy would be lost and increases overall efficiency. 

New electrical regeneration test systems use a common dc bus architecture. Courtesy: Red VikingIn addition, the common bus solution paired with the active front end (AFE) has the ability for power factor correction, further increasing the overall savings of a common bus system. All AFE drives allow for unity power factor and low total harmonic distortion (THD) that meets IEEE 519 harmonic standards, which allows the drive systems to improve the present power factor displacement in the customer’s facility. 

The energy savings on this project have exceeded expectations. The new systems are six times more energy efficient than the single-purpose helicopter test stands. The new system designed for testing the main transmission—when running at full capacity—will cost approximately $400 less per hour to operate than current systems. 

The potential for energy savings is even greater with turbo shaft engine test centers, which can lose as much as 5.5 million kWh of electricity during a typical year, enough energy to power 1,500 residential homes. 

Current turbo shaft engine test systems use water braking technology that results in wasted energy by converting power to lost heat. 

In addition to wasting energy, there are other disadvantages to using liquid brake test systems. The high rate of energy conversion taking place inside the brake erodes the internal components, requiring them to have to be rebuilt or replaced more often. With these frequent maintenance activities impacting the system’s structure and alignment, test data accuracy and repeatability are jeopardized. Also, the erosion process is sensitive to the quality of the incoming cooling water, which must be continually filtered and chemically treated, adding cost to the testing process.

By selecting an electrical regeneration engine test system, these disadvantages are avoided, and most of the test system’s energy can be fed back to the power grid in the form of electricity. This type of engine test cell technology is analogous to wind turbines, using essentially the same conversion equipment, switching gear, and energy management systems.

Showing global potential 

Traditional turbo shaft engine testing center. These systems have numerous disadvantages. In addition to wasting energy by converting power to lost heat, their braking mechanisms erode internal components, requiring them to be rebuilt or replaced more oftGlobally, electrical regeneration systems are being used in many other ways for energy conservation, including: 

  • The Delhi Metro has reduced its power requirements by 30% since 2009 by using electrical regeneration in train braking systems.
  • Building elevators with electrical regeneration technology reduce energy costs by 20% to 40%, with the energy being used to power the building. Here’s a hotel in Africa that captures 30% of the elevator’s power and returns it to the building. 

At least one test system supplier already is designing and building a wide array of mechanical and electrical energy regenerating test systems for the aerospace, automotive, and heavy vehicle industries and is committed to incorporating energy-saving technologies into all its designs. This technology promises to revolutionize the world of engine and powertrain testing. 

Jason Stefanski is controls and software manager for Red Viking, a supplier of highly engineered test systems for the aerospace, heavy vehicle, and automotive industries. For more information about using electrical regeneration in engine and powertrain testing, visit www.redviking.com.

This article is part of the Industrial Energy Management supplement for CFE Media publications. 

See the links at the bottom of this article to read other articles in this supplement.

Jouko , Non-US/Not Applicable, Finland, 10/11/13 03:22 AM:

This is not actually new technology in helicopter gearbox testing. Renk and ABB delivered such system for Westland already in 1999.

Mark , IL, United States, 10/11/13 12:02 PM:

Thanks very much for your comment. Test stands continue to be a great application for regeneration energy savings. At the top of www.controleng.com search for "test stand regen" to see other examples of Control Engineering coverage on this topic. To share details of your applications, please consider writing a tutorial or case study: www.controleng.com/contribute -- thanks!
The Top Plant program honors outstanding manufacturing facilities in North America. View the 2013 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
The true cost of lubrication: Three keys to consider when evaluating oils; Plant Engineering Lubrication Guide; 11 ways to protect bearing assets; Is lubrication part of your KPIs?
Contract maintenance: 5 ways to keep things humming while keeping an eye on costs; Pneumatic systems; Energy monitoring; The sixth 'S' is safety
Transport your data: Supply chain information critical to operational excellence; High-voltage faults; Portable cooling; Safety automation isn't automatic
Case Study Database

Case Study Database

Get more exposure for your case study by uploading it to the Plant Engineering case study database, where end-users can identify relevant solutions and explore what the experts are doing to effectively implement a variety of technology and productivity related projects.

These case studies provide examples of how knowledgeable solution providers have used technology, processes and people to create effective and successful implementations in real-world situations. Case studies can be completed by filling out a simple online form where you can outline the project title, abstract, and full story in 1500 words or less; upload photos, videos and a logo.

Click here to visit the Case Study Database and upload your case study.

Maintaining low data center PUE; Using eco mode in UPS systems; Commissioning electrical and power systems; Exploring dc power distribution alternatives
Synchronizing industrial Ethernet networks; Selecting protocol conversion gateways; Integrating HMIs with PLCs and PACs
Why manufacturers need to see energy in a different light: Current approaches to energy management yield quick savings, but leave plant managers searching for ways of improving on those early gains.

Annual Salary Survey

Participate in the 2013 Salary Survey

In a year when manufacturing continued to lead the economic rebound, it makes sense that plant manager bonuses rebounded. Plant Engineering’s annual Salary Survey shows both wages and bonuses rose in 2012 after a retreat the year before.

Average salary across all job titles for plant floor management rose 3.5% to $95,446, and bonus compensation jumped to $15,162, a 4.2% increase from the 2010 level and double the 2011 total, which showed a sharp drop in bonus.

2012 Salary Survey Analysis

2012 Salary Survey Results

Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Society for Maintenance and Reliability Professionals an organization devoted...
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.