ABB Introduces Patent-Pending Swinging Choke Drive Technology Reducing Harmonics at Partial Load |

ABB Introduces Patent-Pending Swinging Choke Drive Technology Reducing Harmonics at Partial Load

February 062004
Up to an additional 30%, compared to traditional choke designs

NEW BERLIN, Wis., February 2004 . . . "If you claimed that the sole purpose of a variable-speed motor drive was to increase energy efficiency, it would be no exaggeration, of course," says Mark Kenyon, product manager, ABB Inc., Automation Technologies, Drives "That's what they're designed for.

"But one of the truly unique features of the new ACS550 drive for industrial applications is that it employs a groundbreaking Swinging Choke technology to reduce harmonics at partial load, making an essentially efficiency-driven solution that much more efficient - at zero added cost to the user," he noted. "What's more, ACS550 drives makes precise motor control easier than ever before."

Motors powering mechanical equipment consume an astounding amount of energy. They account for a full 60% of the total electrical energy consumed in the U.S., for example. And when motors run at a fixed speed, much of the energy they use is simply wasted. Variable speed drives, like the ACS550, precisely control motor speed to reflect actual demand, eliminating waste caused by fixed-speed operation and generating end-user savings of up to 70%.

Even so, current harmonics cause energy loss in devices operating with variable speed drives. Harmonics are electrical disturbances generated by non-linear devices (just about anything with a microprocessor)
connected to the supply system. Current harmonics squander energy by causing excessive transformer heat loss. In addition, current harmonics require expensive compensation in the form of oversized cabling and can cause sensitive equipment to malfunction.

Reduced Harmonics at Partial Load

Use of conventional chokes or line reactors bring down harmonic levels at full load to meet existing standards, but do nothing to reduce them at partial load. Since devices operating with a variable speed drive operate at partial load most of the time, reducing harmonics at partial load can lead to savings in transformer heat losses. Through ABB's patent-pending Swinging Choke design, the ACS550 reduces harmonics at both full load and partial load for a total reduction of up to 30% compared to traditional choke designs.

"The Swinging Choke is important because it provides increased inductance at reduced current, something that quite literally has never been done before," according to Kenyon. "When users realize what a 30%additional reduction in harmonics at partial load means in terms of energy saved, lowered first costs and increased system reliability, they won't be prepared to live without it. This helps take care of an issue that is a growing concern to industry."

Design Driven by Customers' Requirements

The ACS550 is a landmark product in other respects, as well. It was the first-ever, joint-development effort between ABB in Finland and the U.S. And it's based on a needs-assessment process that asked customers worldwide what they wanted in a motor drive. As a result, the ACS550 features an intuitive keypad, modelled after a cell phone.

Standard Start-Up Assistant software rapidly guides users through set-up procedures and Maintenance Assistant software signals when it's time for routine maintenance. Plus, Diagnostic Assistant software provides users with suggestions for correcting faults.

Kenyon concludes: "The ACS550 offers precedent-setting harmonics mitigation, and it also is the easiest motor drive on the market to install, start and use benefits that our customers asked us for!"

ABB Inc., Automation Technologies, Drives, is the world's largest manufacturer of electric motors and drives. In the USA, an integrated channel of sales representatives, distributors, and system integrators allow ABB, New Berlin, Wisconsin, to supply a complete line of energy-efficient electric drives, motors and engineered drive systems to a wide range of industrial and commercial customers. Products manufactured include AC and DC variable speed drives for electric motors from 1/8th through 135,000 HP, large AC machines and drives, medium-voltage drives, power electronics and rectifier systems, AC & DC motors, and application-specific drive system solutions to meet diverse customer needs (

ABB ( is a leader in power and automation technologies that enables utility and industry customers to improve performance while lowering environmental impact. The ABB Group of companies operates in around 100 countries and employs about 120,000 people. The company's U.S. operations employ about 9,500 in manufacturing and other facilities in 40 states.
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