ABB Evaluates Conditions, Provides Recommendations and Control Options/Solutions, If and When Harmonics Generated from Drives Are A Concern | Automation.com

ABB Evaluates Conditions, Provides Recommendations and Control Options/Solutions, If and When Harmonics Generated from Drives Are A Concern

(Following Analysis, Filters and Drives Designed for Harmonic Mitigation Help to Keep the Power Supply Clean)

NEW BERLIN, Wis., March, 2003 . . . “The real place to begin on the question of harmonics is with a customer’s specific situation – provide an analysis of what a given drive or drives will add to the harmonic mix, and then recommend the best solution (product and cost) for mitigating excessive harmonics,” points out John Tisdale, sales manager for the new ACS 800 drive line, ABB Automation Technologies, Drives, Motors and Machines.

Demand For Reduction of Harmonic Distortion Growing
Harmonics are currents produced by any non-linear load (such as UPS systems, computers, electronic lighting, variable speed drives) and are multiples of 60 Hz. Because harmonics can increase as more devices are added to a common transformer, management of the resulting harmonic distortion is growing in demand and importance, according to ABB. Harmonic distortion can result in mis-operation of sensitive electronic equipment and generators. Harmonics are more of a concern today due to two factors: the extensive use of harmonic-generating equipment; and more of the equipment installed in stand-alone machines and processing lines being sensitive to harmonics.

Common applications where these ABB drives now are being installed include large-horsepower extruders for the plastics industry and on MVR (Mechanical Vapor Re-compression) fans used in cheese-processing facilities, plus pharmaceutical and water-treatment applications, to name just a few examples. Specific industrial plants and OEM machines include an ever-growing number of voltage-sensitive electronic devices that make minimization of harmonics a growing concern, Tisdale noted.

ABB Expands Harmonic Mitigation Equipment
ABB’s ACS DriveIT Low Voltage 800 variable-speed AC drives have the industry’s highest built-in impedance rating/feature -- at 3%. This satisfies 85 percent of the harmonic mitigation requirements of industrial applications, according to Tisdale.

For applications where additional harmonic mitigation is a requirement, ABB offers customers a number of solutions. For low levels of harmonics above the 3% range in general applications, the company offers: 1) additional reactance on the 3-phase power line; 2) tuned filters; 3) 12-pulse solutions; 4) a Universal Harmonic Filter (from Mirus), which is installed as a unit between incoming power cables and a drive(s); and 5) an active front-end drive, exceeding the performance of a 12-pulse drive.

Application-Specific Mitigation
ABB’s new 12-pulse drives combine transformer technology with the 12-pulse rectifier circuit utilized in the company’s drives series, for more challenging installations. The 6-pulse diode bridge, the most common rectifier circuit used in 3-phase AC drives, consists of six diodes and an inductor; together with a DC-capacitor, this circuit forms a low-pass filter that smoothes the DC current. This drive/technology is used in most applications.

The degree of harmonic cancellation increases with each addition of a 6-pulse rectifier. The 12-pulse drive utilizes one three-phase primary winding and two three-phase secondary windings in its transformer unit. These secondary windings are then phase shifted, which produces the harmonic cancellation.

And the ultimate solution for harmonic mitigation – ideal for installations such as very long ski lifts – is the ACS 817 drive, which features IGBT-based switch construction in the AC drive’s front end (regenerative) and combines with ABB’s unique built-in LCL filter, to dramatically lower harmonics. “The active filter, which shapes the current sinusoidally, outperforms,” according to Tisdale. By comparison, “the harmonics generated by a typical DC drive would be approximately seven times those generated by this regenerative AC drive,” he noted.

These low harmonic distortion solutions deepen and broaden ABB’s product range and equip the company to respond to a wide spectrum of situations and conditions, company experts noted. “It helps equip our engineers and sales channel with turnkey solutions for minimizing harmonics in applications where harmonic distortion is a critical consideration,” Tisdale said.

Adjustable Frequency Drives Keep Power Supply Clean
“Look for demand for these drives to grow, as industrial operators are asked to comply with utility and power-generation standards and minimize distortion to the power supply,” Tisdale said.

Virtually all units in ABB’s ACS DriveIT Low Voltage drive series meet worldwide standards, and carry ULÒ, cULÒ, and CE approvals.
ABB Inc., Automation Technologies, Drives, Motors and Machines, 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 variable speed drives for electric motors from 1/2 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 (http://www.abb-drives.com).

ABB (www.abb.com) is a leader in power and automation technologies that enable utility and industry customers to improve performance while lowering environmental impacts. The ABB Group of companies operates in more than 100 countries and employs about 146,000 people worldwide. The company's U.S. operations employ more than 14,000 people in manufacturing and other facilities in 40 states.
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