AC Drives minimize harmonic distortion.

Press Release Summary:

ACH DriveIT 400 variable-speed AC drives are offered in 10-700 hp range at 200-4780 Vac and come in Plenum-rated NEMA 1 or NEMA 12 enclosures. Built-in impedance rating is 3%. These 12- and 18-pulse input bridge units combine phase-shifting transformer technology with 6-pulse rectifier circuit, which optimizes voltage and impedance balance and provides harmonic cancellation. All drives in series can be connected to common field bus networks.

Original Press Release:

New ABB Low Harmonic Distortion Solutions Include 12- and 18-pulse Rectifiers, Passive and Active Filters, to Provide Maximum Harmonic Control (Mitigation) Benefits to Commercial Building Users

(Demand For Filters and Drives Will Grow, As Buildings Continue To Add Electronic Devices And Accommodate Users, Says Miller)

NEW BERLIN, Wis., January 27, 2003 . . . The introduction of new harmonic control equipment, 12- and 18-pulse input bridge units, expands ABB's ACH DriveIT Low Voltage 400 variable-speed AC drive family - and offers engineers, facility managers and building owners an easy turnkey solution for minimizing harmonics in commercial installations where harmonic distortion is a critical consideration. The new drives are available in a 10 - 700 horsepower range at 200 - 480 VAC and are built in Plenum-rated NEMA 1 or NEMA 12 enclosures; most units are built to contain both the transformers and drives. When required, transformers are available in separate enclosures.

ABB's ACH 400 drives have the industry's highest built-in impedance rating/feature -- at 3%. For applications where lower levels of harmonic distortion are a requirement, ABB offers customers a Universal Harmonic Filter (UHF) from Mirus, 12- or 18-pulse rectifiers, or an active rectifier.

"The low harmonic distortion solutions deepen and broaden our product range and equip ABB to respond to a host of end-user situations and conditions," said Jeff Miller, HVAC sales manager for ABB Automation Technologies, Drives, Motors and Machines. "Commercial buildings include an ever-growing number of voltage-sensitive electronic devices - from PCs to sophisticated control systems - that make minimization of harmonics a growing concern for ensuring users' comfort."

This focus on customer needs and end-user comfort is a mantra, Miller noted. ABB is the #1 drives supplier to the U.S. HVAC market and continues to increase sales and the company's 25% market share.

Demand For Reduction of Harmonic Distortion Growing
Harmonics are currents produced by any non-linear load - 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 buildings being sensitive to harmonics.

12- and 18-Pulse ABB Drives Combine Technologies
ABB's new 12- and 18-pulse drives combine transformer technology with the 6-pulse rectifier circuit utilized in the company's ACH 400 workhorse unit. 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.

In both of the multi-pulse drives, ABB utilizes a unique phase-shifting transformer built with a proprietary winding and connection configuration that creates an ideal voltage and impedance balance (the generated harmonics are in opposite phase and magnitude to the supply side) that provides maximum harmonic cancellation - especially of the 5th- and 7th-order harmonic.

The degree of harmonic cancellation increases with each addition of a 6-pulse rectifier. While the 12-pulse drive utilizes one three-phase primary winding and two three-phase secondary windings in its transformer unit, the 18-pulse drive is built with three three-phase secondary windings. These secondary windings are then phase shifted, which produces the harmonic cancellation.

Both of the new drive units are available with an input disconnect switch or circuit breaker, bypass, and other optional equipment.

Adjustable Frequency Drives are an Applied Product, not a Commodity
"Look for demand for these drives to grow, as buildings get more crowded with electronic devices and controls designed to increase user comfort and the array of tools and devices at their fingertips," says Miller. These products need to be designed into the building in a systemic way, notes Miller, rather than being provided as a topical fix. "Harmonics are a system issue, not a product issue, so the AFD vendor needs to provide harmonic calculations to provide the best solution for the owner and comply with IEEE 519 limits," he said.

All models in ABB's ACH DriveIT Low Voltage 400 drive series can be connected to common field bus networks, including Johnson Controls, Siemens-Landis Division, Modbus, Ethernet, Devicenet, LonWorks, and others. The drives meet worldwide standards, and carry UL®, cUL®, and CE approvals.

ABB Inc., Automation Technologies, Drives, Motors and Machines, is the #1 drives supplier to the U.S. HVAC market, and has connected more than 20,000 drives to building automation systems. In the USA, ABB, New Berlin, Wisconsin, supplies a complete line of energy-efficient electric drives and motors to HVAC and commercial customers through an integrated channel of sales representatives and distributors. Products manufactured include AC & DC variable speed drives from fractional to 400 horsepower. HVAC single-motor drive applications include exhaust fans, fume hoods, re-circulation pumps, condenser fans; multiple-motor applications include multi-cell cooling towers, paralleled chilled water, and booster pump systems (

ABB ( 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.

More from Controls & Controllers

All Topics