Technologies Of The Year -- MagnaDrive Adjustable Speed Drive

Imagine an easy-to-install industrial technology that reduces energy consumption, eliminates mechanical vibrations and electronic harmonics, relaxes alignment tolerances and cuts maintenance needs.

Sound too good to be true?

"This is something that no one even knew was possible," says Ken Black, senior applications engineer for MagnaDrive Corp., Seattle. "This is a new animal in the zoo."

The MagnaDrive Adjustable Speed Drive (ASD) is based on the principles of standard AC eddy current variable speed drives but does not need an AC motor to create the electromagnetic fields. The MagnaDrive ASD uses powerful rare-earth Neodymium-iron-boron (NdFeB) magnets that are far more powerful than conventional iron magnets. The magnets, which became commercially available in the early 1980s, retain their properties for more than 20,000 years and endure temperatures up to 350 F.

"I see this technology as so innovative and so disruptive to rotating equipment, that I believe there will be applications that are going to drastically change how industry manages torque in the future because of it," says Ron Woodard, president and CEO of MagnaDrive.

In the construction of a MagnaDrive ASD, a plate studded with NdFeB magnets is connected to the system load, while a copper conducting plate is connected to the motor. As the motor rotates, the relative motion between the magnets and the copper plate creates a magnetic force arising from eddy currents induced in the copper plate. This force causes the load to turn. The amount of torque applied to the load is controlled by the width of the air gap between the motor and load. A smaller air gap increases the magnetic fields at the copper plate and increases the torque.

The ASD delivers the energy savings and speed control benefits associated with variable frequency drives (VFDs) but is easier to install and maintain because it is a mechanical rather than a computer/electronic technology. According to MagnaDrive, installations of their ASDs have allowed motors to be run with energy savings of up to 66% depending upon the application.

Additionally, the MagnaDrive ASD differs from conventional drives by having the motor disconnected from the load. Vibrations that may occur on one side of the air gap are not transmitted, meaning less wear on motor parts, lower maintenance costs, and increased motor life when compared with conventional drives. This disconnection also enables the motor to be run on inconsistent electrical power, unlike VFD systems, which can be damaged by inconsistent power. This can be a significant advantage in emerging markets. Another advantage of the motor/load disconnection is that it enables the MagnaDrive ASD to be "soft started". It allows the motor to operate at its optimum running torque and eliminates the need for a higher start-up torque, which is needed with conventional motors because they have to start themselves and the load simultaneously. In the MagnaDrive ASD, the motor and load can be started separately. In a number of MagnaDrive ASD installations, this allows the use of smaller motors and eliminates power spikes or brownouts.

To date, MagnaDrive ASDs have been used primarily in retrofitting existing systems where vibration, energy consumption or maintenance costs were known problems. The company started full-scale sales in 2001 and, as of October, has 56 installations at 36 customer sites. Current customers span a variety of industries including waste/wastewater treatment, pulp and paper, HVAC, material processing, irrigation, food processing and power generation.

The Rock Creek Wastewater Treatment Facility in Hillsboro, Ore., installed a MagnaDrive ASD on one of two 60 horsepower motors that were constantly being replaced due to excess vibration.

"[We were looking for] a lower maintenance, lower tech alternative to variable frequency drives," says Nathan Cullen, principal engineer at Rock Creek.

Use of the ASD enabled the removal of a bypass valve, the complete elimination of one of the motors and the reduction of the remaining motor from 60 horsepower to 20 horsepower. According to Cullen, "No maintenance has been required in the first year of operation," an improvement over the previous system.

PORTAC Inc., a supplier of lumber cut for home construction, installed a MagnaDrive ASD on a 125 horsepower belt drive draft fan located at its Forks, Wash., facility. The existing system required that the fan run at full speed, using dampers to maintain the pressure in the system. Additionally, there was a large amount of vibration to the motor and nearby areas. The inclusion of a MagnaDrive ASD allowed the dampers to be removed, and the system to operate more efficiently. Dave Claussen, plant manager at PORTAC, says the initial benefit was a reduction in energy consumption of more than 200,000 kilowatt-hours, saving the facility more than $12,000 annually. PORTAC also noticed a drastic reduction in equipment vibration with corresponding reduced maintenance.

"We have VFDs all over our operation [but] you can't work on them yourself," Claussen says. "There are a multitude of things that can fail, and they're all electronic. MagnaDrive is very simple. There's not much to fail."

Market potential for MagnaDrive ASDs is attractive. Research by the Northwest Energy Efficiency Alliance (NEEA) trade group, Portland, Ore., estimates the speed control market for MagnaDrive ASDs to be at $1.6 billion per year, primarily concentrated in the HVAC, industrial and wastewater system areas. NEEA, which has a partnership with MagnaDrive, further estimates that the international market is more than double the U.S. market.

In January 2001 MagnaDrive was awarded a $500,000 grant from the Department of Energy as part of the National Industrial Competitiveness Through Energy, Environment and Economics program to implement the ASD technology in industrial applications requiring larger (500 to 1500 horsepower) motors. MagnaDrive also is extending the principles behind its ASDs to industrial couplings on constant speed drives in the 20 to 1000 horsepower range. These MagnaGuard couplings use the same magnetic torque transfer principles and have just become available.

The company also is conducting research into applications involving transportation and maritime systems and is actively seeking partners in these areas.