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Power Moves PUBLIC ACCESS

Developments in Electric Motors and Drives are Boosting Efficiency, Simplifying Setup, and Cutting Costs.

[+] Author Notes

Associate Editor

Mechanical Engineering 121(05), 66-67 (May 01, 1999) (2 pages) doi:10.1115/1.1999-MAY-5

This article discusses developments in electric motors and drives that are boosting efficiency, simplifying setup, and cutting costs. New drives offer compact designs and simplified installation, and start-up. An inexpensive controller for single-phase ac induction motors has been developed by Anacon Systems Inc. of Springfield, Montana. The controller is targeted to a huge installed base of fan, pump, and compressor motors. The company also has introduced a Smartcom series of motor controllers specifically designed for residential and light commercial Heating, ventilation, and air conditioning (HVAC) applications. New products currently under development by Anacon Systems will extend the range of offerings to cover power ranges up to 2 hp. The company also plans to offer controllers for three-phase motors. A new energy-efficient integrated ac drive/motor, combining plug-and-play installation and compact design, has been introduced by ABB Drives & Power Products of New Berlin, Wisconsin. The new drive has power cables at the bottom rather than on the side. The drive's compact size allows it to fit into many retrofit spaces and frees up panel space that would be occupied by a larger drive, according to ABB.

Innovations in electric motors and drives, both alternating current and direct current, are offering equipment designers benefits such as better speed control, lower power consumption, and space savings across a vast range of applications. For instance, a low-cost motion controller for single-phase induction motors offers multiple speed capability usually achieved with more expensive motor designs, or with external relays or electronics. New drives offer compact designs and simplified installation and startup.

An inexpensive controller for single-phase ac induction motors has been developed by Anacon Systems Inc. of Springfield, Mo. The controller is targeted to a huge installed base of fa n, pump, and compressor motors.

The company's Digi-Drive motor controllers let original equipment manufacturers implement variable-speed ac induction systems at a cost comparable to de motor alternatives. Multiple speed capability usually requires complex and expensive motor designs with multiple windings and external relays and electronics, explained Anacon Systems' vice president of sales and marketing, Bill Shepherd. On the other hand, single-speed motors set rotation speed by the existing line frequency of 50 or 60 Hz.

Anacon Systems' motor controllers enable a low-cost, electronic control system that can be set by the OEM designer, providing improved efficiency at speeds below the line frequency. The chip also has a great deal of programmability, allowing the speed of the motor to be varied based on an input signal. For example, this allows a motor to turn itself on in reaction to a change in pressure or temperature, reach the desired speed, and turn itself off again. The programming capability may eliminate the need for external apparatus to control and sense the speed, Shepherd added.

The Digi-Drive series of motor controllers ranges from 250 watts through 900 watts, 110 and 220 volts, to drive up to 0.5-horsepower single-phase ac motors. A sample kit of the 900-wattl1 O-amp controller is available for $195; OEM quantities should sell for less than $65. Shepherd estimates that the cost of the Digi-Drive controller and motor combination is about 15 to 18 percent less than a dc motor and controller package.

The company also has introduced a Smartcom series of motor controllers specifically designed for residential and light commercial HV AC applications. This is exactly the same footprint and motherboard, but also includes a daughterboard that contains trim pots needed for the tuning of heating and air conditioning systems, LEDs for troubleshooting when there is a disruption to the HVAC system, and an enclosure. The controllers can handle blowers up to 0.75 hp, which account for 90 percent of residential heating and air conditioning systems. It retails for $135.

New products currently under development by Anacon Systems will extend the range of offerings to cover power ranges up to 2 hp. The company also plans to offer controllers for three-phase motors.

A new energy-efficient integrated ac drive/motor, combining "plug-and-play" installation and compact design, has been introduced by ABB Drives & Power Products of New Berlin, Wis. Combining the electronic controls and motor into one unit is a relatively recent design innovation developed over the last few years, made possible with the advent of higher-grade electronics and potting compounds, said John Fassbender, ABB's product manager of ac motors. The new integral motor combines an ac motor; an integrated frequency inverter, which changes the voltage-frequency relationship in the power delivered to the motor; and an EMC filter, which prevents harmonics from affecting the service life of the motor and drive, within the unit.

The motor includes more than 50 motor/inverter parameters, to provide fast, easy installation, startup, and efficient operation, according' to ABB. The motor is installed by connecting it to the 380-460V ac supply voltage, setting the speed, and running the load. Application-specific settings can be adjusted on the unit's control panel.

The design eliminates cabling between the drive and the motor, which can introduce harmonics capable of damaging the motor's insulation. The design also protects the drive electronics from vibration. Because the drive is located at the end of the motor, it encounters less severe axial vibrations and less heat, compared with other squirrel-cage integral designs in which the drive is located on top of the motor.

"The design lengthens the profile of the motor, easing clearance into tight or existing spaces, and 100 percent of airflow from the motor's fan is cooling the inverter," said Fassbender. The integral motor's design places an inverter at the nondrive end of the unit, where the inverter and motor are both cooled more efficiently by a single fan. It's available in a 1-10 hp range (50 or 60 Hz, 380-460V ac), providing variable-speed operation in either direction. The low-speed version operates at 300-3,000 rpm at 50 Hz and 360- 3,600 rpm at 60 Hz; the high-speed version operates at 300-6,000 rpm at 50 Hz and 360-7,200 rpm at 60 Hz.

Because the integral motor can provide low-to-high rotational speeds on an "as needed" basis, it may also eliminate the use of gear products as well as the need for noisy peripheral equipment such as motor throttling devices for pumps and vane control fans, according to Fassbender. The result is operating equipment that is quieter-mean noise levels of the pump or fan units are reduced by 50 percent compared with squirrel-cage integral motor designs.

Baldor Electric Co. of Fort Smith, Ark., has improved the efficiency of its Super-E ac motors. The company has raised the efficiency of more than 125 individual ratings, and some now exceed 96 percent. The improved efficiencies meet or exceed new rebate levels established by the Consortium for Energy Efficiency that is followed by many energy utilities. The Super-E motors are available fron1. 1 to 500 hp. The line also includes chemical processing motors up to 400 hp, C-face to 25 hp, explosion-proof through 60 hp, and close-coupled pump ratings up to 50 hp. Baldor has also boosted its ac motor line to 1,000 hp.

A new compact drive for dc motors has been developed by ABB Drives & Power Products. The new drive is the smallest in its class, according to Erwin Ledderhos, manager of dc drive sales. ABB's patented integrated field supply reduces the Des 400 wiring requirements to a simple three-in, four-out configuration, as the field supply is connected in parallel to the armature current. Measuring 10.75 inches wide, the new digital Des 400 is available as a regenerative or nonregenerative unit. It covers a 5-500 hp range, with input voltages of 230- 500V at 50 or 60 Hz, and has an output current range of 20-820 amps dc.

The drive is designed for the OEMs' and dc motor owners' need for simplicity, ease of integration, and plug-and- play quality that ensures precise speed and torque accuracy, and robust performance, according to Ledderhos.

The new drive has power cables at the bottom rather than on the side. The drive's compact size allows it to fit into many retrofit spaces and frees up panel space that would be occupied by a larger drive, according to ABB. The Des 400 unit is small enough so that two can be installed side-by-side in the same 23.75-inch cabinet.

The Des 400 drive also uses a fully integrated, built-in IGBT -based three-phase field supply, which eliminates the need for wiring on the input side of the converter and the need for a voltage-matching transformer. ABB says these features make the drive smaller and improve motor commutation, reduce power loss and cabling, and improve reliability. Bottom plate entry to the drive provides rapid, easy access to the power terminals and the I/O connections, says ABB. Startup time can be as short as 15 minutes, with the help of the drive's Commissioning Wizard, which guides the user through the startup procedure. After startup, the Des 400 automatically tunes the armature current, speed, field current, and flux. Built-in application macros simplify tailoring the Des 400 for specific applications, requiring only a few user-selected parameters.

ABB coupled its Des 400 drive with a new DM! dc motor for applications requiring precise high torque at all speeds. The new dc motor features laminated construction and a 40-482 hp range, providing high power and torque in proportion to its frame size throughout the entire speed range. The motor offers high torque quality, higher top speed range, and faster acceleration and deceleration than preceding dc motors, and provides extremely smooth load operation at low speeds and high speeds, according to ABB.

A flexible terminal box that can be mounted on top or on the long sides of the DMI motor has 12 options for cable entry. Other features include a low-noise, high-speed fan that can be mounted in six different positions.

A new two-wire brushless dc motor has been introduced by the Rotron Technical Motor Division of Ametek in Kent, Ohio, as a drop-in replacement for ' brush-type dc motors. The new Dura-Tek 3.0 motor is said by the manufacturer to provide reliable performance and superior life at a cost that is comparable to brush-type dc motors. With its 3-inch outside diameter, the Dura-Tek possesses complete interchangeability with brush motors, according to Ametek.

The motor has a two-wire electrical hookup versus the eight-wire configuration typical of most brushless dc motors. The two-wire hookup is accomplished by integrating the electronics into the motor. Additional features include multispeed operation, over-temperature shutoff, and transient over-voltage operation, as well as environmentally resistant design that offers protection against hazardous operating conditions.

A new generation of DMI dc motors from ABB Drives & Power Products features laminated construction and 40-482 hp. providing high power and torque in proportion to frame size throughout the entire speed range.

Copyright © 1999 by ASME
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