Paper machine retrofit pioneers encoder-less drive operation

Encouraged by efficiencies gained following installation of ABB's (New Berlin, Wis.) 100-, 150- and 350-hp drives, motors and controls on its presses several years ago, engineering managers at Georgia-Pacific (G-P) Gypsum paper mill (San Leandro, Calif.) recently retrofitted the mill's finishing end too.


Encouraged by efficiencies gained following installation of ABB's (New Berlin, Wis.) 100-, 150- and 350-hp drives, motors and controls on its presses several years ago, engineering managers at Georgia-Pacific (G-P) Gypsum paper mill (San Leandro, Calif.) recently retrofitted the mill's finishing end too.

"The drives, synchronized to the existing line shaft via encoders that provided feedback of line speed, freed up horsepower to the steam turbine, so the whole paper machine could speed up," says Chris Hall, president of Intec Solutions, a systems integrator that performed both upgrades. Also, the motor controllers now provide more precise draw control, which enables tighter draws and fewer paper breaks.

Built in 1952, and acquired by G-P in 1996 from Domtar Gypsum, the 400-ft mill and its steam-turbine-driven paper machine supplies eight-ply face- and back-side paper to other G-P Gypsum board plants at a maximum capacity of 750 fpm. Before the mid-1990s upgrade, heat and wear caused steam-driven turbine failures and downtime.

Common bus = less equipment

Fred Curcio, G-P's plant manager, and Intec next discussed the complete retrofit of the finishing end, including its dryer section, calendar stack and reel. "We designed completion of the project for 1,000 fpm," says Mr. Curcio.

Intec's solution: build and install a multi-drive with seven ABB ac motor drives, ranging from 40-125 horsepower, all connected to a common 700-V dc bus supply. The common bus is the power supply to each drive, which eliminates the three-phase supply in a shared-bus configuration. Input power semiconductors and pre-charge hardware is eliminated from all drives.

"Common bus also eliminates the need for added reactors in front of each drive to provide filtration," adds Mr. Hall. Using ABB's ACS 600's open-loop Direct Torque Control (DTC) technology also eliminated the need for encoders on the finishing end. ABB reports that DTC enables each machine's motor drive to calculate the state—torque and flux—of the motor 40,000 times per sec, making the drive virtually trip-less.

Going encoder-less

Seamless operation of the finishing end enabled removal of encoders from the paper machine's forming end. Mr. Curcio and Mr. Hall say encoders were the "weakest link" in the electrical chain. If the glass disks fail or short out, the processing line stopped until the specific encoder is found and replaced.

Also, Intec replaced the PWM drive on the third press with an ABB DTC drive, creating a mini multi-drive between the second and third press. "The second press is operated in torque, not speed, mode at a set-point, so the third press drive uses that generated energy," says Mr. Hall.

"Encoder-less operation of a paper mill is a quantum leap in simplification," adds Mike Giraudo, Intec's vp. "Mechanically, the encoders and wiring to them cease to be necessary."

Following an ambitious four-day installation of the multi-drives, stand-alone ACS 600 drives, and a motor control room, G-P's paper machine was making paper within two hours of start-up on the fourth day of the retrofit in March, 1999.

Two years later, the mill is presently producing heavier paper, for use in G-P's ToughRock wallboard. Increased throughput capacity has let the mill increase tonnage of this heavier paper from 175 to 225 tons per day. Machine delay is minimal. "We're down to 2% during many months, which is 5% below the industry average, " says Mr. Curcio, who adds the 13 DTC drives on the paper machine have operated without a hitch.

For more information, Circle 499 or visit .

Author Information

Jim Montague, news editor

No comments
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by...
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
Additive manufacturing benefits; HMI and sensor tips; System integrator advice; Innovations from the industry
Robotic safety, collaboration, standards; DCS migration tips; IT/OT convergence; 2017 Control Engineering Salary and Career Survey
Integrated mobility; Artificial intelligence; Predictive motion control; Sensors and control system inputs; Asset Management; Cybersecurity
Featured articles highlight technologies that enable the Industrial Internet of Things, IIoT-related products and strategies to get data more easily to the user.
This article collection contains several articles on how automation and controls are helping human-machine interface (HMI) hardware and software advance.
This digital report will explore several aspects of how IIoT will transform manufacturing in the coming years.

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

Infrastructure for natural gas expansion; Artificial lift methods; Disruptive technology and fugitive gas emissions
Mobility as the means to offshore innovation; Preventing another Deepwater Horizon; ROVs as subsea robots; SCADA and the radio spectrum
Future of oil and gas projects; Reservoir models; The importance of SCADA to oil and gas
Automation Engineer; Wood Group
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me