AC Motor and Motor Drive Technology Retrofit Boosts Production Efficiency at Wire Manufacturing Facility
The Demand for Efficiency and QualityBecause Judd Wire can produce custom wire to order, the California facility grew its customer base. In 2000, the production capacity for coaxial cable doubled, according to Don Cole, controller at San Marcos.
"A customer prospect came to us and said, 'My supplier won't listen to me; can you make this cable better?' and we said, 'Yes,'" noted Richard Paul, design engineering manager. "A core of business grew out of customer responsiveness and truly listening to, and empowering our employees to implement change."
For example, the silver-plated copper wire that Judd Wire uses, distinguishes its cable competitively. As a result, the final product is a high-quality, consistent cable that features a very high SRL. The mantra is "Every inch on the roll must be usable and well within specification."
To keep up with demand and quality requirements, electricians and mechanical engineers need the tools to build increasingly complex machines. "By building, re-fabricating and customizing our own machines," notes Greg Grace, plant manager "we can maintain nearly continuous production, improve process consistency, and produce a superior product that our customers demand. This all improves our bottom line."
Seamless Electrical Control/Mechanical IntegrationThe ability to regulate equipment speed precisely underlies product quality and production reliability. Judd Wire decided to retrofit the San Marcos production facility with electrical drive/motor control. "Instead of using line shafts with gears and belts, we now just plug in two fiber optic wires between the drives, three wires to each motor, and that's it," says Tracy Wehrung, maintenance electrician at San Marcos. "Everything else is programming the drive controls."
The conversion from traditional mechanical power to electrical drive and motor control was facilitated by ABB, Inc., Automation Technology Products Division, Drives & Power Electronics, New Berlin. The most severe electrical demands in wire production at the San Marcos facility were made by the capstan (winder) and unwinder, which regulate the draw speed of any extrusion process. The DC closed-loop electrical control was replaced with a 5 HP ABB ACS 600 motor drive on the capstan, and a 40 HP drive on the extruder. Built into these drives is ABB's open-loop Direct Torque Control (DTC) feature, which enables ACS 600 drives to calculate the torque and flux of a motor 40,000 times per second. According to ABB, this responsiveness to the motor load makes the drives tripless.
"This precision cues drives to handle changes in load, over-voltages, and even short circuits, immediately," said Rob Brown, who works alongside Wehrung building production lines and now designing control systems. "High torque at low speed is critical to multiple wire, braiding and jacketing of processes."
The motors that power the winder and drum in Judd Wire's proprietary irradiation process require stringent speed regulation: Two drives, among the very first in the ABB's AC 600 series, shipped to San Marcos from Helsinki in 1996, were installed adjacent to the irradiation room.
Encoder-less OperationEncoders are fragile glass disks that historically have been hard-wired to motors and provide exact operating speeds. They are a "weak link" in hostile processing environments, notes Wehrung, and the bane of a process like irradiation. Encoders also create electrical pulse and noise that interfere with production.
The absence of any required encoder for feedback from motor to drive can reduce capital costs for the controller by up to 25 percent, when compared to like flux vector or PWM (Pulse-Width-Modulated) drives. "A broken or failing encoder shuts down the process - and entire line," said Brown. "And it can be tricky to troubleshoot, correctly identify and fix the problem. Meantime, there's pressure to get back up and on line. Sensor-less operation eliminates all of these drawbacks in one fell swoop."
According to the Judd Wire electricians direct torque control technology is the answer. It provides real-world, working open-loop operation of motors. Even a drive with an encoder that works flawlessly doesn't touch it, Wehrung said.
To ensure repeatability of motor operation, Judd Wire uses ABB's DriveWindow tool. "We write the parameters into the software and save, download and upload it into additional drives," Grace said.
What's Up Next?What will be the new core business for Judd Wire and other producers? "That Scout motto, 'be prepared,' fits," notes Cole. The motor control retrofit of the San Marcos facility has prepared Judd Wire "to pioneer the next product, to customize a response to a request, and to build a core business around an idea that may arrive tomorrow."
ABB, Inc., Automation Technology Products Division, Drives & Power Electronics, 16250 West Glendale Drive New Berlin, WI 53151-2840; 262-785-8363.