But the Radford, Va.-based motion-control engineer with vendor Danaher Motion (www.danahermotion.com), of Wood Dale,
And less cable equals smaller footprint. For example, Bosch-Rexroth Corp.’s (www.boschrexroth-us.com) IndraDrive Mi product combines control electronics and servo motor into a single, highly compact drive unit. This reduces the drive’s size by 50 percent, compared to traditional servo solutions, says Rami Al-Ashqar, product manager in Bosch Rexroth’s Electric Drives and Controls Group in
Get outta there
In addition, cabinet space is also reduced, points out Carl Owens, application engineer with the Production Machines/Drive Technologies Group within vendor Siemens Energy & Automation Inc. (www.sea.siemens.com), in Norcross, Ga. “Our end-users are typically used to large control cabinets, which sometimes are mounted next to the machine,” Owens observes. But he’s seen demand increase in the past two years for decentralized systems, Owens adds, because “people realize there’s a cost savings” due getting out of the cabinet.
“We want to reduce panel size and floor space—and take as much of the motor control as possible and put it near to, or on the motor,” adds Darlene Acklin, a product manager for Lyman, S.C.-based SEW-Eurodrive USA’s (www.seweurodrive.com) decentralized products group, another vendor in the space. That means taking overload, brake control and variable-frequency drives, as well as communications for any fieldbus, out of the control cabinet.
These decentralized systems also provide more potential input/output (I/O). Jan Lindholm, SEW-Eurodrive industry account manager, adds that with his company’s current generation of Movofit field distributors—or decentralized control units—up to 16 I/O are possible with each unit.
End-users “see that equipment costs and capital costs are less. They also see that installation time is shorter,” Lindholm observes. For example, for a line of 50 motors and a 600-foot conveyor belt, he estimates that a centralized system would need approximately 9,700 feet of power cable. “But if you have a decentralized system, you need only about 1,200 feet.” To install the centralized drives would require almost 300 hours of labor, he approximates. “But for the decentralized system, you’d need about 40 hours.”
Putting motion control and logic on a motor also enables original equipment manufacturers to pre-commission the motors in the warehouse, Lindholm points out.
But at least one potential downside exists for motion control-in-a-box: reliability and maintenance. “You [may] have heat sources—the motion controller and the motor—coupled in the same housing. So, temperature becomes a critical parameter,” warns Matheus Bulho, product marketing manager in Rockwell Automation Inc.’s (www.rockwellautomation.com) Kinetix Motion Control Group, in
Regardless, outside of the automotive industry,
C. Kenna Amos, email@example.com, is an Automation World Contributing Editor