Save time, effort, grief in designing machine controls
Decentralized control technology (DCT) promotes modular design. For instance,when adding another filler or capper to a bottling line, wires can be disconnected, moved, and plugged in again, instead of rewiring and recommissioning, which saves labor and downtime.
Decentralized control technology (DCT) promotes modular design. For instance, when adding another filler or capper to a bottling line, wires can be disconnected, moved, and plugged in again, instead of rewiring and recommissioning, which saves labor and downtime. New installations also benefit.
Skip Ward, VP of research & development at SpanTech , an OEM of conveyors using SEW-Eurodrive ’s decentralized control technology (DCT), says, "To determine cost efficiency, we did several projections before deciding on the DCT system. We quoted DCT and standard configurations. The biggest system was 112 motors; it included 1,536 photo controls and 1,536 solenoid controls. The system was designed to use DCT in conjunction with DeviceNet industrial commu-nication protocol. To supply all materials, the components cost $18,000 more initially, but the estimated installation cost for the whole system was $20,000 for electrical (distributed) installation compared to $180,000 to $200,000 for standard installation. So there is a monumental savings in the installation. The increased upfront investment in components is very minor compared to the installation cost savings."
Ward says DCT allows all control from one main electrical panel. "We like DCT because the electrical system is quick and easy. It’s ideal for conveyors. Moving the drives out of one cabinet eliminates all the cumbersome wiring."
For more on SEW DCT from Control Engineering , click here .
Here’s a summary of considerations for any machine control project.
1. Plan, research, study, and quantify benefits.
2. Use standards.
3. Employ on-board smart sensors, machine vision.
4. Select appropriate hardware and software platforms for logic, and for preservation of intel-lectual investments through the product lifecycle.
5. Consider the advantages that advanced electronics and software can have on actuation, in-cluding motors and motion controls.
6. Evaluate benefits of screen-based human-machine interfaces versus pushbuttons.
7. Don’t hardwire; use networks and communications (including machine to machine, M2M), for better communications, internal and external to the machine.
8. Simplify by buying power-related components, rather than designing your own power bus, power supplies, and power-management devices.
9. Think beyond the machine and integrate controls with safety, environmental concerns as well as with other machines and plant and enterprise systems.
10. Record what you learned working with staff, vendors, system integrators, customers, and oth-ers on and beyond the project team to lay the groundwork for the next project.
These recommendations are based on an upcoming article and online extra in Control Engineering ’s October 2004 North American issue.
—Mark T. Hoske, editor-in-chief, Control Engineering, MHoske@cfemedia.com
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