Busway installation gives electronics manufacturer new flexibility.
Specifically, the change was precipitated by the need to add 20 customer-provided environmental testing chambers to evaluate repaired circuit boards for temperature extremes. The chambers utilize a l-ton compressor that cycles temperatures inside from 0 to 50 degrees Celsius in seconds. To meet the mandate, each chamber required 60A/three-phase electrical service.
At issue was the plant's floor-based metal raceway that provided power to the 9 x 50-ft. work cells built around the raceway. The company could have tapped into the raceway at any point, but doing so required cutting power to the line, thus interrupting workflow. Plus, production equipment and furniture nearby had to be moved for any change, creating further interruptions. But the biggest issue was the amount of electricity that would be necessary to power the chambers to meet the customer's testing mandate--which would mean numerous individual raceway connections.
"We didn't have enough circuits," says Steve Ball, Solectron's senior process engineer. "We would have had to pull a big main into the building to be able to handle up to 40 of these chambers at 60A each. It was the high demand for electricity by the equipment that caused us to rethink our strategy."
The rethinking process eventually centered on altering the power infrastructure for the job--removing the floor-based raceway in the affected work cells and replacing it with busway running along the ceiling of the facility. Initial concern about the effect of added weight on the facility's roof structure was allayed by the fact that Square D's PowerBus 225 featured lighter, all-aluminum housing. Backing up the plan was the National Electrical Code, which states that cord drops can hang straight down from busway as long as they are supported every 8 ft. Using 100A tap units to plug into the busway would easily meet the power requirements of the 60A chambers.
Another reason to remove the raceway structure was that there was no way for Ball to monitor what the average load of a line was. Thus, it would be difficult to ascertain whether more equipment (like the testing chambers) could be added at any given time. Because busway has a single connection point to the main, it would be a simple task to meter each cell. The contractor also estimated it would be less expensive to shift to busway than meet the mandate with the raceway infrastructure.
The company was happy with the solution, except for its potential to interrupt workflow.
"We're a 24/7 operation," Ball says, "so we worked hard to mitigate the impact on the business." The job, comprising five 50-ft. cells, was completed in six weeks in April 2004. The original 20 testing chambers are still in use, and Solectron has increased that number since simply by adding more drops to the existing busway.
Busway now comprises 11 of 50 total cells in the facility, one of which was extended to 100 ft. last year. Busway has been added to six other cells, which took two weeks to complete, with no workflow disruptions. That section of busway is structurally anchored with aircraft cable.
Ball says the busway has increased Solectron's flexibility by "taking away the borders of the work cells and putting the power overhead. Now, there is nothing on the floor to obstruct us from putting a cell in any direction or fashion we want. Also, lead time for bringing on new products has dramatically decreased. Because we phase out old products and bring in new ones continuously, we have to set up quickly and get it going."
Cost savings have been realized due to the fact that existing busway drops can be set up quickly and easily for new equipment. Ball himself installs drops as needed to make process changes. He has also taught many of the facility's 500 employees to do the same. Occasionally, Ball has to buy more drops, but that, too, is less expensive than calling a contractor.
The busway has fit well with Solectron's Six Sigma and lean manufacturing philosophy. Ball says that during a recent Kaizen event, "We disconnected a line, picked it up, moved it to a different location, set it up and didn't miss a beat. We grabbed the drops we needed, took them with us, moved the line over and set it up. Within four hours," he says, "I can tear down a line and move it to another spot, with no electrical costs."
Ball says the next step is for the company to implement the same system in its sites around the world.
Schneider Electric United States
Use InfoLINK 180-60902-647 or Call 800-441-6180
Reprinted from IMPO Magazine
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|Title Annotation:||Focus On: Instrumentation and Controls|
|Publication:||Product Design & Development|
|Date:||Sep 1, 2006|
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