Power From Above
Overhead access to power is ideal in ever-changing high-tech industrial facilities
In the realm of high-tech manufacturing, the "state" of a state-of-the-art product can be short, so when bringing a product to market, time is of the essence. In fact, by the time a new product hits the market, it is already in danger of becoming obsolete. Consequently, manufacturers require fast-track delivery for new facilities and rapid retrofits to accommodate constant changes in production lines.
One way for manufacturers of high-tech products to shift gears quickly is to power up their facilities with overhead busway. On the fast track
Speed is the name of the game, and this was a big challenge for the design team for the Sun Microsystems Assembly Testing Facility in Hillsboro, Ore. According to Scott Bange, program manager for project architect Jacobs Facilities—a division of Pasadena, Calif.-based Jacobs Engineering—the entire design team had to work closely together to make the tight schedule go, which was no simple task. "The project was especially complex from an electrical design perspective," says Bange, "which was furthered by the need to tailor design and construction solutions to Sun's schedule."
The 88,000-sq.-ft. facility, which assembles and tests network servers, had to be completed in six months, rather than the typical 12 to 18 months for a project of this type and size. In order to meet Sun's project schedule and to accommodate future expansion of building systems, the team at Interface Engineering, Milwaukie, Ore., had to approach the design of electrical, mechanical and lighting systems with the utmost flexibility. "Well into the project, Sun determined that the design [also had to] incorporate future needs to 'upsize' the system by as much as 25%," says Peter Lehmann, Sun's process engineering manager at the Hillsboro plant. "Interface was able to accommodate the request and still keep the project on time and within budget." Overhead electrical distribution
This meant producing a high-demand electrical-distribution system flexible enough to change configurations when a new product line is introduced. Compared with the 20- to 50-watts-per-sq.-ft. power densities typical of more conventional assembly plants, the Sun facility is designed to accommodate more than 150 watts per sq. ft.
With such a high power density, the electrical system had to be carefully coordinated in order to fit the system to the building structure, and with other building systems. The design called for a "drop down" system, with overhead distribution panelboards supplying power to 350 assembly bays using drop cords. The cords offer easy maintenance and flexibility to accommodate changes in manufacturing space requirements.
Designers decided on an elevated electrical infrastructure after carefully studying the load requirements of the facility. Compared with the traditional conduit and wire systems employed in older Sun facilities, the small profile of an overhead busway system not only conserves premium manufacturing floor space, but also uses less material than a conventional distribution system.
Further, the overhead distribution system cut costs in other ways. For example, power distribution was set at 480 volts, requiring step-down transformers that are located close to the load, greatly reducing distances for the distribution system. Also, rather than running hundreds of feet of wire from a remote panel, panelboards are directly above each manufacturing bay so that branch-circuit wiring only needs to drop a few feet.
In sum, the configuration provides the benefits of smaller space requirements for electrical equipment, reduced labor for installation and maximum flexibility with minimum maintenance.
Another state-of-the-art high-tech manufacturing plant that has made effective use of overhead electrical distribution is Honeywell's Cedar Creek facility in Olathe, Kan. The facility serves as headquarters for the Business and General Aviation Group of Honeywell's Avionics and Electronics Systems (AES) division, which makes various types of equipment for communication, navigation and surveillance.
Cedar Creek marks the first time since 1995 that Honeywell has moved into a completely new building. Work at the facility is based on a unique concept that brings personnel together in an integrated product team (IPT). "The key is having IPTs that unite engineers who design products, technicians who test them and associates who assemble them," explains Charles Kitterman, manager of facilities for the AES division.
With 2,300 employees—including some 500 assemblers and technicians—at the 560,000-sq.-ft. facility, Honeywell's intent is to use the integrated team approach to maximize communication, productivity and profitability. The approximately 750-ft.-long main plant floor is divided into four production areas, each home to one IPT. Kitterman explains that the company's commitment to the approach was a governing factor in selecting overhead power distribution and other systems that enable layout flexibility. The flexible factory
"The makeup and production responsibilities of the ITP groups often change as they strive for ultimate productivity," says Kitterman. "Our goal was to create an uncompromising flexible factory, so that we could rearrange a complete production cell in less than 24 hours."
Delivering both standard and 400-hertz current, the network of overhead fast-track busway specified on the project has outlets every 24 ft. Drop cords can be added wherever and whenever necessary. All outlets and drop cords have twist-and-lock connects, and six workstation benches can work off one power cord.
This system, says Kitterman, has greatly simplified both design and construction of the plant itself, as well as its manufacturing operations.
"The total design and installation effort for lighting and power supply was substantially reduced in office cubes, engineering cells, test centers and assembly workstations," says Kitterman. "Now, our electrical power delivery system is a simple question of 'where, and how many plugs?' With this overhead supply system, an entire production line can be reconfigured in 24 hours. Formerly, it took at least a week."
Before moving into Cedar Creek, Honeywell had tested the IPT approach at an existing facility, so the company saw the major benefit of an overhead distribution system: There would be no need for individual runs of conduit, which would require that wire be extended from a panelboard to each piece of equipment. As far as future expansion, the need for extra and redundant junction boxes at several locations along the conduit run would be eliminated. Versatile distribution
Both Sun Microsystems' Hillsboro plant and Honeywell's Cedar Creek facility have features in common that illustrate the product development and manufacturing needs of high-tech industry. Honeywell's Kitterman says it best: "A constant of the business is change. Expanding capacities for new products, reducing capacities of older, less-in-demand products and continually updating production methods to improve profitability are just a few of the reasons for change."
And because changing a conventional electrical distribution system of conduit and wire would be a large part of the cost of reconfiguring plants for new products, systems such as overhead fast-track busway can completely streamline production changeovers.
Lighting the Way to Energy Efficiency
Maximizing light levels and quality is a major design consideration for any manufacturing facility. Typically, high-intensity-discharge (HID) metal-halide lighting is used for high-tech industrial plants. But for the Sun Microsystems facility in Hillsboro, Ore., designers instead chose high-efficiency fluorescent luminaires. This resulted in higher quality color rendition, easier lumen maintenance and minimal shadowing.
To provide brighter than normal light levels in Sun's Hillsboro plant, designers also specified a highly reflective floor covering, which allowed an increase in the footcandle level at work surfaces. For higher lighting quality, lights were mounted at multiple elevations to provide ambient and task illumination that avoided obstruction from the power cords hanging from the ceiling.
Sun officials also needed lighting controls that could shut down or reduce lighting levels in areas not being used. Lighting designers from Interface Engineering, Milwaukie, Ore., met this need by dividing the manufacturing area into zones, with dual-level, programmable controls within each zone.
Peter Lehmann, process engineering manager at the Sun plant, praises the engineers for an innovative design. Even though Sun officials had no specifics in mind, "Interface was very adept at understanding the various elements that impact lighting, from skylights to the height of the ceiling to the color of the floor," says Lehmann, adding that the lighting has been termed "outstanding" by other computer manufacturers who have visited the site.
Cooling a Heavy Load
Intense electrical loads can, of course, have a major impact on mechanical design, as designers attempt to deal with the tremendous heat loads that are typical of manufacturing plants.
The Sun Microsystems facility in Hillsboro, Ore., makes and tests large network servers—about the size of a refrigerator—which operate at super-computer speeds and generate a considerable heat load. "When several of these units are being tested at full capacity, an enormous amount of heat is being generated," says Andy Frichtl, P.E., vice president of mechanical engineering at Milwaukee, Ore.-based Interface Engineering.
Interface, the consulting firm brought in to do the M/E work, had originally planned to use chillers, but instead, opted for a redundant system of 15 roof-top variable-air-volume (VAV) units, with two of the units serving as backups. Each 130-ton unit is equipped with economizer and power exhaust. The units are connected by a single large ductwork loop, with approximately 100 VAV boxes coming off the system.
As was the case for the electrical-distribution system, the mechanical design intent was to allow for rapid and efficient response as the manufacturing process changed. While manufacturing facilities are typically equipped with constant-air-volume systems, the VAV approach allows for division of the entire manufacturing floor into HVAC zones and operating efficiency at low loads.
Another state-of-the-art touch for this high-tech facility is the use of wireless sensors to control the HVAC system. "If a production line shuts down, we can throttle down in that area," says Frichtl.
Interface also used another fairly innovative solution to excessive heat loads: energy modeling. In their analysis of the facility, the engineers determined that the project design should reduce the amount of insulation in the building, to allow more heat to escape. Adding insulation to the building would actually increase energy use—a finding that led to the Oregon Dept. of Energy's revision of the state energy-code compliance program and also motivated the department to more closely consider how this type of manufacturing facility is required to comply with energy codes.
Interface also had to work closely with the city of Hillsboro to ensure the project conformed to various local code regulations. Peter Lehmann, process engineering manager at the Sun plant, explains, "The right questions were asked, and the answers incorporated into a workable, flexible design that met code requirements and our needs for possible future renovation of the plant."