How to engineer manufacturing, industrial buildings: Electrical and power systems
Manufacturing and industrial facilities can be particularly complex projects, involving large facilities containing behemoth machinery, hazardous chemicals, and a range of other concerns. The draw on the local power system is a key factor for electrical engineers to consider.
- C. Erik Larson, PE, LEED AP BD+C, Principal, Industrial Systems, Wood Harbinger, Bellevue, Wash.
- Ronald R. Regan, PE, Principal, Triad Consulting Engineers, Morris Plains, N.J.
- John Schlagetter, NCARB, PMP, CSI, CCS, CCCA, LEED Green Associate, Senior Architect, Process Plus, Cincinnati
- Wallace Sims, SET, NICET Fire Alarm Level IV, Lead Life Safety Engineer, CH2M Hill, Portland, Ore.
CSE: Describe some recent electrical/power system challenges you encountered when designing a new building or working in an existing building.
Regan: A client acquired an existing 20-story high-rise with the intent of duplicating an existing data center environment he has in another state with more than 250,000 sq ft of white space. The building’s power system, while extensive and capable, was no match for the anticipated load. Compounding the fact was that the facility sits on the Hudson River and was a victim of Hurricane Sandy flooding. The first issue was negotiating with the utility for two new 38 kV class feeders, and the second was to fit 38 kV class switchgear in one half of the space normally required (all the room left in the approved electrical vault). Our firm worked hand-in-hand with a custom switchgear manufacturer to design a one-of-a-kind, high fault duty rated compact lineup that needed to be approved by both the city inspector and the utility. Working as a team to solve the problem, the city, the utility, and our firm produced a viable solution. This design is now being considered by the utility for Hurricane Sandy victims that must move their substations from below grade or at grade to higher floor locations. The more compact and lighter switchgear helps make such a migration more acceptable with fewer structural modifications needed.
Larson: When working with the University of Oregon, it needed its new systems to connect directly to the university’s grid rather than the local public utility district (PUD) grid. This required a very complex modeling program to ensure smooth operation and uninterrupted service. Eighty-nine potential switching configurations were established, either manually prompted by the university or by the automatic controls. The challenge was determining the appropriate data needed for proper simulation for each of those 89 configurations, as well as how to test without damaging the systems or equipment. This resulted in an extensive matrix that systematically kept track of the various possibilities. Based on the modeling results, the university was assured that the installation could work reliably.
CSE: How do you balance the need for reliable power with the desire for efficiency and sustainability?
Regan: As more of our projects seek to be LEED certified and the pressure is on to deliver efficient/sustainable projects, yet with high reliability, we must perform the needed balancing act. Interestingly, some thought processes for achieving efficiency goals lead to better reliability. Electrically, we see decisions to purchase more expensive high-efficient equipment such as transformers, HVAC equipment, and variable frequency drive (VFD) packages to save energy and decrease carbon footprint, and then there is the realization that this more costly equipment is actually more robust and reliable and, thus, achieves our reliability goals, too.
Larson: At the University of Oregon, we were able to use a cogeneration system that had the capability to increase power reliability without compromising the efficiency or sustainability of the system. The combined cycle system could be operated in parallel with the utility or as an independent grid or island, separate from the utility as a micro-grid. By operating in an island configuration, Wood Harbinger was able to mitigate any extended utility outage, thus maintaining campus operations. Because of the increased efficiency, the amount of fossil fuels released was dramatically reduced, and the university received a savings of more than $700,000.
CSE: What low- and medium-voltage power challenges have you overcome?
Larson: The project at the University of Oregon was a complex medium-voltage power solution. The new medium-voltage switchgear is a 4-bus ring configuration. Bus A was fed from the utility and connected to half of the campus feeders, Bus B also has a separate utility feed, 7.5 MW of cogeneration, and is connected to the other half of the campus; it is connected to Bus A via a tiebreaker. Bus G has three 2.275 MW diesel generators and room for a fourth, and it is connected to Bus A and Bus S via tiebreakers. Bus S feeds all the standby power feeders on campus, and is connected to Bus B and Bus G via a tiebreaker. The new chiller plant and upgrades to the boiler plant required a new service from the utility; this required the building to be on a new 60 MW double-ended substation for the university. Wood Harbinger worked with the university, the local utility, the contractor, the switchgear manufacturer, the diesel generator manufacturer, and the cogeneration equipment manufacturer to ensure that all the components would be able to be paralleled together and would correctly reconfigure the system and switchgear, without interrupting power to the campus, if any of the 89 scenarios happened.
Regan: On overseas projects, especially in developing countries, we often run into the problem of unskilled workers in a high-tech world. Some of these countries limit ex-patriot supervision and entrance into the country. On a project in the Middle East, the concept of duct banks, high-voltage splicing, and cable pulling was too much for the assigned (by the government) local contractor to grasp and execute. As they were very capable of digging trenches, we worked with a U.S. cable manufacturer to deliver “oversized reels” of 15 kV metal-clad armored cable, “cable in flexible conduit,” to our local contractor. We were able to run from switchgear to all terminals with no manholes, no cable pulling, and no splicing. All terminations, as there was a manageable amount, were handled by our ex-pat team of supervisors/splicers.
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