Electrical cable and conduit offers a reliable and proven way to get power where it needs to go, but that doesn’t mean it is always the best method. Busway can save space, while offering a less-expensive, more-flexible power distribution solution for applications where change and adaptation are important.
As is the case in many other industries, power generation facilities are perpetually short on capital, space, and time. Though economic conditions have improved in the years since the downturn, one thing that hasn’t changed is the fact that operators are continually challenged to maximize existing budgets and plant space, while identifying new efficiencies and minimizing operational costs.
One area many power facility and plant managers have identified as a way to increase efficiencies is in power distribution, specifically, the equipment used to distribute electricity throughout the facility. By investing in the right low-voltage distribution equipment, operators have been able to optimize the physical space within their facilities while also reducing energy costs and ensuring that power is being distributed with the utmost efficiency.
A good example of equipment that has emerged to deliver on this promise is busway, which is increasingly seen by many operators as an attractive alternative to traditional cable and conduit installations for a number of reasons. By using busway in place of cable and conduit, operators have been able to realize tangible savings in terms of capital, space, and installation time.
This article provides an overview of busway technology for power generation facility operators. In it, we look at the types of busway technology available, specific advantages of the technology over traditional cable and conduit solutions, and some key features to look for when implementing a busway solution in your facility.
A Busway Primer
Busway is a highly efficient method for distributing electrical power throughout a facility—particularly when it comes to loading or extending power from an existing distribution system. It comes in various shapes, sizes, and forms (Figure 1), but in general, all busway solutions feature the same core elements (Figure 2).
2. Sized to meet application needs. Busway components are constructed with a lightweight and durable, two-piece, aluminum-extruded housing. The nonventilated design prevents moisture and dust penetration. Courtesy: Eaton Corp.
First, there are the conductors, also known as busbars, which are solid bars of either copper or aluminum that transfer electrical current. Next, there’s the housing, the metal enclosure that contains the conductors. Finally, there is insulation, the key component that protects against electrical faults by separating conductors from one another and from the unit’s housing. Most busway products feature either air-insulated or epoxy-insulated designs.
Busway comes in two basic styles:
■ Feeder busway:Available in a wide variety of configurations, these are the main building blocks of a busway system and include both straight lengths as well as fittings, such as elbows, tees, and offsets.
■ Plug-in busway: Available in straight lengths only, these pieces feature the added ability to support one or more bus plugs at fixed positions. Bus plugs allow for power to be tapped off the busway system through overcurrent devices (such as breakers or fuses) to feed downstream loads easily.
Busway is especially attractive for power facilities, because they are typically packed with heavy-duty machinery and other electrical equipment. Historically, cable and conduit has been the primary method used to distribute power to this equipment. Often, the cable and conduit is embedded in concrete beneath the shop floor, making moves, additions, or changes more expensive and time-consuming. In contrast, busway can support new or rearranged systems easily by adding more pieces, relocating bus plugs, or replacing feeder segments with plug-in sections.
Benefits of Busway Over Cable and Conduit
Beyond the benefits already mentioned, the use of busway in lieu of cable and conduit offers several other advantages. They include:
■ Ease of installation. Installing cable and conduit is complex, labor-intensive work that only highly specialized electricians can perform. Busway, by contrast, is far simpler technology that most electricians with only rudimentary mechanical skills can assemble without expert help. Busway assembles quickly, with as few as one bolt per connection (Figure 3). Installers can add up to 10 feet of busway at a time as compared to routing multiple runs of conduit, and having to go back and pull cable through the pipes.
■ Reduced implementation cost.Paying specialized electricians for the hours of effort required to bend and route conduit is a costly proposition. Facilities that use busway can save money.
■ Space savings.Space is frequently at a premium in power facilities. Busway offers a compact technology relative to cable and conduit that leaves more room within the existing space for other, potentially revenue-generating uses. For example, a typical 2,000-amp service installed using cable and conduit requires up to 99 square inches of space versus less than 38 square inches using a busway solution.
■ Cost-effective adaptability.Once cable and conduit are in place, moving, expanding, and reconfiguring systems in response to growth or new requirements is both expensive and disruptive to daily operation. With busway, facilities installing new equipment can simply add new bus plugs to their existing busway, while companies that need to move equipment can quickly and easily reconfigure their existing busway or even replace feeder busway with plug-in busway, where required. This flexibility provides minimal interruption of service as compared to a traditional cable solution.
3. Easy installation. Busway fittings connect quickly and securely using a sandwich design and a torque-indicating bolt. Courtesy: Eaton Corp.
In all, these benefits can prove highly attractive to facility operators challenged to maximize available facility space while reducing capital expenditures, with a demonstrable benefit that helps improve the company’s bottom line.
Checklist: 10 Key Busway Features
Now that we’ve established some of the advantages of busway technology over cable and conduit, it’s important to understand the features to consider when choosing equipment for your facility. When looking to capitalize on busway’s considerable benefits, make sure to seek out products that feature the following attributes.
Certified Safety.At the bare minimum, any busway product worth using should be certified by Underwriters Laboratories, the Canadian Standards Association, or the International Electrotechnical Commission. Products that don’t meet these standards have not been tested for safe operation and may pose a risk to the facility if utilized.
Indoor and Outdoor Options. Depending on the needs of your facility, you’ll likely want busway to serve your needs both inside and outside the plant buildings. Reputable busway technology manufacturers typically offer options for both types of applications, so make sure to seek out those that do.
Wide Variety of Current Ratings. Varying applications require varying current ratings, which can shift over time as the facility grows and needs for power distribution change. The best busway solutions support any current rating the facility might need, both now and in the future.
High Fault Current Ratings. To protect sensitive electrical equipment, busway must be capable of handling the available fault current rating a given power distribution system is capable of throwing at it.
Broad Range of Plug Options. Look for product families whose bus plugs offer breaker, fusible switch, contactor, and starter options for every requirement, as well as multiple surge protection and metering alternatives.
Flexible Configuration Options.Variety is equally important when it comes to power distribution options, so be sure to choose busway products capable of handling both single-phase and three-phase power, with or without a neutral bar, or even with a 200% neutral option. Selecting products that support integral, internal, and isolated grounding options is also critical.
Ease of Installation.All busway products are easier to install than cable and conduit, but best-in-class offerings further simplify deployment by providing thoughtful extras like alignment pins that prevent operators from installing bus plugs out of rotation, and clearly labeled stickers that illustrate where segments connect.
Alternative Options for Connecting Directly to Other Electrical Equipment.Most busway manufacturers require facilities and contractors to connect other products like group metering and panelboards via cable runs between bus plugs and distribution equipment. The most sophisticated busway solutions, however, save money and floor space while shortening installation times by allowing companies to connect group metering and panelboards directly into a nearby busway segment instead.
ENERGY STAR and LEED Certification. Facilities certified under the Leadership in Energy and Environmental Design (LEED) standard for environmentally sustainable construction are often eligible for tax breaks and other financial incentives, so look for busway products that qualify for LEED credits. And using busway bearing a SMaRT certification can qualify facilities for additional utility rebates, while reducing operating expenses by lowering power bills.
Comprehensive Services and Support.Finally, while busway is an intuitive, largely do-it-yourself technology, users sometimes require planning and implementation assistance. Make sure to buy only from vendors with the experience and resources to offer expert support and services when needed (such as busway measurement services, final field fit services, and commissioning).
Reflect on Options
Though cable and conduit has been the default choice for distributing power to electrical equipment for many years, busway offers an extensive list of practical and financial advantages for power facility operators. Those plants looking to simplify power distribution and increase agility while saving money and conserving space should take a close look at carefully designed and equipped busway solutions with the features, support, and capabilities to meet their unique and evolving needs. ■
—Steve Lovell is a product line manager for busway at Eaton Corp.