The Power to Produce - Proactive planning for power quality and reliability.

Oct. 5, 2001
SPECIAL REPORT: Power Quality (Part 1)

The need for power quality in commercial facilities has grown exponentially in the past decade. From a modest desktop computer to comprehensive server networks, from an electric drip coffee pot to sophisticated video conferencing equipment, it's a given that commercial buildings need to be well-wired to provide constant, reliable power for today's electronic world.

And in the tenants' minds, building owners and facilities managers take the immediate blame when the lights dim and the computer system crashes.

"Tenants are rapidly moving toward a widespread expectation that good power quality and reliability are a given," says Larry Vanderburgh, director of training and instruction at BOMI Institute, Arnold, MD. "Everyone knows computer systems are part of office life and work, and that computers need quality power and reliability. They naturally extend this logic to building owners and expect them to provide reliable power to keep their computer systems and networks running."

It's no wonder why commercial landlords are moving in this direction. Once left in the realm of electrical engineers, such terms as uninterruptible power supplies, surge arrestors, and harmonics are rolling from the tongues of owners and managers. Power quality has come to the forefront of building management, and most facilities professionals strive to ensure as reliable a power network as they can muster.

To achieve any sense of power quality, you must take your building's system over and above what current electrical codes require, experts say.

"Building codes usually deal with the minimums driven by safety," notes Brooke Stauffer, director of codes and standards for the National Electrical Contractors Association (NECA), Bethesda, MD. "The National Electric Code is a minimum safety code. It designs a system that is safe but that might not be the highest-performing electrical system. Building owners need to think about what additional level of quality or reliability needs to be built in beyond the basic code requirements."

Power quality means power without spikes or wide voltage swings, minimal outages, no brownouts, and no harmonic distortion. A power supplier can assure all but the last one, according to Vanderburgh. But harmonic distortion - waveform fluctuations caused by the power supplies of certain electrical or electronic equipment - is a function of a building's occupants.

Although a perfect power system with 100-percent reliability cannot be obtained realistically, today's technology provides solutions that can get facilities near this lofty goal.

There are distinctions between redundant/backup, emergency, standby/fast recovery, continuous, and clean power. But to tenants, these terms mean the same thing: ways to keep their electricity available and operational with no service disruptions.

The first consideration is ensuring a building has sufficient power to satisfy the electrical requirements for the technology and electrical loads it supports.

You need to ensure that this service not only is appropriate for current and projected needs but also if there is sufficient physical breaker space in the facility's panels to handle increased number of circuits. Failure to do so could result in electrical overloads.

Most electrical problems are "glitches" - small sags or surges or other relatively minor fluctuations that do not cause outages but can affect the performance of electronic equipment. Online uninterruptible power systems, such as surge protection, smooth out those glitches and keep things running smoothly.

In the case of outages - brownouts or blackouts - more sophisticated measures generally are needed. "If power outages cannot be tolerated, a standby power system, such as a generator, can be installed," says Neal Boothe, an engineer with GRG Vanderweil Engineers Inc. in Maitland, FL. "If outages due to maintenance of the generator cannot be tolerated, parallel generators can be provided. If momentary outages between the loss of utility power and startup of the generator cannot be tolerated, an uninterruptible power source (UPS) may be added. A UPS system may even be double-ended and/or paralleled to provide continuous power while another UPS is down for maintenance."

You can add layer upon layer of sophistication to your facility's power reliability system if you choose. But, as Boothe cautions, with each layer of added protection comes another layer of costs.

"A facility owner must weigh his power reliability concerns against his bottom line," he says. "The facility's risk of power failures and outages should be a driving force in evaluating the level of electrical reliability."

Simply put, there is no right answer to how much redundancy is enough when it comes to reliable power.

Subodh A. Kumar, an IFMA fellow and president of Chartered Facility Management Group Inc., Pasadena, CA, suggests working with a qualified consultant with expertise in power quality issues for the specific type of facility in question.

"Lately we've heard a lot about N+1 and N+2 facilities requiring multiple levels of redundancy for facilities that are expected to operate 24 hours, seven days a week," he says. "A business case analysis [should be used] to determine the cost-benefit ratio of such investments."

Gregory Massey, PE, a Kansas City-based electrical engineer who has experience in both public and commercial facilities, says using engineering judgment in making fundamental design decisions, such as installing separate grounding conductors to supplement metallic raceways, is the first step in ensuring good power quality.

Many high-rise buildings, for example, have two incoming electrical lines. When two or more electrical lines are in-phase, they can be designed to supply the load at the same time. This is commonly referred to as a "spot network." If one line is lost, the other line(s) seamlessly pick up the load without perceptible loss of power. And it works.

"An 18-story office building in Kansas City, for example, has four utility feeders networked together and uses UPS systems for some of its critical clients," Massey says. "That building blew a transformer, and nobody within the building knew it happened. The utility company came knocking on the door four days later, saying it traced a dead fault to the building. When that transformer blew, the other three lines picked up the load, and things operated as usual. The power to that building has never been interrupted. It would take a complete blackout in downtown Kansas City to knock that building off-line."

The benefits of uninterruptible and standby power lie in helping building owners manage their risks. This risk may involve the loss of crucial data, such as a data center; the loss of revenue and production, such as a manufacturing environment; or a threat to public and/or patient safety, such as healthcare facilities.

Facilities professionals must manage the risk of power outages vs. the cost of providing the level of standby and/or uninterruptible power necessary. It often comes down to weighing the benefits of increasing the electrical system's reliability against the cost of the increased systems and making an informed decision based on the evidence.

Because most facilities professionals are generalists and expertise in electrical and power issues tends not to be a core competency, retaining an experienced power quality consultant can help facilities professionals ensure that a building's systems are optimally designed and specified. A business impact analysis of power quality can clarify exactly what tenant needs the building must fulfill and guide development of the proper power reliability system.

"The facility's risk of power failures and outages should be a driving force in evaluating the reasonable level of electrical reliability," says Vanderweil Engineers' Boothe. "There is no one right answer to this question. The electrical system that may be cost prohibitive and excessive for one owner may not provide the protection another owner desperately needs."

Robin Suttell, based in Cleveland, is a frequent contributing editor to Buildings and BI-Buildings Interiors magazines.

Voice your opinion!

To join the conversation, and become an exclusive member of Buildings, create an account today!

Sponsored Recommendations