Reliability of backup power systems, called uninterruptible power supplies (UPS), hinges on proper installation, regular preventative maintenance and well-being checks. Without them, you may as well start working on your resume. Like other parts of the electrical system, the UPS must be deployed with regard to safe practices in specification and use, and that means strict adherence to codes and standards. In addition to the UPS equipment, there are the lead-acid or nickel cadmium (NiCd) batteries, and those, too—with their stored electrical energy—must be handled and deployed properly.
As power requirements increase in every vertical market, contractors are focusing on quality as it equates to longevity for the installation and lower total cost of ownership. According to independent research conducted in 2006 for Electrical Contractor magazine by Renaissance Research & Consulting, New York, some 56 percent of reader-respondents consistently performed power quality work as part of their business. Part of that focus includes backup power.
There rarely is enough power to accomplish some of the monumental information technology and service tasks at a facility. Data centers are huge users. You can expect this trend to continue. In fact, more than 40 percent of data center customers report power demand outstripping the supply, according to Morten
Stoevring, general manager of American Power Conversion (APC) in Kolding, Denmark. They need more power to handle the increasingly detailed and complex tasks that run on the network as well as other facility and energy management functions. In addition, according to the Report to Congress on Server and Data Center Energy Efficiency released by the U.S. Environmental Protection Agency in August 2007, the energy consumption of servers and data centers has doubled in the past five years and is expected to almost double again in the next five years to more than 100 billion kilowatt hours (kWh), costing about $7.4 billion annually.
That means more backup generators and mission-critical power sources will keep facilities running around the clock, even in the event of an outage. A UPS installation is a crucial part of the equation, and it has to be reliable and readily available in an instant with little or no down time. We all are familiar with backup power for lighting, but in the case of a data center, it keeps the network up and running.
Data centers are not the only super users of power. Security command centers, automated plants, hospitals and acute care centers, institutions, and other operational parts of a facility count on quality power and immediate backup.
Backup power equipment for emergency or load management comes in the form of diesel and gas generators, transfer switches and paralleling switchgear. The end-use or application determines what standards the equipment falls under and how it is to be installed, serviced and maintained. In addition, routine maintenance guidelines from the manufacturer always are included either with or on the equipment.
Ultimately, backup power creates its own footprint at the plant or premises. It can be distributed where it will be used or operate in separate equipment rooms. A single-line diagram should be drawn and updated with UPS and related battery sources.
Knowledge is the electrical contractor’s best friend when it comes to safety. The Technical Liaison Department of Thomas & Betts Corp., Memphis, Tenn., recently released a practical guide to electrical safety that provides updated information on practices to follow for a safe working environment in “Electrical Safety in the Workplace.” The safety-training program (see www.tnb.com) offered these tips:
No energy = no electrical injury
Identify all sources of electrical
Interrupt the load current
Conduct a visual inspection
Apply lockout/tagout devices
Use rated voltage detectors
Ground system components
Regular maintenance is approached with care. Often, the power cannot be shut down, and the load end never powers off. That is where hot swappable comes in. The module is de-energized, pulled out and replaced with another, while redundant modules keep the load operational.
“It’s possible for a 80 [kilovolt-ampere] kVA system to have 10 or so modules and to unplug and replace them one at a time and still maintain 80 kVA throughout the facility and satisfy requirements for zero downtime when mandated,” said Steve McCluer, senior applications engineer, American Power Conversion, West Kingston, R.I. “This technique also satisfies requirements for safety because a person with minimal training can do that. Another important safety parameter is to be able to provide service with a minimal use of tools. Two key sources of power failure are the system being shut down unexpectedly during maintenance and using tools to service the system.”
Best practices, McCluer said, are the way to prevent or mitigate potential UPS problems and hazards.
Safety goes beyond the UPS. Other precautions center on the batteries for these units and their stored energy.
Batteries look benign, but “there’s enough power to kick you off your feet,” McCluer said. “There are many ampere hours stored in there, and people who work with batteries need to know what they are doing. For example, lead-acid batteries have the potential to have things go badly if overcharged or not maintained or not used with regards to best practices.
If a separate room is used to store the batteries—again, dependent on what type of application—there are physical construction requirements for those locations. When you have a battery room, then you have installation and maintenance concerns as well as distribution issues to get the DC out of the room. You have to have a ‘disconnect’ for DC; most are rated for AC. And, as you increase the distance of the batteries from the UPS, you have to be aware that the voltage drop can be significant, and this has to be figured in the overall equation,” he said.
You would not build a facility without proper backup in the way of generators and uninterruptible power supplies. Follow best practices in the installation, selection and maintenance so the UPS can swing instantly into action. EC
O’MARA is the president of DLO Communications in Park Ridge, Ill., specializing in low-voltage. She can be reached at 847.384.1916 or firstname.lastname@example.org.