Facilities Check List
Practical, step-by-step guides for the busy FM
September 1998
POWER LUNCH
Most facilities managers are familiar with the strong reactions of endusers who suddenly lose power during business operations. In manyinstances, end users remember the crisis when they are planning the nextrelocation and will ask for protection against another such outage. Inso doing, however, they often overcompensate and ask for more than theyneed. They may also adopt a reckless or naive approach to loading upcircuits; that is, they figure that as long as there’s a plug, there’scapacity, no matter what’s on the other end of the cord.
To alleviate these problems, we offer a few definitions of electricalpower supply that you may want to review with end users. You areencouraged to add your own price tags for each type of power supply,based on your own experience.
There are distinctions between redundant/backup, emergency,standby/fastrecovery, continuous, and clean power. But to end users, these terms mayall mean vaguely the same thing: I want my electricity available with nodisruptions in service. There are several different ways to provide thisservice, however, and several ways to recover if service is disrupted.The following sections will give your end users a menu of choices andhelp prevent them from asking for levels of service they do not reallyneed.
Redundant Power
Redundant power is an additional power source that complements theprimary source. It may consist of a second generator or an entireduplicate electrical service (a second electrical line, meter, and panelbox) from the utility company. Duplicate service normally permits usersto switch large portions of a building’s electrical load to another linewhile major equipment such as HVAC motors are being serviced, withoutshutting off power to the whole building.
In effect, redundant power capability requires you to buy most of theprimary components of an electrical power system (e.g., main line,transformers, breakers, and primary feeds) for a second system. Note,however, that most such configurations still require you to shut downall major equipment before switching to the redundant system and topower it back up after the switch is complete. Doing so requires a veryspecific procedure, well-trained personnel, advance notification of allbuilding occupants, and approval from the electrical utility company toensure that their network power grid and equipment will not be affected.
Emergency Power
Emergency power is power dedicated to operating the equipment needed toprotect life and safety during an emergency. It is not necessarilycontinuous. Many such systems are powered by on-site electric generatorsintended to be run for a few hours at most until main power can berestored. The engine is usually a diesel, similar to a car engine.Emergency loads are transferred in 20 to 120 seconds, after which thegenerator kicks in. However, during this gap between initial power lossand generator start-up, no power is available at the load. Because thecapacity of most generators is limited, only vital elements areincluded, such as the following:
- Egress lighting — stair and exit lights, corridor lights, elevatorlobby lights, and any lighting fixtures required for safe egress
- Fire detection, alarm, and suppression systems — including smokedetectors, autodialers to local fire and police departments,emergency-announcement systems, water pumps for sprinkler systems, andelectric locks
- Elevators, but usually only one cab, for use only by fire departmentpersonnel with special access keys
Standby Power
Standby power serves the same purpose as emergency power, but it isusually reserved for business operations — for example, to powercritical machinery. This power usually comes from separate, on-siteelectric generators, and their capacity is also limited. Thesegenerators can quickly restore power that has been disrupted, but theycannot in themselves prevent a loss of power.Standby power may kick in very quickly, even as fast as one or twoseconds. This is known as fast recovery power.
Continuous Power
Continuous power assures no interruption in service, even during a powerfailure. This type of power is almost a requirement for mainframe-basedcomputers and large networks. Continuity is usually provided by a UPS(uninterruptible power supply) system, but continuous does not meanindefinite. UPS systems are essentially a set of batteries that storeelectricity and are kept charged by power from the utility company. UPSpower comes from the downstream end (the battery) rather than from theutility itself. During a power outage, the batteries provide enoughtime, typically 15 minutes, to gracefully power down critical businessequipment such as computers and telecommunications equipment without aloss of data. But the more equipment loaded onto a UPS, the less timethe power supply will last. Standby power from an on-site generator canprovide more power to recharge the UPS and extend its operation to adegree, but this arrangement still does not ensure indefinite power.Even generators must be refueled at some point, and the generator willnot supply as much charging power as your primary electrical servicewill.
As you would expect, continuous power is the most convenient for theuser — and the most expensive to provide. UPS systems are anengineering specialty in their own right, and a very substantialinvestment is necessary if a full-blown, building-wide system isinstalled. Such systems are very large, very heavy, and veryheat-intensive.
If continuous power is not an option, a very practical stop-gapalternative exists: packaged, desktop, PC-sized, stand-alone UPS unitsthat can serve an individual PC, including a file server. Such unitscost about $200. A desktop UPS on a file server does not guaranteeintegrity of an entire network of PCs, only what is in the file server’smemory when the outage occurs. However, this system is better thannothing.
Clean Power
Clean power refers to circuits free of any electromagnetic interferenceor “noise.” To some extent, this condition may be obtained by installingspecial filters on individual circuits, running specially shielded cablein conduits, and steering clear of large electric motors and otherdevices that create strong electromagnetic fields when running conduits.However, in most modern offices, as much interference from harmonics iscreated by the electronic equipment we use as from electromagneticdisturbances elsewhere.
Armed with these definitions, the next time you see your customers,youcan truly enjoy a power lunch, in every sense of the term!
This check list is adapted from BOMI Institute’s Design, Operation, andMaintenance of Building Systems, Part II, a required course in theFMAand RPA designation programs.
