By William Atkinson
A few short decades ago, if the power went out in your office building, you could probably live with it for a short time as a minor inconvenience. Office staff could still use the telephones, the accountant could continue to work on the books, and the engineers could continue drafting their designs.
All of that has changed.
We are now so dependent on computers and other office machines that if the power goes down, the office grinds to a halt, meaning lost productivity, lost business and lost revenue.
“Businesses are becoming more dependent on continuous power, especially as they become increasingly dependent on servers,” says Matt Johnson, director of business development for Gaia Power Technologies, New York, N.Y., which manufactures backup power systems. “These days, even most small businesses have servers. Their businesses will stop working when that server stops working.”
Certainly precasters can’t expect to keep the heavy electrical equipment running during power outages unless they purchase extremely large and expensive backup power generators. However, with some relatively inexpensive and easily installed backup power systems, they can keep their offices – and all of the equipment in those offices – running.
There are three general types of backup power: portable generators, pad-mounted generators and battery backup units.
Portable gas, diesel or propane generators can be purchased at any hardware store. These are inappropriate for office use, though, for at least three reasons. First, they must be run in outdoor areas because of the fumes and resultant danger of asphyxiation. Second, they lack sufficient power to run anything but the smallest pieces of equipment. Third, they generate “dirty power,” which can quickly destroy sensitive equipment such as computers.
Large, outside-mounted “pad” generators can put out anywhere between 7 kilowatt-hours and 125 kwh of power. These are fueled by either the office’s natural gas service or, if no natural gas is available (such as in the case of all-electric service), serviced with LP gas that is delivered by truck. These units connect directly to selected circuits on the breaker box. If and when power goes out, the generator immediately begins providing power to the circuits that are connected. A business may elect to have such a generator power office equipment but not the central heating or air conditioning system, for example, as they alone can pull up to 15 kwh of power. Of course, the more you’re willing to spend, the larger a generator you can install and the more circuits you will be able to power.
While these units are certainly acceptable for backup power, they do have some drawbacks. First, if natural gas service is disrupted (such as may occur during a strong earthquake), the units cannot run. Alternately, if the unit is fueled by a propane tank, these tanks can explode. In fact, most local codes require that anything larger than a small 125-gallon “pony tank” must be sited a certain distance from the building. In addition, if the outage lasts more than two or three days, the tank will need to be refilled. If the unit is running because of a natural disaster, it may be difficult or impossible to arrange for the local gas company to make a delivery of propane to refill the tank.
Battery backup units
The third option is indoor battery units. These use sealed (marine, AGM or gel-cell) batteries that are linked with an inverter to change the DC power from the batteries into AC power for office use.
“Battery units are energy storage devices,” says Norm Cotrona, president of Alta Power Corp., Shelton, Conn., which manufactures battery backup units. “Unlike generators, they do not generate electricity. Battery backup systems are only as good as the energy that is already stored in the batteries.”
Battery units range in size from very small (1 or 2 kwh) to large (15 or 20 kwh). The benefits are that they are used indoors, release no fumes and are relatively safe. One drawback is that, in most cases, when the batteries run out of juice, you are without power. Some units, though, have battery recharging options, either through vehicle batteries or portable generators.
Battery units come in two types. The first type, like the outdoor pad-mounted propane generators, consists of a large battery bank inside the building and are hard-wired to the breaker box. When the power goes out, these units kick on immediately. The second type consists of smaller units that remain plugged into AC wall outlets to stay charged. Once the power goes out, you wheel the unit to where you want it, then simply plug the equipment into the battery units.
If you select a pad-mounted, fueled generator or a hard-wired battery bank, an electrician needs to manage the installation. If you select a portable battery unit, this is not necessary.
Hard-wired battery-based, extended-run backup power units offer high-quality power as well as surge protection, and can provide many days of backup power, says Johnson. The “purity” of the power from the inverters is between pure sine wave and modified sine wave – not as pure as utility service, but better than portable fuel generators.
“Units weigh between 1,000 and 2,000 pounds and are permanently installed by an electrician,” he adds. The batteries in the unit can be recharged using portable generators, solar panels or wind turbines.
“When working with a new customer, the first thing we would look at is the power requirements,” explains Cotrona. “The customer provides us with information on the types of equipment they want to run.” Although each application has different requirements, portable battery backup units typically are plugged into AC-power wall plugs. Once an outage occurs, any piece of equipment plugged into it will begin to run, using the power stored in the batteries.
What about “power purity”? The inexpensive backup power systems available from auto supplies and other retail stores use high-frequency inverters, which can damage sensitive office equipment, says Dave Straub, president of Alternative Power Systems, Woodstock, Ga. He adds that hybrid inverters, which are between pure sine wave and modified sine wave, are safe for sensitive equipment. Even utility grid power isn’t always pure, as is the case when power spikes or power sags occur. “Most sensitive electrical equipment has protection for these problems, though,” he says.
Are such units worth the cost? “You may only have a couple of power outages each year,” says Straub, “but if you are able to stay in business, these units can pay for themselves the first time they are used.”
William Atkinson, Carterville, Ill., is a freelance writer who covers business and safety issues.