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Maxwell's Backup Capacitors Bridge Power Outages for Telecom, Other Critical Uses

Maxwell takes the "interrupt" out of "uninterruptible" and takes batteries out of the data center. PowerCache was recently named a Best Product of the Year by a mechanical design magazine. The product bridges momentary outages while a longer-term backup power source starts up. Ideal for medical, industrial, telecom and enterprise VoIP environments where continuous electric power is mission critical.

In a power outage, even the best backup power sources -- gensets, micro-turbines, fuel cells -- need at least a few seconds to start up and take over supplying power to a business. Those few seconds can be critical in medical, industrial, or telecom applications.

Mission critical
Voice over internet protocol (VoIP), for example, is a rapidly growing technology that connects telephone calls over the data network. When the data network becomes the voice network, reliability standards are considerably more stringent.

IP data networks can achieve 99.999 percent (five nines) reliability by thinking in duplicates -- redundant servers, redundant routers, redundant power supplies -- to make interruptions go almost unnoticed. But that's insufficient for voice communications, for one important reason.

Even if almost all downtime is eliminated, calls are dropped in the split-second switch from primary to failover systems. In other words, a brief power failure could disconnect all conversations in progress. And disconnections are bad for business, especially for a telecom carrier with thousands of customers.

Bridge power
The answer is to augment backup power with a bridge power source, such as batteries. But batteries have their drawbacks when it comes to maintenance and disposal. Maxwell Technologies, Inc. has a high-tech solution.

Instead of batteries, Maxwell's PowerCache product line is designed to provide maintenance-free alternatives for short-term bridge power by using ultracapacitors.

The 48-volt DC modules, rated at 1.6 or 2.3 kW, are powered by Maxwell's own 1,800- or 2,600-farad ultracapacitors. The 4U rack-mount modules fit most equipment racks. They behave like batteries in their discharge slope and output current. Lifetime cost is about the same as with lead-acid batteries.

Fuel cell companion technology
Maxwell's PowerCache was recently voted by the readers of Design News Magazine as one of the publication's 2004 "Product of the Year" award winners.

The modules are gaining acceptance as an adjunct to fuel cell backup systems, according to the magazine. Fuel cells run for long periods, but they have slow start-up times. Companies that use fuel cells for long-term outages can use ultracapacitors to bridge the 20-30 seconds it takes for the fuel cells to warm up.

Capacitors have been around since before Kodak discontinued the disposable flash bulb. The electronic components store power and discharge it on demand. Ultracapacitors are used in a variety of energy storage applications, including hybrid electric vehicles. Energy produced during braking is stored in the ultracapacitors, then used to power the vehicle's electric drive motors. Unlike batteries, ultracapacitors do not suffer cycle fatigue from repeated charging and discharging.

Maxwell is collaborating with manufacturers to integrate its backup modules with other backup power sources, such as generators. The company will be exhibiting at Global Windpower 2005, May 15-18 in Denver, Colorado.


we need buffer power during power failure for ac drives at high inertia load.
we want to stop it by use of inertial load power