What does it take to run Australia's largest Internet service provider (ISP) OzEmail? A powerful UPS system that uses a variety of units to protect the company's modems, servers, and other equipment.

Since users dial into more than 2000 modems at the main office in Sydney, OzEmail demands a steady supply of electricity to keep the network running. As well as its need to support Internet users, the recent introduction of value-added services like Virtual Private Networks and OzEmail Phone makes reliable power even more critical.

To protect its investment and eliminate the risk of downtime due to power interruptions, OzEmail installed a 100kVA UPS in its Sydney computer center. Using two battery cabinets that are each 0.8 m high and 1.5 m high, the UPS is 2 m high and 1.2 m wide. The UPS weighs 900kg, and each battery weighs around one ton. According to the manufacturer's service manager, a UPS of this size could power several houses with all their lights and utilities switched on for several hours.

Despite the UPS' large size, this unit would support OzEmail's system for just a half hour. Therefore, the company installed a backup diesel generator in the basement, which automatically takes over for the UPS in case of a long-term power failure.

While the Sydney office is OzEmail's largest facility, the company has also rolled out UPSs in its other Points of Presence (POPs) around the country. The Brisbane office also has a backup generator, while the 50kVA system installed in the Melbourne office can run the center for up to 4 hr; long enough for the company to wheel in a generator. In case of a power failure at any of OzEmail's 35 other POPs, a 6kVA UPS will keep the nodes running for at least 15 min. This gives the company enough time to reroute calls to another POP outside the affected area.

OzEmail's UPSs are online systems, which means they use incoming electricity to regenerate power. According to Peter Alford, provisioning manager with OzEmail, this capability is important for computer equipment sensitive to power fluctuations. Even though OzEmail is on the same power grid as the Royal North Shore Hospital; another heavy user of electricity; it's not uncommon for the company to get an occasional brownout.

With its power protection plan in place, OzEmail is now looking at ways to improve UPS management.

For a fast-growing company like OzEmail, keeping its UPSs ahead of this growth is paramount. Its first UPS, an 8kVA model that was upgradeable to 18kVA, was running at 105% capacity within six months of its installation. While OzEmail initially looked at installing a 30kVA system as a replacement, within a few weeks that requirement rose to 50kVA. By the time the company was ready to install the 50kVA system, continued growth necessitated a 100kVA model.