How Do Uninterruptible Power Supplies Work?

A sudden power failure and cause chaos in any commercial or business setting. Backup generators can restore at least some power to essential systems, but they take time to fire up. In the space between mains failure and backup power restoration, computers and other equipment stop, causing loss of data and disruptions to business. When large equipment is suddenly deprived of electricity, serious injuries and fatalities can result.

Uninterruptible power supplies bridge the gap between mains failure and backup power, giving you time to safely shut down equipment in those all-important first minutes of a power outage.

How do Uninterruptible Power Supplies Work?

An uninterruptible power supply, or UPS, stores power until needed. In the event of a mains failure, the UPS kicks in, providing power in as little as five milliseconds. The power provided by a UPS is limited, and will generally only last a few minutes. Limited though the power supply is, UPS power offers a window of opportunity in which to safely shut down equipment.

In addition to preventing catastrophic power loss, most uninterruptible power supplies can also handle voltage surges, spikes, and sags, and frequency differences.

Types of UPS

The answer to how uninterruptible power supplies work depends on the type of UPS installed. Uninterruptible power sources can be small enough to protect a single computer, or large enough to provide emergency power to entire buildings or data centers for a few minutes. Despite the broad range in operation specifications, uninterruptible power supplies generally come in three different types:

– Online uninterruptible power systems include constantly-charging batteries. A double-conversion method allows the battery to accept AC current, passing it through the battery as DC current before delivering it to protected equipment as DC.
– Line-Interactive UPS redirects the system’s DC current from charging the battery to supplying current when power fails.
– Standby / Offline UPS only kicks in if utility power fails. Less expensive than other forms of UPS, offline is best used for small loads below 1 kVA.

For larger loads, a variety of UPS known as dynamic uninterruptible power supplies may be used. A DUPS stores energy in a flywheel for use if power fails. DUPS are sometimes combined with diesel backup generators to ensure a continuous supply of power.

A UPS will not keep your facility running during an extended power outage, but the extra few minutes of power they supply offers a chance to keep your equipment, data, and staff protected.