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An uninterruptible power supply (UPS) plays a key role in providing temporary emergency power to computer and electronic equipment, a server, network or data center in the case of a blackout, thunderstorm or any other incident that causes a power loss. With a reliable UPS system, you can avoid damage to expensive equipment and loss of critical data.

UPS systems fall into three main categories: standby/offline, line-interactive and online double conversion. These three categories are defined by how the unit handles power flowing through it. The type of UPS that is right for you can depend on cost and the type of equipment you plan to protect.

Read on to learn more about the characteristics of the three types of UPS systems and how they can help protect your customers' equipment and data.

1. Standby/offline UPS

Best suited for desktop computers, home networks, printers, scanners and other similar equipment, a standby UPS provides protection against power surges and offers battery backup if there is a power outage. Under normal conditions, the standby UPS receives power from an AC outlet.

When the unit senses an abnormality in the flow of power — such as a surge or sag — or a complete power failure, it switches to battery mode. The switch to battery mode gives enough runtime for someone to save their work in progress and conduct a proper shutdown of their equipment.

These units provide the most basic protection out of the three categories and tend to be the most affordable.

2. Line interactive UPS

A line interactive UPS offers more protection than a standby UPS but at a relatively cost-efficient price point.

Line interactive UPS systems provide battery backup like an offline/standby UPS while also providing electrical power conditioning, which eliminates voltage fluctuations. This feature allows the unit to maintain safe voltage levels without using battery power, offering effective protection against brownouts and common light sags and surges.

If the unit senses a large spike or sag, or if there is a complete power failure, then it will switch to the battery backup mode. The line interactive UPS is best suited for desktop computers, network workstations, and AV equipment as well as network server racks and office networks.

3. Online double conversion UPS

If you're looking for the highest reliability and best protection from spikes, sags, power distortions and complete power failure, the online double conversion UPS is the most applicable choice. This type of UPS system continuously converts incoming AC power into DC then back to clean AC.

Because of this, there is no transfer time when switching from direct power to battery backup mode, which is why it provides connected equipment much higher protection against power spikes, dips or complete failures. This type of UPS system is designed to protect critical equipment in data centers, server rooms and intensive care units and is the most expensive option.

Standby/Offline Line Interactive Online Double Conversion
Best Suited For Desktop computers, home networks, printers, scanners and similar equipment Desktop computers, network workstations, AV equipment, network server racks and office networks Critical equipment in data centers, server rooms and intensive care units
Provides Battery Backup
Surge Protection
Brownout Protection
Provides Power Conditioning Full-time
No Transfer Time When Switching to Battery Power

Other helpful UPS tips

  • Consider the equipment you plan to protect. If protecting home electronics or computer equipment — such as a desktop or home network — basic protection from a standby UPS will likely be sufficient. If you're looking to protect equipment in a data center or server room, you'll need to choose more reliable protection from an online double conversion UPS.
  • Think about overall cost and budget for your project. If not protecting critical equipment or data, keep in mind the cost of the UPS system you plan to choose versus the cost of the equipment you will be protecting. In many cases, it might be important to use a higher level of protection. In other situations, basic protection could be an adequate and cost-effective option.
  • Understand your customer's needs. Be sure to ask your customers questions about what type of equipment they have and if they need to protect sensitive or critical data. Discuss the protection levels different UPS systems offer to help decide on what will provide the best fit for their budget and needs.