The central design of an uninterruptible power supply (UPS) system is categorized as its topology. Of the three primary UPS technologies available today — standby, line-interactive and online — each offers different performance characteristics and varying degrees of protection.
It’s important to recognize that not all UPSs are not created equal. Determining the best topology for your facility depends on a number of factors, including the level of reliability and availability required, as well as the type of equipment being protected and the overall application/environment.
Different types of UPS systems are appropriate for different uses, but no single UPS type is ideal for all applications. Consider the following topologies:
Also referred to as an off-line or passive system, standby topology provides the most basic type of UPS protection. Safeguarding connected equipment against a sag, surge or blackout, a standby UPS lets equipment run off of utility power until it detects one of those problems.
At that point, the UPS switches to the battery. Standby UPSs are best suited for less critical applications such as office environments, provided that the power supply is not subject to frequent disruptions.
The Benefits of Standby Technology
Benefits of a standby UPS system include:
- Cost-effective UPS system
- Provides continuous battery backup during a complete power failure
- Solid option for less-critical environments such as offices and point-of-sale applications
The Cons of Standby
While an attractive alternative from a cost perspective, the downside to standby UPS is that they do not buffer equipment against other power anomalies, and they must resort to batteries frequently, which can reduce battery run time and service life. You should also consider the following with a standby UPS system:
- It does not buffer equipment against other power anomalies
- It resorts to the battery frequently, which can reduce battery runtime and service life
- It is limited to small-scale UPS needs.
- The batteries have a short lifespan.
A UPS with line-interactive topology is designed to shield connected devices from power failures and sags like a standby model does, but it also provides protection against under- and over-voltage conditions.
Typically used to safeguard enterprise network and IT applications, the line-interactive UPS is controlled by a microprocessor that monitors the quality of incoming power and reacts to fluctuations. One of the biggest advantages of line-interactive topology is that it compensates for under-voltage and over-voltage circumstances without using the batteries.
These systems provide more protection than standby UPS, with better power conditioning and regulation that helps prolong battery life. Battery usage is lower than a standby UPS but still higher than an online model.
The Pros of Line-Interactive
Line-interactive systems have many pros, including:
- High reliability and efficiency
- Suitable for IT equipment like switches, servers and storage
- Available in various VA ratings and form factors to accommodate your environment
The Cons of Line-Interactive
Some of the downsides to line-interactive UPS systems include:
- The batteries cannot power equipment for very long
- They may not provide adequate protection for mission-critical and large industrial applications
An online or double-conversion UPS is designed to deliver continuous protection against all nine of the most common power problems, isolating equipment from any incoming power anomalies. Because the output voltage of an online UPS is entirely regenerated by a sequence of AC to DC conversion, followed by DC to AC conversion, it creates a supply of clean, consistent power regardless of any incoming instabilities.
An online UPS system switches to online double-conversion mode during moments of irregular power or disturbances, such as when AC input power varies from preset tolerances for line-interactive mode. If the input power exceeds rectifier tolerances or is completely lost, the UPS will rely on the battery to keep loads operating, then convert back to high-efficiency mode when it is safe.
Online UPSs are the best choice for critical applications or those involving highly sensitive equipment, such as data centers, communications hubs and other mission-critical installations where continuous, clean power is a business-critical requirement.
Pros of Online
Benefits of online UPS systems include:
- Ability to filter fast disturbances in power quality
- Ideal for sensitive loads and for businesses in areas with poor power quality
Cons of Online
Potential concerns with online UPS systems include:
- They have a complex design
- They may have a higher initial cost than other systems
How to Choose the Optimal UPS Topology
While all three UPS topologies outlined above meet the input voltage requirements for IT equipment, there are significant differences in both performance and demands on the battery. The following list of steps can help you learn how to choose the optimal UPS technology for your needs.
Step One: Know Your Business
Every business is different, and yours will have unique needs that affect the type of UPS system you choose. Larger businesses may need the extra power provided by line-interactive over standby systems. If your facility is in an environment with an unreliable utility supply, then an online system may be the most beneficial to you. You must also consider the complexities of your current electrical system to know which UPS system will work best for your needs.
Step Two: Know Your Options
Once you understand your own needs, it’s time to research your options. As you’ve learned above, each type of UPS system has its benefits and potential disadvantages. You’ll want to match your location, your electrical needs and your business as a whole with the right UPS system so you can stay up and running and protect your valuable equipment and assets.
Step Three: Partner With a Critical Power Equipment and Service Provider
Lastly, to achieve the optimal UPS topology for your organization, it is important to partner with a critical power equipment and service provider. Seek a company that has respect in the industry and recognition nationwide, as well as one who offers solutions to fit your power needs. It is also important that they be knowledgeable to answer all questions and help you make a final decision with confidence.
Explore UPS Systems and Services With Unified Power
If you need assistance determining the optimal topology for your environment, Unified Power can help you to properly identify and compare UPS topologies. Since our beginnings in 2011, we have grown into one of the largest critical power services companies in the nation. And thanks to our extensive experience serving a wide variety of industries, we can help you choose the correct topology for your business based on your unique needs. We have the UPS services you can count on.
Contact us today for more information about our equipment and maintenance services.
Page updated on February 22, 2022.