UPS Buying Guide

1. Determine the size of the load that needs UPS protection, and, hence, the capacity of the UPS

Step one is assessing which IT or electronic devices warrant UPS battery backup protection and the power required by each device so that you can calculate the required UPS capacity. The power consumption of IT servers, computers and workstations, and networking equipment are obvious places to start. Still, you might also want to include other devices that are critical to the day-to-day operation of the business, e.g., point of sale equipment and security systems, among others. Assess what applications each component supports and how the loss of that application will affect your organization.

For each device to be connected to the UPS, determine the power consumption (watts) of that device.  Power consumption can typically be obtained from the equipment nameplate or manufacturer documentation.

The required UPS capacity is the sum of the power consumption of the devices to be connected to the UPS.
 

2. Assess the required UPS runtime for critical devices and applications

Step 2 is to determine the desired UPS runtime for continued operation in case of a power failure.

If you have a generator for extended backup power, the required runtime of the UPS may only be a few minutes (~5 minutes) to safely start-up and transition to the generator.

On the other hand, your primary goal may be to have enough runtime (~5 to 10 minutes) to safely shutdown servers and workstations to avoid any data loss or corruption.

Or, for some applications, such as networks and Internet access (very critical these days), you may want to have 1 to 2 hours of runtime to be able to ride through most outages.

Keep in mind that, in general, the more equipment you connect to a single UPS, the shorter its overall runtime will be.  An alternative may be to use separate UPS’ for certain applications.
 

3. Determine the number of outlets required

Add up the number of devices that you need the UPS to support, and make sure the UPS has enough outlets to meet your immediate needs, and also leave some room for growth.

Alternatively, you can use a power distribution unit (PDU) to provide additional outlets, but be careful not to overload the UPS.

Some UPS models also include outlets that only support surge protection.  These outlets do not provide battery backup. Make sure you understand the features of the UPS you are buying and that it has enough battery backup outlets to meet your needs.
 

4. Consider UPS installation requirements

UPSs come in a variety of sizes and form-factors. Tower models are standalone units that sit on the floor, or a desk or shelf, and often backup desktop computers, servers, and routers in an office environment.

Rack-mount UPS models are typically designed to fit in a standard 19-inch IT rack along with other IT equipment.  Rack-mount UPSs vary in size, and their height is measured by how many vertical slots it occupies in the rack. Each space is known as a “U” and measures 1.75 inches.

UPSs designed to use lithium-ion batteries tend to be smaller and lighter than similar models that use traditional lead-acid batteries, enabling you to fit more backup power capacity in the same space – or the same capacity in a smaller space.

Remote Monitoring and Management

UPSs with built-in network ports or support for network management cards (NMCs) can be monitored and managed remotely. This is especially important for UPSs installed in branch offices or edge locations with limited or no IT staff on site.  In this case, a centralized IT or facilities group can monitor the status of all UPSs and be notified of issues such as batteries that need replacement. NMCs may also support environmental sensors, enabling the remote monitoring of conditions such as temperature and humidity.
  

Remote UPS Outlet Control

Some UPS models include outlets or outlet groups that can be managed remotely, including the ability to monitor energy usage, and cycle power or turn off these outlets or outlet groups. This can enable someone in a remote operation center to reboot a hung server or network switch, for example.
  

LCD Control Panel

From a local perspective, an LCD screen on the UPS can display useful information such as battery health and power conditions, and facilitate local management and control of the UPS.
  

User Replaceable Batteries

No battery lasts forever, and UPS batteries are no exception. But given that the main purpose of a UPS is to ensure uptime, UPS battery replacement must be a quick and easy process.  Consider models that feature a removable panel that makes it easy for the user to replace the batteries, rather than having to call in a service technician.

Lithium-ion Batteries

Lithium-ion batteries are becoming more common in UPSs and for a good reason. They can easily last twice as long as traditional lead-acid batteries yet weigh far less and take up less space. They also support faster charging and more charge/discharge cycles. In many cases, the lower total cost of ownership (TCO) of a UPS with lithium-ion batteries will make them well worth the additional up-front cost. (To learn more, visit our Lithium-ion Batteries page.)
  

Extended Runtime

Some UPS models support external battery packs that can provide extended runtime beyond what a UPS’s internal battery offers, enabling users to get potentially hours of battery backup time for critical loads.
  

ECO-mode for Energy Savings

UPS Eco-mode seeks to save energy by bypassing the voltage regulation and/or energy conversion processes of the UPS if it determines that the utility input power is of good quality, to save energy.