This UPS buyer’s guide was developed to answer some of the basic questions organizations have about UPS systems.

What is a UPS?

A UPS, or uninterruptible power supply, is a device which provides emergency power to IT equipment when the primary power source is interrupted or fails.

Whether your IT equipment is in an IDF room or a large data center, a UPS is an important part of your availability, disaster recovery, and business continuity plans.

1 HR of data center downtime can cost an organization more than a half-million dollars.

The average cost of a data center outage is $740,357.

Why Does My IT Infrastructure Need a UPS?

The impact from technology failure and downtime can be significant and far reaching: customers can’t place orders online, employees can’t work, airplanes can’t fly, and the reliability of your brand is at stake.

Without a UPS, power failures can cause significant business interruption:

• System failure
• Equipment damage
• Data loss
• And, for healthcare entities, potential HIPAA violations

Common Features of UPS Systems

Energy Storage Systems

Providing backup power to critical loads requires a UPS and an energy storage solution like batteries or flywheels.

Energy storage solutions Include:

Batteries

• VRLA (valve-regulated lead-acid) batteries are sometimes called sealed lead-acid (SLA), gel cell, or maintenance free battery. VRLA batteries are rechargeable and are considered low-maintenance, but still require regular cleaning and testing.
• Lithium Ion Batteries are a viable alternative to VRLA technologies. Lithium-ion batteries have a significantly longer life span, require less maintenance and service, and have a much smaller footprint – allowing floor space to be dedicated cooling requirements, resulting in lower operating costs.
• Flywheels are a battery-less solution. They deploy kinetic energy (created by an internal rotating mass), which can be utilized to provide power. Flywheels can be connected in parallel to increase power and runtime. For those who wish to lessen their dependency on batteries, and who do not require longer runtimes, flywheels may be a better option.

Power Protection

Electricity flowing through power lines can cause irregularities such as swells, sags, spikes, and other power anomalies. In environments with voltage issues, frequently switching to battery can drain reserve power and ultimately shortens UPS battery life. Some line interactive UPS systems can detect power issues and correct them without using battery power.

Additionally, most UPS devices shield sensitive equipment from damaging power surges which may damage equipment, and cause data loss.

Monitoring Solutions

Battery Monitoring Systems

Battery monitoring systems fit inside or on top of your UPS cabinet and identify potential problems such as cell voltage, overall string voltage, current, and temperature.

If the batteries exceed set thresholds, IT managers can take the proactive action of replacing the bad battery before it affects the others in the string, or before it causes complete string failure.

Monitoring Software

Monitoring software like Trellis or SiteScan helps identify battery problems before they impact operations.

You can rely on up-to-date, comprehensive data about devices and equipment locations, current capacities and power usage to confidently implement installs and changes without compromising availability.

Power Supply

Selecting an appropriate UPS power-distribution system is essential to ensure availability of critical applications. UPS systems are categorized into two power distribution types:

UPS Topology

The types of uninterruptible power supply systems are defined by how power moves through the unit:

Standby or Off-Line System

The AC input is filtered through the unit and past the transfer switch at the output point.

When an input power failure happens, the battery and the inverter (converts the battery’s DC power to AC) are activated and power the output.

Line-Interactive System

The inverter becomes part of the output and is always on. The inverter can operate in reverse to charge the battery while AC input is normal, and switch to battery power when input fails, which provides filtering and voltage regulation.

On-Line Double Conversion

For higher voltage applications, the inverter is the primary power path instead of the AC input. Used with above 10kVA, the AC input is converted to DC power to charge the battery, and then flows through the inverter, which converts it back to AC for output.

This eliminates any spikes or dips from the input, but lowers efficiency and increases heat generation as well as wear on components.

UPS Applications

UPS models come in a variety of specifications to provide the right fit for applications from desktop workstations to enterprise data centers. To understand the basic categories of UPS equipment, let’s look at some common server and desktop UPS models.

Desktop UPS

Desktop UPS models supply power to the computer and monitor in the event of a power outage. Many models are rated on the length of time they will provide battery power. Most desktop UPSs provide enough time to save work and properly shut down the CPU. Power output for desktop UPS equipment ranges from 250 VA – 3000 VA.