Choosing a UPS System 101: The Fundamentals (2024)

February 19, 2018by CyberPower

Choosing a UPS System 101: The Fundamentals (1)
New to the world of uninterruptible power supply (UPS) systems? Consider this UPS buying guide your introduction to the basic concepts behind UPS Systems and which type will work best for your requirements.

What is a UPS System?
A UPS, at its most basic, is a battery backup power system that supplies power long enough for equipment to properly shut down when utility power fails. It helps prevent loss of data and minimizes the stress a hard shutdown causes on your electronic equipment.

The UPS is also a surge protector that protects connected devices from power problems, like surges or abnormal voltages, which can damage, reduce lifespan, or affect performance of electronic equipment and devices.

Why do I need a UPS System?
In case of a blackout, the UPS switches immediately over to battery power to provide a continuous power source for the length of the battery. Battery life can vary by system and depends on how much power you use. The battery backup gives you time to power down sensitive equipment, servers, or even video game consoles without loss of data or progress. Different UPS systems also provide certain levels of protection for other power problems that arise.

What types of UPS Systems are there?
UPS systems have three different topologies, or categories, based on what type of power protection you need. The three topologies are Standby, Line-Interactive, and Double-Conversion.

What types of power problems do I have?
Many people are aware of only one type of power problem: a blackout. This is when the power goes out and stays out for a few seconds up to a few days. But, many more common power problems exist.

What are common power problems?
Below are definitions of common power problems. If you would like to learn more about power problems, please read our blog: Preventing Common Power Problems.
For now, let’s define possible power problems you might experience:

  • Surge – A brief, but intense, spike in electricity commonly caused by lightning. Surges can damage and destroy electronics, and the intense “spike in electricity” or spike in voltage and current harms circuit boards and components.
  • Blackout – A power outage lasting anywhere from seconds to days. These are most commonly caused by severe weather, utility power shortages, accidents, and power grid failures.
  • Brownout – An intentional or unintentional drop in voltage for an extended period of time. In emergency conditions, power companies may lower the voltage of your electricity to reduce strained resources and avoid a total blackout.
  • Voltage Sags – A sag is also a type of under voltage, but, unlike a brownout, it’s sudden and brief.
  • Over Voltage – Occurs when incoming voltage is higher than normal and lasts longer than a surge but not high enough to be classified as a surge or spike.
  • Frequency Noise – Also known as line noise, frequency noise can disrupt or degrade the performance of a circuit by injecting abnormalities into the system.
  • Frequency Variation – Not a common problem when power supplies are stable, but it can occur when using generators and power frequency fluctuates more than desired.
  • Harmonic Distortion – A departure from the ideal electrical signal on a given power source.

What type of UPS Do I Need?
Make a list of your most common power problems from the definitions above, and use the chart below to pick which topology solves your problems.

Choosing a UPS System 101: The Fundamentals (2)

How Big Does My UPS Need to Be?

In order to make your UPS run properly, your UPS has to be large enough to support all of the equipment plugged into it. You will need to find the UPS capacity. Capacity is how much power a UPS system can provide (measured in Watts). The higher the capacity, the more electronic equipment, and devices it can support. To find the UPS capacity, you will need to calculate the load. TheLoad is the combined amount of power each of the devices use.

To identify the load, make an equipment list, including the total watts each piece of equipment requires to run properly. Include all of the devices the UPS will need to support. If a piece of equipment has a redundant power supply, only count the wattage of ONE power supply.

If you are unsure how many watts your equipment requires, consult the manufacturer or power supply specifications in the user manual.

Here is an example of an equipment list to verify the load:

Choosing a UPS System 101: The Fundamentals (3)

Once you have calculated your load, count the number of power cords you want to connect to the UPS. Your UPS system will need to have enough outlets to cover the number of power cords.

How much time do I want electricity once the power goes out?
You have already decided your UPS’ topology and what size it needs to be. Now, you need to think about what you would like to do with the battery power when a power problem occurs. Would you like to focus on shutting down all of your connected devices safely? Do you want to keep your DVR and TV running during the power problem? Do you want to finish the section of the video game you are on or just save where you are at?

You must now determine runtime. Runtime is the number of minutes a UPS system can support the attached devices with electricity during a blackout. The minimum runtime is the time you need to complete proper equipment shutdown.

When shopping for runtime, you will be looking at the length of time the batteries in the UPS can support equipment through power outages when utility power is unavailable. Keep in mind the number of watts supported affects runtime: the smaller the wattage load connected, the longer the batteries will last. The larger the wattage load, the shorter the runtime will be.

To determine runtime, we want to look for a range. Begin with the number of minutes it will take to perform complete device shutdown and then build an acceptable range of runtimes. The broader the range, the more UPS system choices you will have.

Choosing a UPS System 101: The Fundamentals (4)

Do I need sine wave output from my UPS?
Utility power supplies electricity in the form of sine wave alternating current. When the UPS is in normal mode, it passes the same electrical sine wave to your connected devices. If the UPS switches to operate in battery mode, it either produces sine wave or simulated sine wave electricity to power your electronics.

Here is an illustration of a sine wave and a simulated sine wave.

Choosing a UPS System 101: The Fundamentals (5)

You will notice the simulated sine wave output has a power gap at each cycle. Sometimes this power gap may cause stress in the power supply in sensitive electronics, harming them.

You will need a UPS with sine wave technology if you want to plug-in the following:

  • Apple iMac Computers
  • Computers and Equipment that are Energy Star® or 80 PLUS® efficient systems using Active PFC power supplies.

Electronic equipment with Active PFC power supplies may shut down unexpectedly when using a UPS with simulated sine wave output, resulting in data loss or equipment damage. UPS systems that deliver sine wave output prevent unexpected shutdowns and damaging electronic stress.

If you need help determining whether a device uses Active PFC circuits, contact the device manufacturer.

What do I want my UPS to look like?
UPS systems have form factors. The form factor of a UPS indicates the shape and size of its housing. The most common 3 types are:
Desktop or compact
Tower or mini-tower

When choosing the form factor, the main consideration is where you are going to use it. A desktop or compact UPS can hide under a desk, unnoticed. A tower or mini-tower will have a pleasant aesthetic design making it an option to sit on top of a desk or table. A rackmount UPS works well in server rooms.

Where do I pick out my UPS system?
Now that you have made a list of what you need in your UPS system. Visit our Battery Backup Selector to help you narrow down which of CyberPower’s UPS systems will fit your needs. If you need some guidance, feel free to contact our UPS systems experts or toll-free at 1 (877) 297-6937.

If you’re interested in a more in-depth look at selecting UPS systems, come back soon for our blog: Choosing a UPS System 201: Power Audits

Battery Backup Selector

Choosing a UPS System 101: The Fundamentals (2024)


How do I determine what UPS I need? ›

When sizing a UPS for your specific requirements, the power factor matters most. Generally, your UPS should have an Output Watt Capacity 20-25% higher than the total power drawn by any attached equipment.

What are the specifications that should be considered when buying an UPS? ›

Buying the right UPS: Key considerations
  • Determine the size of the load that needs UPS protection, and, hence, the capacity of the UPS. ...
  • Assess the required UPS runtime for critical devices and applications. ...
  • Determine the number of outlets required. ...
  • Consider UPS installation requirements.

How do I choose UPS? ›

The Basic Requirements

The UPS must be able to handle the total power load of the equipment that requires protection. It is recommended that the output watt capacity of the UPS is 20 - 30% higher than the total wattage of its connected equipment.

What are the basics of UPS system? ›

5.1 UPS systems

A system of supplying power by converting AC input (utility power) to DC and reconverting it to stable AC by the inverter while constantly charging the batteries. Supplies power without momentary power breaks in the event of a power outage.

How long will a 1500VA UPS last? ›

7 /120V = 1.26A @120V for 1 Hour which needs to be derated further because of battery condition and the lower limit for input voltage on the inverter. 1500VA is the maximum output (voltage x current) of the unit. At 1500VA the backup would last 216 VA/H/1550VA = . 144 HR or 8 Minutes.

How to calculate UPS requirements? ›

To size the UPS:
  1. List all the equipment and devices you want the UPS to protect.
  2. List the amps and volts for each device. ...
  3. Multiply amps by volts to determine VoltAmps (VA). ...
  4. Multiply the VA by the number of pieces of equipment to get the VA subtotals.
  5. Add the VA subtotals together to get the total power requirement.
Nov 11, 2022

How to decide which UPS to buy? ›

Selecting a UPS System by Capacity/Runtime

No matter what type of UPS system you buy, you'll need to make sure it has enough capacity to support the wattage of the devices you plug into it, as well as enough battery runtime to shut down safely. It's important to account for the number of plugs your UPS has as well.

How long will a 1000W UPS last? ›

For example, if you've got a 1,000-watt UPS with 125-minutes of standby time, your backup should last for 8-hours with no power outage.

How do you size UPS for home use? ›

Determine both the voltage and the amperage for each device. It should be included in the device's documentation or listed on its nameplate. Multiply the voltage by the amperage to calculate each device's volt-amp (VA) rating, then add all VA ratings together to determine the total VA necessary for your UPS.

How to select UPS for server? ›

UPS Buying Guide: How to Choose a UPS for Your Server Rack
  1. Footprint / space requirements.
  2. Battery runtime.
  3. Lifespan of the battery.
  4. Battery recharge time and cycle life.
  5. Power, cooling, and other operating costs.
  6. Energy usage.
  7. Operational overhead.
Mar 26, 2024

What should I know about an uninterruptible power supply? ›

UPS units are critical for protecting vulnerable (and often expensive) hardware components from physical or memory-based damage when they're suddenly disconnected from the main power circuit. Even in the case of a total power-off event mid-transfer, a UPS can ensure vital data isn't lost.

What size UPS for TV and router? ›

1200 VA / 720 Watt inverter with 1 battery will power a TV, DSTV, Computer a few lamps and cell phone charger for up to 4 hours. 2400 VA / 1440 Watt with 2 batteries will power 3 or 4 TV's or 3 or 4 computers, DSTV a few lamps, cell phone chargers and an Internet router for up to 4 hours.

What are the three types of UPS systems? ›

The three major types of UPS system configurations are online double conversion, line-interactive and offline (also called standby and battery backup).

What is the general arrangement of UPS system? ›

The UPS consists of a battery charger, an inverter, output transformer, a set of batteries, control circuits and transient/ EMI filters. The on-line UPS provides a conditioned output voltage when the power is on and charges the battery through the battery charger.

What capacity UPS do I need? ›

For example, if the device you would like backup power for has a label that says the input power is 120 volts, 3 amps, multiply 120 volts by 3 amps to get the wattage (360 watts). Then try to find a battery backup UPS with a capacity rating of at least 20% more than your device's wattage.

How do I calculate UPS package size? ›

For each measurement, start at the longest point, rounding each measurement to the nearest whole number. Multiply the package length (longest side of the package) by the width by the height. The result is the cubic size in inches.

How to select UPS for office? ›

Choose a UPS with voltage input that is equivalent to the input power of the equipment. The applicable UPS voltage differs by country, so it is vital to select the UPS with the corresponding voltage level. Which UPS topology is the most suitable? Select the topology based on power needs.

How long will a 1000VA UPS last? ›

What is the typical runtime at full load of a 1000VA UPS system? From 4 minutes to 30 minutes on internal UPS batteries, depending on the UPS. Extra UPS battery packs can be added to increase this. 5.

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