This buying guide will help you:
- Understand what a UPS system is and its key features
- Learn the questions to ask before you select a UPS system
- Compare the different types of UPS systems
An Uninterruptible Power Supply, also called a UPS system or UPS battery backup, protects connected equipment from power problems and provides battery backup power during outages. Some UPS systems also regulate abnormal voltages.
Which Type of UPS Should I Buy?
Top 3 Features of a UPS System
All UPS systems have two critical functions: to provide battery backup power and to protect equipment from power surges and line noise interference. Some types of UPS systems also regulate incoming voltage for even more protection.
As long as the electricity stays on, the UPS system passes utility power to the devices connected to its outlets, keeps its internal battery fully charged and protects devices from power problems, such as surges and abnormal voltages.
If the power goes out, the UPS system provides connected devices with backup power from its internal battery. During an extended blackout, battery backup gives you an opportunity to properly shut down equipment, like computers and DVRs, that can lose data when turned off unexpectedly.
Built-in surge protection and noise filtering shields equipment from destructive transient voltages and electromagnetic (EMI/RFI) line noise.
In locations with chronic voltage problems, frequent switching to battery drains reserve power and shortens battery life.
Line-interactive UPS systems provide Automatic Voltage Regulation (AVR) to solve this problem. The UPS detects when input voltage is out of bounds and corrects it without using battery power. All line-interactive UPS systems provide brownout protection. Select models also provide overvoltage protection.
On-line UPS systems use double-conversion technology to provide the highest level of power protection. The UPS continually converts incoming AC power into filtered DC power, and then resynthesizes it back into AC power with a pure sine wave.
How to Buy a UPS: 7 Questions to Answer
When you buy a UPS, the most important considerations are total electrical load and runtime. The UPS must be capable of supplying enough power to keep your essential equipment running for the duration of the outage (or until an alternative source of power, such as a generator, is available).
1How much power does your equipment require?
Make sure that the UPS can handle the total electrical load (power draw) of the equipment that you want to connect to it. To estimate power capacity requirements, add the wattage of each device. Refer to the equipment nameplate or the manufacturer's documentation to find the wattage. If output is listed in amps, multiply by the AC voltage to estimate wattage.
Key Point: Choose a UPS with an output watt capacity 20-25% higher than the total wattage of the devices you want to connect. You can use our Load Calculator to determine your total load.
2How much backup runtime do you need?
Runtime is the number of minutes that the UPS is able to provide battery backup power to connected equipment when utility power fails. As power capacity increases, runtime decreases. Select UPS systems accept external battery packs to extend runtime during a blackout.
Key Point: Adding more equipment to the UPS will result in a shorter runtime.
3What is the voltage of your power source?
In North America, the voltage used to power servers and networking equipment is typically 120V or 208/240V. Europe and Asia typically provide 230V power.
Key Point: Be sure that the UPS input plug matches the receptacles of your input power source.
4How many receptacles do you need?
Make sure you have more outlets than the number you need to ensure room for future growth. Most rack-mount UPS applications will require a Power Distribution Unit (PDU) to accommodate extra equipment plugs.
Key Point: Select UPS systems have some surge-only outlets that do not supply battery backup, so make sure the UPS you choose has enough battery-protected outlets for your mission-critical equipment.
5Do you need pure sine wave output?
Pure Sine Wave power is required by some devices, such as computers with active Power Factor Correction (PFC) power supplies. Pure sine wave power also helps prevent other devices from overheating, malfunctioning or failing prematurely.
Key Point: UPS systems with Pure Sine Wave output provide superior compatibility with active PFC power supplies and other sensitive equipment, such as networking hardware and high-end audio/video components.
6Do you require data line surge protection?
Data and audio/video lines connected to your equipment represent an unlocked "back door," allowing surges to enter and damage or destroy sensitive electronic components.
Key Point: Select UPS models have RJ11 jacks, RJ45 jacks or coaxial connectors to protect equipment against surges on connected phone, network or coaxial lines.
7Where do you plan to install the UPS system?
UPS systems come in a variety of sizes and form factors.
- Desktop models are compact to fit on a desk, protecting computers and peripherals.
- Tower models stand upright on the ground or on a desk/shelf. They are typically used in network workstations or desktop computer applications.
- Rack-mount models can be mounted in standard 19" rack enclosures and require anywhere from 1U to 14U (U=rack space). They are typically used in server and networking applications.
Key Point: Make sure the UPS you choose has the form factor you need and will fit your space.
UPS Features Explained
Most UPS systems have built-in USB, serial (DB9), and/or contact closure communication ports that enable power management and automatic unattended shutdown.
Multifunction LCD Control Panel
An LCD screen may allow access to the advanced features of the UPS system without a computer. It can display helpful information like input voltage or battery capacity. (Some UPS systems with multiple LEDs also show this information, though less precisely.) The LCD typically has a backlight. If you plan to use the UPS system in a darkened home theater setting, make sure you can dim the backlight to minimize distractions.
Most models feature a removable panel for internal battery replacement. Tripp Lite offers a complete line of replaceable battery cartridges.
Select UPS systems have lithium iron phosphate (LiFePO4) batteries. Compared to lead-acid batteries, lithium iron phosphate batteries offer longer life, more cycles and faster charging to 100% capacity.
Select UPS systems accept external battery packs to extend runtime during a blackout.
Larger UPS systems typically have built-in cooling fans, which may affect the noise level of your environment during operation.
Remote Power Management
Network management cards turn any network/server UPS equipped with a network card slot into a managed device on the network. You can remotely monitor energy usage and reboot unresponsive equipment from anywhere. The optional network card allows comprehensive management via SNMP, Web, SSH or telnet. The card has an Ethernet port, allowing you to access advanced monitoring, control and notification features over the network without directly connecting the UPS to a computer. The card also supports one or more optional sensors for remote temperature, humidity and contact closure monitoring. Some network/server UPS systems include a pre-installed network card.
Do you need uptime during maintenance? Hot-Swap UPS Systems have a detachable PDU with a manual bypass switch that enables live UPS repair or replacement.
UPS Features Comparison Chart
FEATURES BY UPS TYPE
Line-Interactive for Desktops
Line-Interactive for Networks
|TYPICAL USE||Desktop computers, home networks||Desktop computers, network workstations and audio/video equipment||Network server racks, office networks||Mission-critical equipment in data centers and server rooms|
Emergency backup power for utility power outages
Protection against power surges or spikes
Maintains safe voltage levels without using battery power
Keeps overvoltages from damaging connected equipment without using battery power
Pure Sine Wave Output
Perfect power for sensitive electronics
On-Line, Double-Conversion Operation
Zero transfer time to battery
- All Models in this Product Family have this feature.
- Some Models in this Product Family have this feature.
- This Product Family does not have this feature.
UPS & Battery Recycling
We recommend you recycle old UPS systems and batteries to support a cleaner, more sustainable environment.
Glossary of UPS Terms
- Alternating Current (AC)
- A type of current that alternates from positive to negative at regular intervals. AC is the standard type of current used in electrical distribution systems by utility power companies due to the ease that it travels through cabling. Electrical wall sockets in nearly all structures served with utility power provide AC power.
- Ampere (Amp) (A)
- The unit of measure for electrical current.
- Apparent Power
- The load power as expressed in VA or KVA (e.g. 3,000 VA UPS, 20 kVA UPS System). This value is usually greater than real power due to circuit reactance.
- A group of cells connected in such a way that more current and/or voltage is delivered than from one cell. See Direct Current
- An AC power failure lasting anywhere from a few cycles to several hours or even days in duration.
- Short for circuit breaker. See Circuit Breaker
- Common term for undervoltage, taken from the coloration of filament style light bulbs during undervoltage conditions. See Undervoltage
- Charge Voltage
- The voltage that must be applied to storage batteries to maintain their maximum charge.
- Circuit Breaker
- A resettable device that responds to a preset level of excess flow by opening the circuit, thereby preventing damage to circuit elements.
- Clamp Voltage
- The maximum voltage allowed on an electrical circuit due to the operation of protective devices (surge protection). When line voltage exceeds the clamp voltage of the suppression components, the signal is diverted to the ground. The clamping voltage of a product is important because it tells a user at what point the surge protector "kicks in" or "clamps" a surge or noise related condition. Most North American AC surge suppression products have a clamping voltage of around 140 VAC (Internationl products clamp at around 300 VAC). Outside phone line protectors commonly have a clamping voltage of around 260V and most 10-100BT-network protectors have a clamping voltage near 7.5V.
- Common Mode Voltage
- The voltage present when measuring between neutral to ground.
- The flow of electricity in a circuit as expressed in amperes (amps).
- Cycles per Second
- This term describes the frequency of alternating current. Frequency is measured in "hertz (Hz)," which is synonymous with cycles per second.
- See Direct Current
- Decibel (dB)
- The standard unit of expressing the loss or gain of electrical power in a circuit.
- A short duration brownout condition, usually in response to inductive loads starting and stopping. See Brownout
- Direct Current (DC)
- A type of electricity where current flows in one direction, without reversal such as from a battery.
- Any deviation from the normal sine wave for an AC quantity. Alternating waveforms with a square or rectangular waveshape carry some amount of distortion. Typically, a good AC supply waveform will carry 5% THD (total harmonic distortion) content or less. See Harmonics, Total Harmonic Distortion
- Double-Conversion UPS
- See On-Line Double-Conversion UPS
- Dropout Voltage
- The voltage at which a device fails to operate properly and/or safely. Most computer systems will reboot, reset, or place save data at risk when line voltage falls below approximately 95-100 VAC.
- Ratio of output energy to input energy for a device. Often refers to the amount of energy lost in the form of heat during DC to AC operation.
- Electrical Interference (EMI, RFI, etc.)
- These are acronyms for four common types of electrical interference: Electromagnetic Interference (EMI), Radio Frequency Interference (RFI), Electromagnetic Pulse (EMP), and Electrostatic Discharge (ESD). All four types are unwanted signals common in noisy electrical environments.
- Electromagnetic Interference. See Electrical Interference
- Energy Absorption
- The amount of electrical energy absorbed by a device measured in joules (J).
- Energy that is fed from the output of a circuit back to its input.
- An electronic device that blocks the passage of certain frequencies while allowing other frequencies to pass.
- Common formulas necessary to properly size UPS products. [Amps = Volt Amps / Nominal Voltage] [Volt Amps = Nominal Volts x Amps] [Watts = Volt Amps x Power Factor]
- The number of cycles (oscillation positive and negative) completed in one second. In North America, utility power completes 60 cycles per second or 60 Hz.
- A device that automatically self-destructs when the current passing through exceeds the rated value of the fuse.
- Combination of a motor driving an electrical generator. Gas generator systems are frequently used in conjunction with electronic UPS systems for very long-term operation during extended power outages. They are frequently employed in healthcare, emergency and other highly critical applications. Generators typically require 1-3 minutes to startup before being able to provide reliable output. Certain types of less sophisticated generators may have a problem with frequency regulation.
- A conducting connection, whether intentional or accidental, between an electrical circuit and the earth, or to some conducting body that serves in place of earth. See Ground Rod
- Ground Loop
- The condition of having two or more ground references in a common system. When two or more grounds have a potential difference between them, current can flow. This flow of current is a new circuit or loop which can interfere with the normal operation of the system.
- Hardwire Protectors
- Products requiring installation by a qualified electrician who connects individual wires according to NEC (National Electrical Code) Standards. Some hardwire power strips and large UPS systems require hardwire input and output connections.
- A frequency that is a multiple of the fundamental frequency. For example, 120 Hz is the second harmonic of 60 Hz, 180 Hz is the third harmonic, etc.
- Harmonic Distortion
- Excessive harmonic content that distorts the normal sinusoidal waveform is harmonic distortion.
- Hertz (Hz)
- Refers to the frequency of alternating cycles in an AC waveform per second. In North America, utility power is provided at 60 Hz. In Europe and most of the rest of the world, utility power is provided at 50 Hz. See Frequency Deviation
- Hot Swappable Battery
- Refers to the feature that allows the battery of a UPS to be changed (due to age or defect), without taking the unit (and its attached load) out of service.
- Abbreviation for hertz. See Hertz
- Measured in ohms, impedance is the total opposition to current flow in a circuit where alternating current is flowing.
- Inductive Load
- Electrical load whose current waveform lags the voltage waveform (thus having a lagging power factor). Some inductive loads such as electric motors have a large startup current requirement. See Inrush Current
- Inrush Current
- The initial surge of a current into a load before it attains normal operating condition. Certain types of loads, such as motors, compressors, air conditioners, power tools and other large loads require 2-5 times the energy on startup than they do continuously. Incandescent, filament style light bulbs tend to dim briefly when a motorized load, like a window air conditioner, pulls a high degree of inrush current on startup.
- The subassembly of a UPS that converts DC power to AC power.
- Isolated Filter Bank
- A unique feature of the Isobar surge protector that prevents noise created by equipment plugged into one bank of an Isobar from affecting a device plugged into a separate bank on the same Isobar.
- Isolation Transformer
- A transformer used to reduce or eliminate noise and create the equivalent of a dedicated or isolated ground circuit. These transformers are included in many 3kVA and larger UPS systems. Standalone isolation transformers serve the function of removing common mode noise. See Common Mode Voltage
- Measure of electrical energy. Often used to rate a surge protector's ability to absorb energy.
- Abbreviation for kilovolt amperes. A unit of measure of apparent power. (1 kVA = 1000 VA) See VA
- Abbreviation for kilowatt (a unit of measure of real power). 1 kW = 1000 Watts. See Watt
- Line Interactive UPS
- A UPS design based on a standby system with enhancements. Line Interactive systems still switch to battery power when a blackout occurs, but instead of also switching to battery power when brownouts or overvoltages occur, a tap switching voltage regulation circuit activates to maintain usable power at the output continuously, without consuming battery power. The main benefit is that connected equipment can run straight through extended brownouts or overvoltages without draining the battery. Line Interactive systems are widely considered mid-level products between basic standby UPS systems and higher end on-line UPS systems. See On-Line Double-Conversion UPS, Standby UPS and Tap Switching
- The electrical device that uses power supplied by the source.
- One of the conductors of a 3-phase wye system. The neutral wire carries the entire current of a single-phase 120V circuit and the resultant current in a three-phase system that is unbalanced.
- Unwanted electrical signals that produce undesirable effects in the circuits of the control systems in which they occur. See Electrical Interference
- Nominal Voltage
- A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage classes (120 VAC, 208/240 VAC, 12 VDC, 24 VDC, and 48 VDC). For example, a 120V wall socket will rarely measure exactly 120 volts. The nominal (or named) voltage of 120V actually refers to a range of usable voltages centered around 120 volts. See CBEMA Curve
- Non-Linear Load
- Electrical load that draws current discontinuously or whose impedance varies throughout the cycle of the input AC voltage waveform. It typically involves electronic devices that pull a great deal of startup current. Some examples are motors, heating elements, air conditioners, power tools, compressors, etc. See Inductive Load & Non-Linear Load
- Normal Mode Voltage
- A voltage that appears between or among active circuit conductors. A 120 VAC-wall receptacle should yield full nominal voltage between hot and neutral line connections. See Common Mode
- Off-Line UPS
- Another term for Standby UPS. See Standby UPS
- On-Line Double-Conversion UPS
- A high-end UPS design where output power is completely regenerated and passed to connected equipment with zero transfer time between line and battery power. Incoming AC power is converted to DC and then re-converted back to AC by a continuous duty inverter system. The dual conversion process completely regenerates the power flowing through an on line UPS, completely removing all surges, spikes, noise and other irregularities, to provide pure, frequency regulated sine wave output at all times. On-line, double-conversion UPS systems are widely considered the best possible type of UPS available. See Standby UPS and Line-Interactive UPS
- Orderly Shutdown
- Sequential shutdown procedure used on a computer system to prevent damage to the system or unwanted actions by any of the system's units. For example, a computer typically requires an orderly shutdown to preserve data integrity.
- A long-term loss of voltage resulting from a localized utility failure.
- When used to describe a specific type of extended variation, overvoltage refers to a voltage having a value of at least 10% above the nominal voltage for any lasting period of time. This occurrence may last a few seconds, several hours, or become a continuous condition depending on the site and prevailing conditions. Overvoltage differs from a surge because it's a condition of less severe voltage levels that lasts at minimum for several cycles.
- Peak Voltage
- A measurement of an AC waveform of the highest peak-to-peak voltage present on the waveform. A properly synthesized 120V nominal AC waveform will have a peak voltage (also known as "peak to peak" voltage) of approximately 170 volts.
- A term used to describe the timing between two or more events tied to the same frequency.
- Point of Use
- As applied to power protection, point of use protectors are placed near equipment, as opposed to placement at branch circuits or utility power entrances. Plug in surge protectors, voltage regulators and UPS systems provide point-of-use protection; since the protected equipment plugs directly into the power protection device. The use of remote panel-mount whole circuit protectors does not take the place of point-of-use protection; since it's estimated that more than 60% of surges present in a typical computer circuit are generated from equipment interaction occurring downstream of major power distribution panels.
- Power Factor (True)
- The ratio of active power (Watts) to apparent power (VA). Most computer related equipment has a power factor between .6 and .8. Power factor is the spread between VA and wattage. VA x Power factor = W. See Formulas
- Pseudo Sine Wave
- See PWM Sine Wave
- Pulse Width Modulation
- The process of modulating a pulse train by varying the pulse width proportionately to the modulating signal. Typically refers to a Pulse Width Modulated (PWM) UPS output waveform in battery mode. Usually implies less than a true sine wave output with THD levels around 20%. See PWM Sine Wave
- Pure Sine Wave
- See Sine Wave
- PWM Sine Wave
- Considered a mid-level waveform, a PWM sine wave is suitable for all but the most sensitive of critical computing applications. Rather than the smooth arc typically associated with a sine waveform, a PWM sine wave offers several rectangular steps to help mimic the energy supply of a sine wave. During the 1990's most manufacturers of standby and Line Interactive UPS systems began providing products with PWM sine wave output. See PWM Sine Wave and Sine Wave
- Duplicating devices to the extent that if one were to fail there would be an identical unit to replace the failed unit. Often employed in mission critical networking systems as "mirrored" or "redundant" servers where both machines are performing identical tasks. If one of these servers fails, the application will keep functioning.
- Response Time
- The time it takes for a suppressor to sense a surge or spike and react to it.
- Acronym for Radio Frequency Interference. See Electrical Interference
- Acronym for Root-Mean-Square, a mathematical formula used to calculate the effective values of time-variant waveforms. 120V nominal voltage levels are RMS levels. See Peak Voltages
- Rolling Brownouts
- Rolling Brownouts – A condition where power utilities are forced to purposely create undervoltages and blackouts over their service area to free up capacity so the entire system is not at risk for power failure. When power usage for a given area or community inch up above 95% of capacity, utilities may begin purposely creating brownouts. If the condition worsens and further brownouts will not free up enough energy, the next step is to create blackouts. See Blackout, Undervoltage
- See Undervoltage
- Sine Wave
- Describes an ideal waveform with a smooth arcing alternating waveform. All products using AC power are designed for use with sine wave output. Many high-end Line Interactive and on-line UPS products provide sine wave output at all times. See Square Wave and PWM Sine Wave
- Single Phase Power
- Single phase power protection products protect or pass power with a single AC waveform present. Long-range utility transmission power lines carry 3-phase power. See Three-Phase Power (3-Phase)
- Acronym for Simple Network Management Protocol. A widely used network monitoring and control protocol. Data is passed from SNMP agents, which are hardware and/or software processes reporting activity in each network device (hub, router, bridge, etc.) to the workstation console used to oversee the network. The agents return information contained in a MIB (Management Information Base), which is a data structure that defines what is obtainable from the device and what can be controlled (turned off, on, etc.). Originating in the UNIX community, SNMP has become widely used on all major platforms.
- Also called an impulse, a spike, a spike is a disturbance of the voltage waveform that lasts 1 millisecond. Voltages can rise to hundreds or even thousands of volts in a very short period of time.
- Acronym for Standby Power Supply. See Standby UPS
- Square Wave
- Describes an alternate AC waveform that is considered by many to be the least desirable for critical computing applications. Rather than the smooth arc typically associated with a sine waveform, a square waveform is entirely rectangular and may complicate the operation of sensitive electronics that are used continuously or for long duration. Before 1990, many standby UPS systems provided square wave output in battery mode. Some low cost power inverters still offer square wave output. See PWM Sine Wave and Sine Wave
- Standby UPS
- A UPS that passes line power straight through to the output when conditions are stable, but switches to battery power when line voltage drops near 100-105 volts. Standby UPS systems are typically used to protect home computers and computer workstations. Less frequently known as SPS (standby power supply) or off-line UPS. See Line Interactive UPS & on-line UPS
- A short term voltage increase that exceeds established upper limits for several cycles or more. Often confused with spikes which last less than 1/2 cycle.
- See Overvoltage
- Tap Switching
- A procedure where the coil within an autotransformer is changed to maintain the output voltage at a level "independent" from the source level. Line conditioners and Line Interactive UPS systems use tap switching voltage regulation to maintain acceptable output voltage levels to connected equipment during brownouts and overvoltages.
- A terminal emulation protocol commonly used on the Internet, and TCP/IP-based networks. It allows a user at a terminal or computer to log onto a remote device and run a program. Telnet was originally developed for ARPAnet and is an inherent part of the TCP/IP communications protocol. Although most computers that allow Telnet access require users to have an established account and password, there are some that allow the public to run programs such as search utilities.
- Three-Phase Power (3-Phase)
- Electrical power supplied on three separate outputs with a phase difference of 120 degrees between any two of the outputs. 3-Phase is usually what's delivered to the service entrance of a building from the electrical utility. At the panel, the 3-phases are split into three single-phase legs. Large panel-mount and multi-kVA UPS systems often function with 3-phase.
- Total Harmonic Distortion (THD)
- The ratio of the RMS (root-mean-square) of the harmonic content to the RMS value of the fundamental quantity, expressed as a percent of the fundamental. Typically a supply sine wave is considered acceptable when THD levels are 5% or less. See Harmonics, Harmonic Distortion and Distortion
- Transfer Time
- The time it takes to switch from AC line power to battery power.
- A device used for changing the voltage of an AC circuit and/or isolation in a circuit from its power source.
- Acronym for Transient Voltage surge protector. Another term for surge protector taken from the UL designation for this type of product. See Surge
- When used to describe a specific type of long duration variation, undervoltage undervoltage refers to a measured voltage having a value at least 10% below the nominal voltage for a period of time greater than one minute. Undervoltages frequently occur during air conditioning season due to peak power demands and may last minutes, hours, days or months. See Rolling Blackout
- An acronym for Uninterruptible Power Supply. Any device that provides continuous, acceptable power to its dependent loads no matter what is (or is not) coming in on the commercial utility's power lines (within limits). UPS systems provide battery backup power when utility power fails. See Standby UPS, Line Interactive UPS & Online double Conversion UPS
- User-Replaceable Battery
- Refers to the feature that allows the battery of a UPS to be changed easily, without disassembling the unit.
- Abbreviation for Volt Amps. The unit of measurement of apparent power. Most UPS systems are rated in volt amps. Actual wattage is typically 60-70% of this figure. See formulas, watts, amps, and power factor.
- Volt (V)
- A unit of measure for voltage. Voltage is electrical pressure that forces current to flow in a conductor, such as a wire.
- Voltage Regulator
- A circuit that has a constant output voltage when the input voltage fluctuates.
- Volt-Amp (VA)
- The unit of measurement of apparent power.