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Alternating Current (AC)

The direction of an electric charge that is flowing in a circuit is constantly being reversed back and forth.

Amp (ampere)

The standard unit of measure for electrical current, defined as the amount of electrical flow equal to one coulomb per second.

Apparent Power

The product of the applied voltage and current in an AC circuit.

Blackout

A power failure in which line voltage drops to zero.

Brownout

A drop in voltage in electrical power supply.

Buck/Boost

Full automatic voltage regulation in a UPS stabilizes low voltage (boost) and high voltage (buck) to maintain nominal 230V power, without resorting to battery power when minor power fluctuations occur.

Coaxial Cable

Cables that are made of an inner conductor surrounded by an insulator and a shield that are generally used for TV antennas, satellite dishes, cable modems and certain computer networking applications.

Current

The flow of electric charge, measured in amps.

DHCP

Dynamic Host Configuration Protocol (DHCP), automatically assigns an IP address to a device on a network.

Direct Current (DC)

The unidirectional flow of a electric charge.

Double-Conversion UPS

This high-end UPS system converts incoming utility AC power into DC power and then back into AC power, charging connected devices with the UPS battery. The isolated process ensures clean and stable output voltage and zero transfer time. This UPS system is ideal for equipment sensitive to power fluctuations such as corporate data centers, servers, and network and storage devices.

Efficiency (Energy Conversion Efficiency)

The ratio between the amount of apparent power and the amount of true power used by an electrical device. The closer the true power value is to the apparent power, the more efficient the device.

Electromagnetic Interference (EMI)

Commonly referred to as line noise, these interference signals can disrupt or degrade the performance of a circuit by inserting abnormalities into the system. Also referred to as radio frequency interference (RFI) when in high or radio frequency.

Frequency

The number of cycles in a given time period, which is measured in Hertz.

Ground

An electrical system connection that serves as a conduit between the circuit and earth.

Half-Load

The midpoint in the maximum load capacity for a UPS.

Hard-wired

High amperage devices that require installation by a qualified electrician to be directly wired-in, instead of simply being plugged in to an outlet.

Hertz (Hz)

The unit for frequency, defined as the number of cycles per second.

Hot-Swappable Battery

A term used to describe the functions of replacing a UPS battery without shutting down the unit.

Joule

A measure of electrical energy — one joule is defined as the energy needed to pass one ampere of current through one ohm of resistance.

Line-Interactive UPS

Functions the same as a standby UPS, with the additional feature of some voltage regulation built in. It switches to battery power when voltage drops too low, just as a standby UPS does, however if the voltage only drops slightly, a line-interactive UPS corrects this without using battery power. The functionality of these mid- to high-grade units falls between standby and online UPS units.

Load

The amount of power consumed by an electrical device on a circuit. Load capacity is a critical factor in selecting a UPS or surge protector.

MOV

Metal Oxide Varistor is an electronic component that is used to protect circuits against excessive, short-lived, voltages.

Nominal Voltage

The standard voltage for a circuit or system. Common nominal voltages in the U.S. include 120VAC, 208VAC and 240VAC; while nominal voltage in the EU is 230VAC.

Overvoltage

This occurs when incoming voltage is higher than normal but not high enough to be classified as a surge.

Power Factor (PF)

The ratio of real power (watts) to apparent power (VA), expressed as a number between 0 and 1. Watts divided by VA = Power Factor

Power Factor Correction

Controls the incoming power to a power supply in order to bring the power factor as close to unity power as possible.

Radio Frequency Interference (RFI)

See Electromagnetic Interference.

Real Power

The amount of power being drawn by a system, measured in watts. Real power is a function of VA (apparent power) and the power factor.

RJ11, RJ14, RJ45

The abbreviation of registered jack (RJ) – RJ11 is for standard phone lines, RJ14 is for multiple phone lines and RJ45 is for Ethernet.

Runtime

The maximum period of time battery power is output from a UPS to its connected devices during a power interruption. Runtime is dependent upon the total load of all connected equipment.

Simulated Sine Wave

A modified or approximated sine wave AC power output. Simulated (or nonsinusoidal) waveforms may also be referred to as a squared sine wave, modified sine wave, trapezoidal sine wave or quasi sine wave.

Sine Wave

A smooth, repetitive oscillation of AC power.

Single Phase Power

Refers to the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison.

SMTP

Simple Mail Transfer Protocol is the standard for e-mail transmission on the Internet

SNMP

Simple Network Management Protocol is a commonly used protocol for devices to communicate over a network.

Spike

A spike is a sudden, brief power surge, usually lasting less than 1ms.

Standby UPS

A UPS that passes utility power straight through to the output when conditions are stable, but switches to battery power when utility voltage drops below an acceptable level.

Surge

Periods when line voltage increases dramatically, typically lasting longer than 1ms, but less than a few seconds, though they can last longer.

Total Harmonic Distortion (THD)

A calculated measure of the reduction in sine wave clarity caused by stray wave frequencies.

Thermal Dissipation

The process of dissipating heat from an electrical system via air or liquid cooling; also a term for the amount of heat a device can emit.

Transfer Time

The time it takes UPS to switch from AC power to battery power.

Transformer

A device that converts AC line voltage to a higher or lower value.

U

The standard unit of measure for rack-mounted equipment. A device measuring 1U is 1.75 inches high, 2U is 3.50 inches, etc.

Undervoltage

Related to both brownout and voltage sag, undervoltage falls between these two, occurring when voltage is lower than normal for an extended period of time without recovering, but not to low that the electronic device will not function.

USB (HID Compliant)

Universal Serial Bus devices are used to connect various components to a computer. An HID (Human Interface Device) compliant USB follows a specific protocol for communication that allows it to be used with virtually any system.

Volt

The difference in electric potential between two points when one amp of current dissipates one watt of power.

Volt-Ampere

The unit used to express apparent power.

Voltage Regulator

A device or component that normalizes voltage to a certain standard when it is fluctuating.

Watt

A unit of measure for true power consumption.

Waveform

Is a representation (or form) of how alternating current (AC) varies with time. Common waveform representations include sine wave, square wave and trapezoidal wave. An instrument called an oscilloscope can be used to visually represent a wave as a repeating image on a screen.

Wiring-Fault

Refers to an abnormal flow of current that is due to an improperly grounded electrical outlet.