UPS Glossary - Series A - AC, Ambient Temperature, Amprere-hour, Apparent Power, Auxilliary Contact, Average Value, ...

AC
Abbreviation for alternating current.

AC Blackout
Total loss of distributed commercial ac feed power.

AC Brownout
The condition that exists when the AC line voltage drops below some specified value.

AC Input
Electrical power in the form of alternating current (AC) supplied to the UPS and bypass.

AC Input Impedance
The impedance of the AC input at the input terminals of the UPS with the UPS disconnected.

AC Line
The set of conductors that route AC voltage from one point to another.

AC Line Filter
A circuit filter placed in the AC line to condition or smooth out variations that are higher in frequency than the line frequency.

Actuator Fuse
A fuse incorporating some mechanical means to close a dry (un- powered) contact when the fuse opens, such that an alarm and/or control function may take place.

AH
Abbreviation for ampere hour.

Air Gap
A space in the magnetic core, void of magnetic material, used to lower the permeability and increase the ampere turns before the core saturates (provides the required reluctance to the flux path). The gap is filled with a non-magnetic material other than air.

Alarm
A method or signal of attracting attention to an abnormal condition in the UPS.

Alarm Circuit
A circuit with a primary function of alerting an operator by either a visual and/ or audible signal that an abnormal condition exists.

Alarm Interrupt
Stop of normal UPS operation via activation of an alarm condition having a control function.

Alive (Live)
Electrically connected to a source of voltage or electrically charged so as to have a voltage different from that of earth; the term may be used in place of "current-carrying" where the intent is clear, to avoid repetition of the longer term.

Alternate Source
Secondary or backup AC feed to the static switch of the UPS system which is also termed Bypass Source. Often it is unprotected commercial power. See Commercial AC Power.

Alternating Current (AC)
A periodic current the average value of which over a period is zero. Unless distinctly specified otherwise, the term refers to a current that reverses at regularly recurring intervals of time and which has alternately positive and negative values.

Ambient Temperature
The temperature of the environment immediately surrounding the UPS into which the heat of the UPS is dissipated. For forced air-cooled units, the ambient temperature is measured at the air intake. Also see Operating Temperature, Storage Temperature, Temperature and Coefficient.

American Wire Gauge (AWG)
A standard for sizing cross-sectional areas of wire, and for measuring sheet-metal thicknesses.

Ampacity
Current carrying capacity of electric conductors or devices expressed in amperes.

Ampere (A)
Electron or current flow representing the flow of one coulomb per second past a given point in a circuit.

Ampere-Hour (AH)
A measurement of a quantity of electricity computed as the product of current (in amperes) and time (in hours).

Ampere Hour Capacity
The number of ampere-hours which a storage battery can deliver under specified conditions such as temperature, rate of discharge and final voltage.

Ampere Turns
The S1 unit of electromagnetic force defined as the field produced by the flow of one ampere in a single turn of wire in a coil.

Amplifier
A circuit or element that provides gain

Anode
The electrode at which an oxidation reaction occurs. During discharge, the negative electrode of the cell is the anode. During charge, the situation reverses and the positive electrode of the cell is the anode.

Anode Terminal
In semiconductor diodes, the terminal that is positive with respect to the other terminal when the diode is biased in the forward direction. The positive terminal, such as the plate in an electron tube.

Apparent Power
The product of the RMS current times the R/ms voltage.

Arcing Time
In fuses, the time measured from when fuse element melt time ends to when current is interrupted and becomes zero.

Asymmetrical Waveform
1) A current or voltage waveform that has unequal excursions above and below the horizontal axis or whose axis of symmetry is offset from the zero axis (DC offset).
2) A current or voltage waveform that's negative going half cycle differs in time from its positive going half cycle.

Asynchronous
A condition where circuit operating frequency is determined independent of a reference source.

Attenuation
Decrease in amplitude or intensity of a signal.

Audible Noise
Frequencies that can be detected by the human ear produced by the battery charger and/or inverter and measured in decibels (a measure of intensity). The acoustical noise.

Auto-retransfer
A transfer from the "alternate source" position of a static switch to the "inverter" position without operator intervention.

Auto-retransfer Circuit
Electronic circuit which simulates the operation of "Inverter to load" pushbutton.

Auto-transfer
A Transfer from the "Inverter." position of a static switch to the alternate source position without operator intervention.

Auto-Transformer
A transformer whose primary and secondary are electrically connected.

Automatic Transfer
A transfer is made by the UPS without operator/user involvement and is usually based upon the status or condition of the input/output AC power.

Auxiliary Contacts
An accessory attached to a circuit breaker or magnetic switch having low ampacity contacts that operate coincident with the on-off-trip operation of the main device and to provide secondary circuit functions, as lights, control signals, or interlocking functions.

Average Value
1) The value of the function or quantity averaged over a full cycle unless otherwise specified. The value of alternating current or voltage of sine wave form that is found by dividing area under one alternation by distance along X axis between 0 and 180'.

Eavg = 0.637 Epeak

E avg= 2/T e(t)dt