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Rockwell Automation Publication 1426-UM001G-EN-P - November 2014 449

Glossary

The following terms and abbreviations are used throughout this manual. For

definitions of terms not listed here, refer to the Allen-Bradley Industrial

Automation Glossary, publication AG-7.1

Aggregation In power quality measurement, the process of computing a single value from

multiple measurements over a defined time interval. The value is computed by

taking the square root of the arithmetic mean of the squared input values over a

defined time interval (that is,180 cycles, 10 minutes, etc). See EN 61000-4-30

standard for more information.

Amperes (A) The units of electrical current or rate of flow of electrons. One volt across one

ohm of resistance causes a current flow of one ampere. A flow of one coulomb per

second equals one amp.

Apparent Power The product of voltage magnitude and current magnitude in a circuit. Units are

VA or some multiple thereof.

Balanced Load An alternating, current power system consisting of more than two current

carrying conductors in which these current carrying conductors all carry the same

current.

Billing Demand The demand level that a utility uses to calculate the demand charges on the

current month's bill. Various methods can be used to determine the value, such as

minimum demand, peak demand or a ratchet clause. It can be based on Watt

Demand, VA Demand, VAR Demand or some combination of these. A rate at

which a transmission occurs, where one baud equals one bit per second.

Burden The electrical load placed on source of VA or the load an instrument or meter

places on a current or potential transformer. All current and potential

transformers have a rated burden that cannot be exceeded or else transformer

transformation accuracy deteriorates.

Capacitor A device consisting essentially of two conducting surfaces separated by an

insulating material or dielectric. A capacitor stores electrical energy, blocks the

flow of direct current, and permits the flow of alternating current to a degree

dependent upon the capacitance and frequency. Capacitors can also be used to

adjust the power factor in a system.

Connected Load The total load that a customer can impose on the electrical system if everything

was connected at one time. Connected loads can be measured in horsepower,

watts or volt-amperes. Some rate schedules establish a minimum demand charge

by imposing a fee per unit of connected load.

Crest Factor A measure of the amount of distortion present in a waveform. It can also be used

to express the dynamic range of a measurement device. Crest Factor is the ratio of

the peak to the RMS. For a pure sinusoidal waveform, Crest Factor equals the

square root of 2 (1.414).

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MSI 5000V Master-S Manuale Utente Pagina 449