506 Rockwell Automation Publication 1426-UM001J-EN-P - August 2019
Glossary
Volt a g e Flu c tuat i on A series of rms voltage magnitude changes or a low frequency, less than 40 Hz,
periodic variation of the nominal voltage envelop. The variations can result in
modulation of the luminance of light sources that are connected to the power
system. The modulation or ‘flicker’ can cause discomfort in individuals that are
exposed to the flickering light. See EN 61000-4-15 for more details. See also
Flicker.
Volt a g e Int er r upt i on Voltage sag with a residual voltage less than 10% of nominal.
Vol ta g e O v er D e v i ation The ratio of the measured rms voltage to the nominal voltage expressed as a
percent when the measured voltage is greater that the nominal voltage. See also
Rapid Voltage Changes.
Volt a g e Und e r D e v i ati o n The ratio of the measured rms voltage to the nominal voltage expressed as a
percent when the measured voltage is less than the nominal voltage. See also
Rapid Voltage Changes.
Wat t ( W ) A measure of real power. The unit of electrical power required to do work at the
rate of one joule per second. Watt is the power that is expended when one ampere
of direct current flows through a resistance of one ohm. Equal to apparent power
VA times the power factor.
Watt Demand Power during a predetermined interval. The highest average, for example, Peak
demand is commonly used for billing.
Watt Hour (Whr) The number of watts used in one hour. Because the power usage varies, it is
necessary to integrate this parameter over time. Power flow can be either forward
or reverse.
Wa t t m e t e r An instrument for measuring the real power in an electric circuit. Its scale is
usually graduated in watts, kilowatts, or megawatts.
Wa v e f o r m Numerical representation of the instantaneous value of a measured parameter
(that is, voltage or current) as a function of time. Can be presented graphically or
in a tabular form.
Wiring Correction In reference to the PowerMonitor™ 5000 unit, the correction that is performed by
the device to correct the effect of physical wiring errors without actually accessing
the device or moving any of the connected wires.
Wiring Diagnostics In reference to the PowerMonitor 5000 unit, this check is an analysis that is
performed by the device to verify that the unit is properly connected. In the event
connection errors are present, they are identified for the user. The user then has
the option of physically correcting the errors or of using the ‘virtual’ wiring
correction capability of the device to allow the device to correct the errors
through appropriate internal adjustments. See also Wiring Correction
.
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