Fluke 5520A Operator's Manual page 394

5520A
Operators Manual
true power
The actual power (real power) used to produce heat or work. Compare to 'apparent
power."
true value
Also called legal value, the accepted, consensus, i.e., the correct value of the quantity
being measured.
uncertainty
The maximum difference between the accepted, consensus, or true value and the
measured value of a quantity. Uncertainty is normally expressed in units of ppm (parts
per million) or as a percentage.
units
Symbols or names that define the measured quantities. Examples of units are: V, mV, A,
kW, and dBm. See also "SI System of Units."
UUT (Unit Under Test)
An abbreviated name for an instrument that is being tested or calibrated.
var
Symbol for voltampere reactive, the unit of reactive power, as opposed to real power in
watts.
verification
Checking the functional performance and uncertainty of an instrument or standard
without making adjustments to it or changing its calibration constants.
volt
The unit of emf (electromotive force) or electrical potential in the SI system of units.
One volt is the difference of electrical potential between two points on a conductor
carrying one ampere of current, when the power being dissipated between these two
points is equal to one watt.
voltage guard
A floating shield around voltage measurement circuitry inside an instrument. The
voltage guard provides a low-impedance path to ground for common-mode noise and
ground currents, thereby eliminating errors introduced by such interference.
watt
The unit of power in the SI system of units. One watt is the power required to do work at
the rate of one joule/second. In terms of volts and ohms, one watt is the power dissipated
by one ampere flowing through a one-ohm load.
working standard
A standard that is used in routine calibration and comparison procedures in the
laboratory, and is maintained be comparison to reference standards.
zero error
Same as offset error. The reading shown on a meter when an input value of zero is
applied is its zero or offset error.
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