Fluke Calibration 5730A, Operator'S Manual, Page: 254 / 260

5730A
Operators Manual
C-4
ground
The voltage reference point in a circuit. Earth ground is a connection through a ground
rod or other conductor to the earth, usually accessible through the ground conductor in an
ac power receptacle.
ground loops
Undesirable currents induced when there is more than one chassis ground potential in a
system of instruments. Ground loops can be minimized by connecting all instruments in a
system to ground to one point.
guard
See “voltage guard” and “current guard.”
International System of Units
Same as “SI System of Units”; the accepted system of units. See also “units”, “base
units”, and “derived units.”
legal units
The highest echelon in a system of units, for example the U.S. National Bureau of
Standards volt.
life-cycle cost
The consideration of all elements contributing to the cost of an instrument throughout its
useful life. This includes initial purchase cost, service and maintenance cost, and the cost
of support equipment.
linearity
The relationship between two quantities when a change in the first quantity is directly
proportional to a change in the second quantity.
linearity error
Linearity error occurs when the response curve of a meter is not exactly a straight line.
This type of error is measured by fixing two points on the response curve, drawing a line
through the points, then measuring how far the curve deviates from the straight line at
various points on the response curve.
MAP (Measurement Assurance Program)
A program for a measurement process. A MAP provides information to demonstrate that
the total uncertainty of the measurements (data), including both random error and
systematic components of error relative to national or other designated standards is
quantified, and sufficiently small to meet requirements.
MTBF (Mean Time Between Failures)
The time interval in operating hours that can be expected between failure of equipment.
MTBF can be calculated from direct observation or mathematically derived through
extrapolation.