Ieee std 1159-1995, ieee recommended Practice for Monitoring Electric Power Quality

 
3.1.1 accuracy: 
The freedom from error of a measurement. Generally expressed (perhaps erroneously) as
 
percent inaccuracy.
Instrument accuracy is expressed in terms of its uncertaintyÑthe degree of deviation
from a known value. An instrument with an uncertainty of 0.1% is 99.9% accurate. At higher accuracy lev-
els, uncertainty is typically expressed in parts per million (ppm) rather than as a percentage.
1
IEC publications are available from IEC Sales Department, Case Postale 131, 3, rue de VarembŽ, CH-1211, Gen•ve 20, Switzerland/
Suisse. IEC publications are also available in the United States from the Sales Department, American National Standards Institute, 11
West 42nd Street, 13th Floor, New York, NY 10036, USA.
2
IEEE publications are available from the Institute of Electrical and Electronics Engineers, 445 Hoes Lane, P.O. Box 1331, Piscataway,
NJ 08855-1331, USA.
3
Information on references can be found in clause 2.
4
The numbers in brackets correspond to those bibliographical items listed in annex B.

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IEEE
MONITORING ELECTRIC POWER QUALITY
Std 1159-1995
3
 
3.1.2 accuracy ratio: 
The ratio of an instrumentÕs tolerable error to the uncertainty of the standard used to
calibrate it.
 
3.1.3 calibration:
Any process used to verify the integrity of a measurement. The process involves compar-
ing a measuring instrument to a well defined standard of greater accuracy (a calibrator) to detect any varia-
tions from specified performance parameters, and making any needed compensations. The results are then
recorded and filed to establish the integrity of the calibrated instrument.
 
3.1.4 common mode voltage:
A voltage that appears between current-carrying conductors and ground.
b
The noise voltage that appears equally and in phase from each current-carrying conductor to ground.
c