Safety Information
4
Screen display
The screen of this instrument displays characters in the following manner.
Measurement categories
To ensure safe operation of measurement instruments, IEC 61010 establishes
safety standards for various electrical environments, categorized as CAT II to
CAT IV, and called measurement categories.
Using a measurement instrument in an environment designated with a higher-
numbered category than that for which the instrument is rated could result in a
severe accident, and must be carefully avoided.
Use of a measurement instrument that is not CAT-rated in CAT II to CAT IV
measurement applications could result in a severe accident, and must be care-
fully avoided.
Accuracy
Hioki expresses accuracy as error limit values specified in terms of
percentages relative to reading and full scale, and digits.
CAT II
Primary electrical circuits in equipment connected to an AC electrical outlet
by a power cord (portable tools, household appliances, etc.)
CAT II covers directly measuring electrical outlet receptacles.
CAT III
Primary electrical circuits of heavy equipment (fixed installations) connect-
ed directly to the distribution panel, and feeders from the distribution panel
to outlets.
CAT IV
The circuit from the service drop to the service entrance, and to the power
meter and primary overcurrent protection device (distribution panel).
Full scale
(Maximum displayable value)
Refers to the maximum displayable value of each measurement range.
The instrument has measurement ranges whose values are equal to the max-
imum displayable values. The limit values of full-scale errors are expressed in
percent of full scale (% of full scale, % f.s.).
Reading
(Displayed value)
Refers to the displayed value of the measuring instrument.
The limit values of reading errors are expressed in percent of reading (% of
reading, % rdg).
Digits
(Resolution)
Refers to the smallest change in the indication on the digital measuring instru-
ment, i.e., the numeral one in the rightmost place. The limit values of digit
errors are expressed in terms of digits (dgt).
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