Safety Information
3
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
We define measurement tolerances in terms of f.s. (full scale), rdg. (reading) and
dgt. (digit) values, with the following meanings:
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).
f.s.
(maximum display value)
The maximum displayable value. This is usually the name of the currently
selected range.
rdg.
(reading or displayed value)
The value currently being measured and indicated on the measuring instru-
ment.
dgt.
(resolution)
The smallest displayable unit on a digital measuring instrument, i.e., the
input value that causes the digital display to show a "1" as the least-signifi-
cant digit.
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