Safety Information
6
Accuracy
We define measurement tolerances in terms of f.s. (full scale), rdg. (reading) and
dgt. (digit) values, with the following meanings:
Measurement categories
This device complies with CAT III (600 V)/ IV (300 V) safety requirements.
To ensure safe operation of measurement roducts, IEC 61010 establishes safety
standards for various electrical environments, categorized as CAT II to CAT IV, and
called measurement categories.
Using a measurement device in an environment designated with a higher-numbered
category than that for which the device 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 mea-
surement applications could result in a severe accident, and must be carefully
avoided.
f.s.
(maximum display value or scale length)
The maximum displayable value or scal
e length. 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
instrument.
dgt.
(resolution)
The smallest displayable unit on a digi
tal measuring instrument, i.e.,
the input value that causes the digital display to show a "1" as the
least-significant digit.
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)
connected directly to the distribution panel, and feeders from the dis-
tribution 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).
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