Hioki 3504-40 C HiTester, Instruction Manual

Page: 9 / 292

3
Accuracy
We define measurement tolerances in terms of rdg. (reading) and dgt. (digit) val-
ues, with the following meanings:
Measurement categories
To ensure safe operation of measurement instruments, IEC 61010 estab-
lishes safety standards for various electrical environments, categorized as
CAT II to CAT IV, and called measurement categories.
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) con-
nected directly to the distribution panel, and feeders from the distribu-
tion 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).
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
carefully avoided.
Other Symbols
Indicates a prohibited action.
See Indicates the location of reference information.
Indicates quick references for operation and remedies for
troubleshooting.
*
Indicates that descriptive information is provided below.
rdg.
(reading or displayed value) The value currently being measured and
indicated on the measuring unit.
dgt. (resolution) The smallest displayable unit on a digital
measuring unit/ device/ product, i.e., the
input value that causes the digital display
to show a "1" as the least-significant digit.