Measurement Accuracy of the electrical measuring instruments

A

Hioki expresses accuracy as error limit values specified in terms of percentages relative to reading, full scale, and digits.

- Full scale (Length of scale / Maximum displayable value)
Refers to the length of the scale or maximum displayable value of each measurement range. The limit values of full-scale errors are expressed in percent of full scale (% of full scale. % f.s.).

- Reading (indicated value / displayed value)
Refers to the indicated/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 instrument, i.e., the numeral one in the rightmost place. The limit values of digit errors are expressed in terms of digits (or "dgt.").

The upper and lower limits of accuracy are obtained by adding the calculated accuracy values.
<Calculation example>
Accuracy specification: ±1.0% rdg. ±3 dgt.
Measurement range: 300.0 V
Measured value: 100.0 V

Since the measured value (displayed value) is 100.0 V,
(1) rdg. error: 1.0% of 100.0 V = ±1.0 V
(2) dgt. error: Since the minimum resolution is 0.1 V, 3 dgt. = ±0.3 V
(3) Total error (1)+(2): ±1.3 V = 1.3%

The lower and upper limits of accuracy are 98.7 to 101.3 V when measuring 100.0 V from total error (3).