Hioki RM3545, Instruction Manual, Page: 288 / 364

Chapter 13 Specifications
280
We define measurement tolerances in terms of f.s. (full scale), rdg. (reading) and dgt. (digit) values,
with the following meanings.
Example accuracy calculations
(Digits in excess of display range are truncated.)
• Resistance measurement accuracy when using the Z3003
RM3545 measurement conditions: 100 k
Ω
range, measurement current of 100
μ
A,
OVC off, 0ADJ on, FAST, measurement target of 30 k
Ω
Resistance measurement accuracy ±(0.008%rdg.+0.005%f.s.)
The accuracy error component is calculated first, and then the total error component is
calculated.
(1) Calculating the accuracy error component
•
Effects of leak current
The effects of leak current are determined based on the ratio of leak current to mea-
surement current. The result is added to the reading error (rdg.).
Additional error = (1×10
-9
) / (100×10
-6
)×100 = 0.001%rdg.
•
Effect of measurement speed (During FAST measurement, the integration time is not a
whole-number multiple of the power supply cycle.)
If the integration time is not a whole-number multiple of the power supply cycle, the
effects of commercial power noise will be more pronounced.
Additional error = 0.005×0.5 = 0.0025 [%f.s.]
•
Effect of offset voltage
The relay and connector thermoelectric force is observed as a measured value offset.
When using with OVC on, there is no need to add this.
Additional error = (10×10
-6
) / (100×10
-6
) = 0.1
Ω
•
Effect of offset resistance fluctuations
During 2-wire operation, results are affected by fluctuations in the internal offset resis-
tance.
Additional error +0.1
Ω
(2) Calculating the total error component
4-wire: ±((0.008+0.001)%×30 k
Ω
+(0.005+0.0025)%×100 k
Ω
+0.1
Ω
) = ±10.3
Ω
2-wire: ±((0.008+0.001)%×30 k
Ω
+(0.005+0.0025)%×100 k
Ω
+0.1
Ω
+0.1
Ω
) = ±10.4
Ω
About Instrument Accuracy
f.s.
(maximum display value)
This is usually the name of the maximum displayable value. For this instrument, it
indicates 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 digital measuring instrument, i.e., the input value
that causes the digital display to show a “1” as the least-significant digit.