Fluke 8846A - How the Meter Processes Output; Triggering Input

8845A/8846A
Calibration Manual
1-22
Interpreting Accuracy Specifications
The following sections provide a clearer understanding of specifications over time and
with temperature variations.
24
-Hour Accuracy
The 24
-hour accuracy specification indicates the Meter's relative accuracy over its full
measurement range for short time intervals and within a stable environment. Short
-term
accuracy is usually specified for a 24
-hour period and for a ±1 °C temperature range.
90
-Day and 1-Year Accuracy
The longer
duration accuracy specifications are valid at the calibration temperature (Tcal)
±5 °C temperature range. These specifications include the initial calibration errors plus
the Meter's long
-term drift errors.
Temperature Coefficients
Accuracy is usually specified at the calibration temperature (T
cal) ±5 °C temperature
range. This is a common temperature range for many operating environments. Add
additional temperature coefficient errors to the accuracy specification if the Meter is
operated outside the ±5 °C temperature range (the specification is per °C).
Configuring for Highest Accuracy Measurements
The measurement configurations shown below assume that the Meter is in its power–on
or reset state. It is also assumed that auto-ranging is enabled to ensure proper full-scale
range selection.
DC Voltage, DC Current, and Resistance Measurements
Select NPLC and 100 (NPLCs) for highest instrument resolution and accuracy.
For the best dc voltage accuracy, set INPUT HIGH INPUT Z (impedance) to GOhm (for
the 100 mV, 1 V, and 10 V ranges).
For the best resistance measurement accuracy, use the 4
-wire ohms function (4W).
For 2
-wire ohms, dc voltage and dc current measurements, set AUTOZERO to ON to
remove thermal EMF and offset errors.
Zero the test lead resistance for 2
-wire and 4-wire ohms measurements and zero to
remove any interconnection offset for dc voltage measurements.
AC Voltage and AC Current Measurements:
Set the AC FILTER to 3 Hz: SLOW.
Frequency and Period Measurements:
Set the GATE TIME to 1 sec.