Fluke 8840A - Measuring Voltage and Resistance; External Cleaning; Measuring Current

Operating Jnstr
MAKING MEASU piom EMEMS
CIRCUIT
I
SENSE terminals for
4 WIRE &wire resistance
measurement only.
/
Figure 2-10. Measuring Current
While an offset is enabled, the
8840A indicates arn over-
range condition if either of the following conditioqs
occur:
The input signal is overrange
The calculated reading is overrange
For example, suppose the iWrument is in the 20V range
of the VDC function and you store
an offset of +1h. The
maximum positive voltage reading that
can be +played
without overranging is +4.9999V, which is actually a
+19.9999V input signal. The maximum
reading that
can be displayed without
-19.9999V, which is actually
a -4.9999V
can measure a greater range of
higher range.
When in autorange, the 8WA selects the range appro-
priate for the input signal, regardless of any stored offset.
If, for example, a +10V offset is stored, and a +lVinput is
applied, the
8&40A will autorange to the 2V r
display
an overrange condition since it cannot dig; -7;
on the 2V range. Manual rhge control could be used to
lock the
8840A into the 2OV range in this caw.
Applications of the offset feature include correding for
test lead resistance in 2-wire resistance measuAements,
nulling offset currents or voltages, measu~g voltake devi-
ations, and matching resistors.
2-30. EXTERNAL CLEANING
WARNING
TO AVOID ELECTRIC SHOCK OIR
INSTRUMENT AGE, NEVER G@
WATER CASE. TO AVO~D
INSTRUMENT DAMAGE, NNER
APPbY
SOLVENTS TO THiE INSTRUMENT.
-
Should the 8840A case require cleaning, wipe the instru-
Figure
2-9. Measuring Voltage and Resistance
ment with
a cloth that is lightly dampened with wqter or a
mild detergent solution.
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