Temperature Measurements; Probe Type Choice; 2-Wire Vs. 4-Wire Measurements - Agilent Technologies 34410A User Manual

4 Measurement Tutorial

Temperature Measurements

The multimeter allows the measurement of temperature by measurement
of the temperature sensitive resistance of two different "Probe" types: the
resistance temperature detector (RTD) of .0385%/
2.2 KW, 5 KW or 10 KW). There are a number of measurement parameter
and technique choices available to you, and these will affect various
aspects of the measurement:
• Temperature range and resolution can direct the probe–type choice.
• Choice of four–wire or two–wire technique will affect measurement
• Use of the auto zero feature will impact measurement speed and
• Choice of integration (measurement time) setting will affect measuement
• Use of the offset compensation feature can eliminate residual voltages

Probe Type Choice

RTD's provide very accurate, highly linear relationships between resistance
and temperature, over a range of roughly –200 to 500
little conversion complexity for an RTD since it is so intrinsically linear.
The multimeter provides measurement for the IEC751 standard RTD,
which has a sensitivity of .0385%/
Thermistors consist of semiconductor materials, and provide roughly
10 times the sensitivity of the RTD. Because they are semiconductors,
their temperature range is more limited, commonly to –80
Thermistors have highly non–linear temperature–resistance relationships;
therefore their conversion algorithms are more complex. The Agilent
multimeters use the standard Hart–Steinhart Approximation to provide
accurate conversions, with a typical resolution of .08
2
As with resistance measurements, four–wire temperature measurement is
more accurate, since it completely eliminates errors due to lead wire
resistance. Alternately, you can use the multimeter's Null function to
remove the test lead resistance from the measurement (see
Reading:"
112
accuracy.
accuracy.
accuracy and power–line noise rejection.
in the test instrumentation or circuit.
Wire vs. 4 Wire Measurements
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