Temperature Measurements; Other Sources Of Measurement Error; Loading Errors (Ac Volts) - Keysight Technologies EDU34450A User Manual

Capacitance is calculated by measuring the change in voltage (ΔV) that occurs over a "short aperture" time, (Δt). The
measurement cycle consists of two parts: a charge phase and a discharge phase.
The change in voltage (ΔV) and "short aperture" time (Δt), vary by range, in order to minimize noise and increase
reading accuracy. The following table lists the current source and reading rate at full scale during the measurement.
Range
1 nF
10 nF
100 nF
1 μF
10 μF
100 μF
1 mF
10 mF
The values of capacitance and loss resistance measured with the instrument may differ from the values measured
using an LCR meter. This is to be expected, since this is essentially a DC measurement method, while LCR
measurement uses applied frequencies anywhere from 100 Hz to 100 kHz. In most cases, neither method measures
the capacitor at its exact frequency of application.
For the best accuracy, take a zero null measurement with open probes, to null out the test lead capacitance, before
connecting the probes across the capacitor to be measured.

Temperature Measurements

The instrument measures temperature by measuring the temperature sensitive resistance of 5 kΩ thermistors.
Thermistors consist of semiconductor materials and provide roughly 10 times the sensitivity of an RTD. Because
they are semiconductors, their temperature range is more limited, commonly to –80 °C to 150 °C. Thermistors have
highly non-linear, temperature-resistance relationships; therefore their conversion algorithms are more complex.
Keysight instruments use the standard Hart-Steinhart Approximation to provide accurate conversions.

Other Sources of Measurement Error

Loading Errors (AC Volts)

In the AC voltage function, the input of the instrument appears as a (at least) 1.1 MΩ resistance in parallel with <100
pF of capacitance. The cabling that you use to connect signals to the instrument also adds capacitance and loading.
For low frequencies, the loading error is:
Keysight EDU34450A User's Guide
Current Source
100 nA
100 nA
1 μA
1 μA
10 μA
100 μA
500 μA
1 mA
Reading Rate at Full Scale
1.0/second
0.5/second
1.5/second
0.25/second
0.25/second
0.25/second
0.25/second
0.15/second
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