Agilent Technologies 4349B, Руководство пользователя

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4349B
Note on Measuring Insulation Resistance of Capacitors
This section provides information on how to measure the insulation resistance of capacitors
using the 4349B and an external DC voltage source . It covers the following subjects:
The external DC voltage source .
How to select the optimum measurement range .
A dditional errors caused by the external DC voltage source .
How to reduce the measurement error .
The External DC V oltage Source
When measuring a capacitor's leakage current (insulation resistance), the DC voltage source's
noise passes through the capacitor and ows into the ammeter . If the noise level is too high,
the current measurement accuracy is degraded. T o avoid this problem, use a low noise external
voltage source .
How to Select the Optimum Measurement Range
The useable measurement range is restricted by the DUT's capacitance value . It is important
to consider not only the DC current measurement value but also the DUT's capacitance value
when selecting the measurement range . Select the optimum measurement range as follows:
1. Calculate the DC current measurement value (I
m
) from the DUT's (capacitor) resistance
(R
dut
) and the test voltage (V
s
) as I
m
=V
s
/R
dut
.
2. Select the lowest range that can measure the current value calculated in step 1 using
T able 6-1 .
3. If the DUT's capacitance value is within the Measurable Capacitance of the range selected in
step 2, you can use that range for measuring the DUT .
If the DUT's capacitance value is higher than the Measurable Capacitance of the
range selected in step 2, change the measurement range to a higher range (or select a
slower measurement speed) until the DUT's capacitance value is within the Measurable
Capacitance .
6-8 Application Measurement