Front Panel Operation
2-60
• Resistivity Tests:
Normal (Surface and volume)
Alternating Polarity
• Surface Insulation Resistance (SIR) Test
• Sweep Tests:
Square-wave
Staircase
2.14.1 Test descriptions
The following information describes each test, shows the
connections to the Model 6517A, and explains how to set up
the Model 6517A for the measurements.
The results of a test are stored in the buffer. If, for example,
a test performs 10 measurements, those 10 readings will be
stored in the buffer at locations 0 through 9. If a test only per-
forms one measurement, then that single reading will be
stored at memory location 0. Note that when a test is per-
formed, previous data stored in the buffer will be lost.
Diode leakage current test
This test is used to measure the leakage current for a diode.
Figure 2-47 shows the connections and the simplified sche-
matic. By sourcing a positive voltage, the leakage current
through the diode will be measured. Note that if you source
a negative voltage, you will forward bias the diode. Resistor
R is used to limit current in the event that the diode shorts out
or it becomes forward biased. Select a value of R that will
limit current to 20mA or less.
This test allows you to measure the current at various voltage
levels. When the test is configured, you specify the start volt-
age (START V), the step voltage (STEP V), the stop voltage
(STOP V) and the DELAY between steps. Figure 2-48 shows
an example using the default test parameters. When the test is
run, 10 current measurements will be performed (one at each
voltage step) and stored in the buffer. This test is selected and
configured from the CONFIGURE SEQUENCE menu
(DEV-CHAR; DIODE). See paragraph 2.14.2 for details.
Capacitor leakage current test
This test is used to measure the leakage current for a capaci-
tor. The magnitude of the leakage is dependent on the type of
dielectric and the applied voltage. Figure 2-49 shows the
connections for this test. A resistor and a diode are used to
limit noise for the measurement.
For this test, a fixed voltage (BIAS V) is applied to the capac-
itor for specified time intervals to allow the capacitor to
charge (current decays exponentially with time). The leakage
current is measured at each interval and stored in the buffer.
This test is selected and configured from the CONFigure SE-
QUENCE menu (DEV-CHAR; CAPACITOR). See para-
graph 2.14.2 for details.
2.13.3 Zero correct
The Z-CHK and REL keys work together to cancel (zero cor-
rect) any internal offsets that might upset accuracy for volts
and amps measurements.
Perform the following steps to zero correct the volts or amps
function:
1. Select the V or I function.
2. Press Z-CHK to enable Zero Check.
3. Select the range that will be used for the measurement.
4. Press REL to zero correct the instrument (REL indicator
will be lit and "Zcor" displayed).
NOTE
For the volts function, the "Zcor" message
will not be displayed if guard was already
enabled ("Grd" displayed).
5. Press Z-CHK to disable zero check.
6. Readings can now be taken in the normal manner.
Note that the instrument will remain zeroed even if the in-
strument is upranged. If downranged, re-zero the instrument.
To disable zero correct, press REL with zero check enabled.
2.13.4 "Properly zeroed"
(as defined for instrument
specifications)
For taking measurements "when properly zeroed", per
instrument specifications:
1. Perform the zero correct procedure described in
section 2.13.3.
2. Provide a zero input from a calibration source, or short
leads in V function, open leads in I function.
3. Press REL to null remaining measurement offsets.
4. Readings can now be taken in the normal manner. (REL
indicator will remain on.)
NOTE
Repeat steps 1 through 4 whenever the
measurement range is changed.
To disable REL mode, press REL with zero check not
enabled.
2.14 Test sequences
The Model 6517A has the following built-in test sequences:
• Device Characterization Tests:
Diode Leakage Current
Capacitor Leakage
Cable Insulation Resistance
Resistor Voltage Coefficient
Содержание 6517A
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