Making Measurements
Using the Measurement Functions
3
Note
Lead Impedance - When making AC current measurements pay particular
attention to the lead impedance, especially lead capacitance at high
frequencies on the lower current ranges. (See "Measuring AC Voltage"
earlier in this chapter.)
Note
Maximum Input Current capability and protection - The front input
terminals may be used to measure currents up to 20 A. The front input A
terminal protection is automatic and self-resetting, and does not interrupt
current flow. Damage is likely to occur if more than 20 A is applied.
The Rear input terminals may be used to measure currents up to 2 A only.
The rear input A terminal is protected by a fuse mounted on the rear panel.
Temperature
The 8508A provides a temperature readout by measuring the resistance of the connected
PRT or SPRT probe, and converting the resitance value to temperature. The multimeter
autoranges between the 200 Ω LoIΩ range and the 2 kΩ Normal Ω range depending on
the resistance value obtained at the temperature being measured.
Press the PRT key to show the PROBE # menu:
adj105f.eps
Select OK to ensure the probe indicated is selected.
Probe# Menu
PRT This function converts resistance measurements from a connected PRT to
temperature. This requires that the characteristics of the probe being used
are available for the conversion algorithm. The 8508A will store up to 100
sets of probe characteristics and the first menu encountered is used to select
from a scrollable list of entered probe identities.
Once selected, the stored probe characteristics are used to configure the
instrument hardware and implement the conversion of subsequent
measurements.
If no probes have been stored, then only a default 100 Ω probe is available.
To add a new probe, select OK. Press the CONFIG key, select PROBE,
then select NEW and follow the instructions for new probe entry below.
Temperature is displayed on the main left-hand display, and the measured
resistance value is also displayed on the right hand display.
PRT Configuration (Temperature Units, Resolution, Probe Configuration Management)
Press the
Config key to see the PRT CONFIG menu:
adj106f.eps
PRT CONFIG Menu
Provides selection for temperature units.
3-25
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