Preparation; Dc Voltage Checks - Fluke 8508A User Manual

DC current, Ohms and Temperature function verifications.) It is recommended that the
8-digit resolution mode be used if performance verification shows a borderline out-of­
tolerance condition. In such cases 8-digit mode can be selected and the specifically
borderline verification tests can be repeated. This will provide additional confidence in
the in-tolerance or out-of-tolerance decision made during verification.
* Fluke guarantees 8508A performance verification using specifications stated to 99 %
confidence level.

Preparation

1. Allow the instrument to warm-up under power in the specified environment for at
least 4 hours.
2. Press the
CLEAR
and display the
3. Press the
Test
contact your local authorized Service Center, ensuring that the full circumstances of
the failure are reported.

DC Voltage Checks

The Calibrator can deliver a lethal electric shock.
To avoid electric shock when performing the following adjustment
procedures:
•
Never touch any lead or terminal unless you are absolutely certain
that no dangerous voltage is present.
•
Make sure that signal leads are in a safe condition before you
handle them in any way.
Equipment Configuration
1. On the 8508A press the
configured for internal guard (External Guard is deselected) by checking that the
legend does not appear on the left hand display.
ExGd
2. Ensure that the Calibrator output is set to
Guard (
EX GRD
3. Connect the equipment as described for Routine Adjustment.
• After making the connections allow at least 30 minutes for thermal
emfs in the leads to stabilise.
• To overcome thermal EMF differences when the calibrator polarity is
changed, it is necessary to reference negative Range Gain to the
minimum negative output (-1 digit) on that range.
• For the 8508A 200V and 1kV DC ranges, setting the Calibrator to the
Range Gain point will cause the Calibrator output to revert to Standby.
It will be necessary to reselect OPR to operate the output For the 1kV
DC range the Calibrator cannot be Range locked for the zero
adjustments, omit steps 2, 7 and 8.
key, select
Pwr Up Dflt
menu.
DCV
key and select to initiate a selftest. Should the instrument fail,
START
 Warning
key, and select 1 kV range. Ensure that the 8508A is
DCV
is deselected)
Note
Adjustment and Verification
to restore the power up default configuration
and configured for Internal
STANDBY
Performance Verification
6
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