3 Adjustment Procedures
44 Keysight 3458A Calibration Manual
Equipment required: A 10 kW resistance standard (the resultant accuracy of the
multimeter depends on the accuracy of the resistance standard used).
1 Select the 4-wire ohms measurement function (use the shifted OHM key).
2 Execute the OCOMP ON command (use the front panel Offset Comp W key).
When offset compensated ohms is enabled (OCOMP ON command), the default
delay time used by the multimeter for this adjustment is 50 ms (50 ms is the
settling time used after the current source is switched on or off). For most
resistance standards and cabling, this provides adequate settling time for the
measurements made during the adjustment. If, however, the resistance
standard and/or cabling has slow transient response or high dielectric
absorption you should specify a longer delay. You can determine this
experimentally prior to performing the following adjustment by measuring the
resistance standard using a 50 ms delay and then measuring it using a much
longer delay (e.g., 1 second). If the two measurements are significantly different,
you should use a longer delay in the adjustment procedure. You must specify the
longer delay using the DELAY command prior to executing the CAL command
(step 5). For example, to specify a 200 ms delay execute: DELAY 200E-3. The
multimeter will then use the specified delay in the adjustment. If a value of less
than 50 ms is specified, the multimeter will automatically use a delay of 50 ms.
Do not specify a delay longer than 60 seconds; a delay >60 seconds will
adversely affect the adjustment.
Resistance standards from 1 kW to 12 kW can be used for the procedure.
However, using a resistance standard <10 kW will degrade the multimeter's
accuracy specifications.
You can perform this adjustment with offset compensation disabled (OCOMP
OFF command). This eliminates the settling time requirement (DELAY command)
when dealing with high dielectric absorption in the adjustment setup (see note
as the beginning of this adjustment). However, with offset compensation
disabled, any offset voltages present will affect the adjustment. For most
applications, we recommend enabling offset compensation for this adjustment.
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