5080A
Service Manual
50
AC Current Calibration
Note
DC Current must be calibrated before you continue with the ac
current calibration.
The ac current calibration uses a number of current shunts that are necessary for
dc characterization before they can be used. DC characterization can be done
with the Product, if you do the full dc current calibration first. When you do a dc
characterization, data is obtained for each of the ac current levels needed by the
ac current calibration procedure. For example, if a shunt is used for 0.33 mA ac
and 3.3 mA ac calibrations, data must be obtained at 0.33 mA dc and 3.3 mA dc.
To characterize the shunt:
1. Connect the test equipment as shown in Figure 13.
UUT
5790A or 5790B
5790A
AC MEASUREMENT
STANDARD
1000V RMS MAX 1000V RMS MAX
3V RMS MAX
INPUT 1 INPUT 2
SHUNT
HI
LO
GUARDGROUND
SHELL FLOATING
10V PEAK
MAX
WIDEBAND
7V RMS MAX
MAX
10V PK
SHELL FLOATING
792-7004
Current
shunt
adapter
A40 shunt
Set 5790A or
5790B to external guard
Guard to Aux Lo Terminal
gru007.eps
Figure 13. Connections for Calibrating AC Current with a Fluke A40 Shunt
2. For each amplitude shown in Table 36, apply the equivalent +(positive) and -
(negative) dc current from the Product.
3. Calculate the actual dc characterization value with this formula:
((+Value)
(-Value))
2
The time between the dc characterization of a current shunt and the start
calibration should be kept to a minimum. To decrease this time, each shunt is
characterized as it is needed. As the ac current calibration procedure is done, it
must be temporarily aborted each time a new shunt value is necessary. After the
necessary shunt is characterized, the calibration procedure is continued at the
previous point with the newly characterized shunt.
The example that follows demonstrates this procedure:
1. Do the dc current calibration procedure.
2. Select the first current shunt (A40-10 mA) shown in Table 36.
3. Do a dc characterization of the shunt at the amplitude specified in the table
(as demonstrated above).
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