Ac Current Calibration - Fluke 5520A Service Manual

5520A
Service Manual

3-10. AC Current Calibration

DC Current must be calibrated before proceeding with ac current calibration.
The ac current calibration uses a number of current shunts that require dc characterization
before they can used. DC characterization can be performed with the 5520A, as long as
you perform the entire 5520A dc current calibration first. During dc characterization, data
is obtained for each of the ac current levels required by the ac current calibration
procedure. For example, if a shunt is used for .33 mA ac and 3.3 mA ac calibrations, data
must be obtained at .33 mA dc and 3.3 mA dc.
Follow these steps to characterize the shunt:
1. Connect the test equipment as shown in Figure 3-7.
INPUT 1
1000V RMS MAX
SHELL FLOATING
WIDEBAND
7V RMS MAX
SHELL FLOATING
Set 5790A to
external guard
2. For each amplitude listed in Table 3-11, apply the equivalent +(positive) and
3. Compute the actual dc characterization value using this formula:
The time between the dc characterization of a current shunt and its use in the calibration
process should be kept to an absolute minimum. To reduce this time, each shunt is
characterized as it is needed. As the ac current calibration procedure is performed, it must
be temporarily aborted each time a new shunt value is required. After the required shunt
is characterized, the calibration procedure is resumed at the previous point using the
newly characterized shunt.
The following example explains this procedure:
1. Perform the dc current calibration procedure.
2. Using Table 3-11, select the first required current shunt (A40-10 mA)
3-14
5790A
5790A AC MEASUREMENT
792-7004
STANDARD
Current
shunt
adapter
INPUT 2
1000V RMS MAX
HI
SHUNT
3V RMS MAX
LO
10V PEAK
MAX
GROUND GUARD
10V PK
MAX
Figure 3-7. Connections for Calibrating AC Current with a Fluke A40 Shunt
- (negative) dc current from the 5520A.
((+ value) - (- value))
2
Note
A40 shunt
UUT
5520A CALIBRATOR
NORMAL AUX
SCOPE
V, , ,RTD
A, -SENSE, AUX V
OUT
HI
1000V 20V
1V PK
RMS RMS
MAX
MAX MAX
150V
LO
PK
MAX
TRIG
20V
RMS
MAX
20V
PK
20A SHELLS
GUARD
NOT MAX
GROUNDED
20V PK MAX TC 20V PK MAX
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