User manual

Front Panel Operation
3-34 2001-900-01 Rev. K/ August 2010
A procedure to measure in-circuit current follows:
1. Select the in-circuit current measurement mode from the
CONFIGURE DCI menu and place the instrument in
the DCI function. Note that the 4W annunciator lights to
indicate this is a 4-wire measurement.
2. Connect a set of Kelvin test probes, such as Keithley
Model 5805 or 5806, to the Model 2001 INPUT HI and
LO terminals and SENSE HI and LO terminals.
3. For R
TRACE
<50m, or where the conductors are physi-
cally hot, rel out (zero correct) any thermal offsets that
are present before measuring in-circuit current. With
power to the test circuit removed, place the probes on
the desired trace and enable rel from the DCI function.
4. Turn on the power to the test circuit and read the in-cir-
cuit current calculation. The speed of this measurement
is four readings per second at 1PLC. Its range is fixed at
12A. The default filter for in-circuit current is a moving
average of ten readings. Additional filtering may be
needed at low voltage levels.
COUPLING
This parameter selects the input coupling for the ACI
function. When AC coupling is selected, a DC blocking
capacitor is placed in series with the AC measurement
circuit. (Note that the current shunt resistors are always DC
coupled to the inputs.) This removes the DC component
from the RMS and average ACI measurement.
When AC+DC coupling is selected, the blocking capacitor is
removed. Subsequent RMS or average ACI measurements
will reflect both the AC and DC components of the signal.
You can set the ACI coupling as follows:
1. From the CONFIGURE ACI menu, select COUPLING
and press ENTER. The following menu is displayed:
SET AC COUPLING
AC AC+DC
2. Highlight the desired coupling and press ENTER.
Note that the coupling settings for ACI and ACV are
discrete. Thus, setting the coupling of ACI has no effect on
the coupling of ACV.
AC-TYPE
This parameter selects the measurement type for the ACI
function. The Model 2001 directly measures RMS and
average AC current. You can program the ACI type
parameter as follows:
1. From the CONFIGURE ACI menu, select AC-TYPE
and press ENTER. The following menu is displayed:
SET ACI MEASUREMENT
RMS AVERAGE
2. Highlight the desired measurement type and press EN-
TER.
With this parameter selected, the instrument performs
RMS AC current measurements.
When this item is selected, the signal path in
the instrument bypasses the RMS converter, so the average
ACI measurement is just the filtered output of a full wave
rectifier.
Multiple displays
The multiple displays for AC current that show multiple
functions are shown in Figure 3-13. There are no
multifunction displays for DC current.