Choosing Delta Units; Establishing A Reference - Fluke 5790B/3 Operator's Manual

2. Connect a Model A40 (not A40A) Current Shunt to the adapter.
3. Connect the current shunt to the ac current source under test.
4. Press the [INPUT1] key so that its keycap indicator lights.
5. Select continuous trigger (EX TRIG keycap indicator off.)
6. The displays show readings up to 700 mV.
7. Apply the reference dc current to the current shunt and store the reference as
described under "Instructions for Transfer Mode".
8. Reverse the polarity of the reference current and press the softkey to average the
reference as described under "Instructions for Transfer Mode".
9. Apply the ac current under test. Transfer results are continuously updated on the
Control Display.

4-26. Choosing Delta Units

During transfers, the Control Display shows the difference between an applied input and
the stored reference, or average of references. The difference can be displayed in units of
V (or mV), ppm, percent, or ratio. Once a reference has been established you cycle
though each choice by pressing any of the three softkeys showing on the Control Display.
The Control Display cycles through PPM, PCT, VOLTS, and RATIO, and displays the
equation used in each case.

4-27. Establishing a Reference

As an example, apply an external dc reference to INPUT 2. For highest resolution and
most stable measurement display, set the Digital Filter to SLOW. (Press [UTIL MENUS]
and "Meas Control" to access the Digital Filter controls.) If the wait for a settled reading
("U" annunciator off) is too long, adjust the digital filter speed and/or restart threshold.
The displays appear as follows for a typical dc calibrator set to +2 V dc:
Press the "Set Ref" softkey to establish the present input level as a reference. The
Displays appear as follows:
+
+
Front Panel Operation
Instructions for Transfer Mode
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