Vanguard Auto-Ohm - Manual (Page 10)

Auto-Ohm Operating Procedures
6
6.0 OPERATING THE AUTO-OHM
(See Figure 3. for step-by-step procedures.)
The Auto-Ohm is operated by just one dual-
function control knob. The operator turns
the control knob to scroll through different
menu selections on the display. When the
desired option appears, it is selected by
simply pressing the control knob like a
pushbutton. Review Figure 3 before
proceeding with the step-by-step procedures
that follow.
6.1 STEP-BY-STEP PROCEDURES
6.1.1 Precautions
CAUTION
Do not measure resistance of
inductive devices, which can create
unsafe high-voltage spikes if the test
current is interrupted by a detached
test lead (created by collapsing
magnetic field). Do not touch or
disconnect any test lead that is
connected to a device under test
while current is being conducted.
Failure to heed this warning can
result in damage to the Auto-Ohm.
The Auto-Ohm measures low, non-
inductive resistances (e.g., breaker
contacts and bus-bar junctions); If
the resistance of an inductive device
is desired, the use of an Instruments
designed for that purpose is
recommended (such as the Accutrans
made by the Vanguard Instruments
Company).
6.1.2 Preparations
a. Plug the Auto-Ohm power cable into a
power outlet.
b. Insert current-cable plugs and voltage-
sensing cable plugs into respective control-
panel jacks (Figure 2). Ensure that voltage
plugs are inserted into jacks adjacent to
companion current jacks.
c. Attach test-cable clamps to opposite
terminals of the resistive load being tested.
d. To turn on Auto-Ohm power, press the
rocker switch to ON (item 1 in Figure 1).
NOTE
All Auto-Ohm operations begin at the
MAIN MENU, which appears after the
initial boot-up (after configuration and
software revision data display briefly.) The
Main Menu display is shown below:
Figure 4. Main Menu
e. The main menu displays a list of four
options, which appear in sequence as the
control knob is turned. The four functions
of the Main-Menu list are:
RUN TEST, ADJ
CONTRAST, 100A CAL. CHECK, and
PREVIOUS RESULTS.
f. When the option of choice appears in the
Main Menu, press (or “Push”) the control
knob to enter the selection and start that
sequence. The step-by-step operating
procedures to follow describe each of the
selected options in the order listed above. To
run a test, turn the control knob until RUN
TEST appears on the display, then press the
control knob to begin the procedures for
running a test.
6.1.3 Run Test Procedure
The display (SELECT TEST CURRENT)
will appear to the user after the user presses
control knob from the RUN TEST menu,
(Figure 4).
Figure 5. Select 10A Menu
MAIN MENU
SELECT TEST CUR
<10 AMPS>