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3.6 Range Selection
The ohmmeter is designed to automatically start up in Auto-Range. According to the
load the instrument will automatically select the range that will display the measurement
with the greatest resolution possible. While in auto range, the display range window will
show “AUTO”. In many applications where the test current is critical, the user can
manually select a range.
Figure 15 - Range Key Pad
Ranges are easily selected by pressing the appropriate key. The range keys are labeled
using the value of the range and the respective test current value. The range selected will
be displayed on the range window. To return to the auto range mode, press the
“
A
UTO
R
NG
”
key on the front panel.
3.7 Overload and Safe Mode
When the value of the load exceeds the range limit, the instrument will be in an
Overload
state. In cases of overload, the display will repeatedly flash the word “OVERLOAD”. If
this occurs, select a higher range setting or press the Auto key so that the instrument can
automatically select the appropriate range. If the load value exceeds the limit of the
highest range, promptly disconnect the load from the instrument to avoid damage to the
equipment.
As a safety precaution, the 4176 is designed to switch into Safe Mode if the overload
persists for more then 10 seconds. In safe mode the 4176 shuts down its current source,
and displays the word “SAFEMODE” the screen. The ohmmeter does not automatically
recover from safe mode; the user must press the Enter key to return to measurement
mode. This is so that the user can be aware that an overload has occurred, so that the
cause maybe investigated if necessary.
