Arbiter Systems 931A, Operation Manual

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3.4 Front Panel Display
The Model 931A uses a supertwist liquid-crystal display with a resolution
of 240 horizontal pixels by 64 vertical pixels. In most cases, both mea-
surement channels simultaneously display information from measurements
and some instrument configuration.
The display has a bright CCFL backlight available for low ambient
light situations. See Section 3.3.1.13 Menu, Backlight and Auto-shutdown
control, for directions on using the backlight.
Use of the backlight
significantly increases the battery drain.
Display changes in response to keystrokes allow selections from multiple
menu levels, resulting in a self-prompting interface.
3.5 Direct Measurements
For measurement of certain parameters, the Model 931A computes results
from one or both channels individually. Always use Channel 1 if only
one input signal is present. These measurement parameters include the
following:
ˆ
AC Voltage
ˆ
AC Current
ˆ
DC Voltage
ˆ
Frequency
ˆ
Harmonics
ˆ
Waveform
The following sections provide instructions for performing measure-
ments of parameters within this group.
3.5.1 AC Voltage Measurement
The Model 931A can measure and display AC voltages of up to 750 Vrms.
3.5.1.1 Input Connections
Four inputs, labeled “A”, “B”, “C”, and “N” are available for measuring
AC voltage, and each uses identical circuitry. Input multiplexing circuitry
allows measurement of the value at inputs “A”, “B”, or “C”, relative to
any other input. For example, to measure a voltage between terminals
“A” and “N” simply connect the leads to those two terminals.
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