Arbiter Systems 931A, Operation Manual

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value measured by measurement Channel 1. The large number below it
corresponds to the voltage value for measurement Channel 2.
The display indicates the general measurement bandwidth near the
lower left-hand corner. The Model 931A uses either wide-band or narrow-
band mode to measure and display AC voltage.
Press the SHIFT key then BAND-WIDE to change the measurement
mode to wide-band RMS and include all frequencies up to 3.05 kHz.
Press the SHIFT key then NARROW-BAND to measure the fundamental
magnitude only, using DSP algorithms; harmonics are ignored.
The Model 931A displays dashes for Channel 1 and Channel 2, when
in narrow-band mode, if the signal present on Channel 1 is below a value,
which can be accurately measured.
NOTE: Channel 1 is used as the internal reference; if only one
signal is measured, Channel 1 must be used. If both a current
and a voltage are measured, Channel 1 should be used for the
voltage and Channel 2 for the current.
3.5.2 AC Current Measurement
The Model 931A can directly measure and display AC currents of up to
20 Arms.
It can measure higher currents using a current transformer
(CT) and with direct readout using the scaling feature (see “Scale” in
Section 3.3.2.17).
3.5.2.1 Input Connections
The Model 931A provides three sets of input connectors for measuring AC
current: labeled “A”, “B”, and “C”. All three inputs use identical circuitry
and are electrically isolated from all others: the voltage inputs, and chassis
ground. The input multiplexing circuitry allows measurement of the value
at any one the inputs. The Neutral Current,
In =
−
( Ia + Ib + Ic ), is
available for measurement on Channel 2.
3.5.2.2 Configuring the Channel
Configure the chosen measurement channel after connecting the current
to the appropriate input terminals. If measuring only one AC current
(e.g. single-phase), use Channel 1, since this channel is used for frequency
measurements.
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