PSM3750 Quick User Guide
Page 48
8.2 PAV
–
Phase Angle Voltmeter
A phase angle voltmeter (or vector voltmeter, or phase sensitive voltmeter)
measures the signal at one input compared to the magnitude + phase of the
signal at a reference input. The results may be expressed as magnitude and
phase, or as separate in-phase and quadrature components.
The PSM3750 measures the in-phase and quadrature components at the
fundamental frequency using DFT analysis as described in the section on
frequency response analysis. CH2, the measurement input, is phase referred to
CH1, the reference input. The individual components are filtered separately to
minimise the effects of noise, which would have random phase and would
therefore be filtered out. The true rms of the input signals is also computed.
CH1 and CH2 may be voltage inputs or may use external shunts.
From the phase referred fundamental components, (a + jb), the following results
can be derived:
magnitude =
(a
2
+ b
2
)
phase
= tan
-1
(b/a)
tan
= b/a
in-phase ratio = a2 / a1
LVDT (diff) = scale * a2 / a1
LVDT (ratio) = scale * (m1-m2) / (m1+m2)
Where a1 and a2 are the in-phase components, and m1 and m2 are the
magnitudes, of the signals present at ch1 and ch2 respectively.
The parameter of interest is selected via the PAV or MODE menu. The frequency
and phase are always displayed.
Summary of Contents for PSM3750 NumetriQ
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