PSM1700 PsimetriQ user manual
12-1
12 Phase angle voltmeter (vector voltmeter)
A phase angle voltmeter (or vector voltmeter, or phase
sensitive voltmeter) measures the signal at one input
compared to the 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.
PsimetriQ 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.
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