Newtons4th N4L PPA500/1500 User Manual

PPA5xx/15xx user manual
9-12
9.4 Phase to phase computations
In 3 phase 3 wattmeter configuration, the voltmeters are
connected across each individual phase and neutral. The
phase to phase voltages are synthesised from the
individual phase data:
display phase
computation
phase 1
phase 1 – phase 2
phase 2
phase 2 – phase 3
phase 3
phase 3 – phase 1
Phase to phase values are computed for rms, fundamental
magnitude and phase.
Consider the fundamental component:
V
12
(t) = V
1
(t) – V
2
(t)
= V
1
sin(ωt) – V
2
sin(ωt + φ
12
)
= V
1
sin(ωt) – V
2
[sin(ωt).cos(φ
12
) + cos(ωt).sin(φ
12
)]
= sin(ωt) [V
1
– V
2
cos(φ
12
)] - V
2
cos(ωt).sin(φ
12
)
In a balanced system:
V
1
= V, V
2
= V and φ
12
= 120˚
V
12
= sin(ωt) [V – V cos(120˚)] + V cos(ωt).sin(120˚)
= 1.5 V sin(ωt) - √3/2 V cos(ωt)
= √3 V sin(ωt – 30˚)
So, the phase to phase voltage would have a magnitude
√3 times larger than the phase to neutral voltage at a
phase displacement of -30˚.
The PPA5xx/15xx applies the computations in a general
way without any assumptions about the system. It,
therefore, computes the correct values whatever the
waveform.

Newtons4th N4L PPA500/1500 Specifications

General

Brand	Newtons4th
Model	N4L PPA500/1500
Category	Measuring Instruments
Language	English