VAMP 260 - RMS Values; Total Harmonic Distortion (THD); Voltage Sags and Swells

VAMP 260 Power monitoring unit
Technical description
VAMP Ltd
12
Vamp 24h support phone : +358 (0)20 753 3264
VM260.EN004
2.2.6. Total harmonic distortion (THD)
The unit calculates the THDs as percentage of the base
frequency for currents and voltages.
The unit calculates the harmonics for phase currents and phase
voltages from the 2nd to the 15th order.
(The 17
th
harmonic component will also be shown partly in the
value of the 15
th
harmonic component. This is due to the nature
of digital sampling.)
The formula below applies similarly to voltage calculation:
%100
...
1
2
15
2
3
2
2
⋅
+++
=
f
fff
I
III
THD
2.2.7. RMS values
RMS currents
PMU calculates the RMS value of each phase current. The
minimum and the maximum of RMS values are recorded and
stored (see chapter 2.2.12).
2
15
2
2
2
1
...
fffrms
IIII +++=
RMS voltages
PMU calculates the RMS value of each voltage input. The
minimum and the maximum of RMS values are recorded and
stored (see chapter 2.2.12).
2
15
2
2
2
1
...
fffrms
UUUU +++=
Apparent RMS power (S
RMS
)
PMU calculates the RMS value of apparent power (S). The
minimum and the maximum of RMS values are recorded and
stored (see chapter 2.2.12).
S
rms
= I
rms *
U
rms
2.2.8. Voltage sags and swells
The power quality of electrical networks has become
increasingly important. The sophisticated loads (e.g. computers
etc.) require uninterruptible supply of “clean” electricity. VAMP
protection platform provides many power quality functions that
can be used to evaluate, monitor and alarm on the basis of the
quality. One of the most important power quality functions are
sag monitoring and swell monitoring.
VAMP provides separate monitoring logs for sags and swells.
The voltage log is trigg, if any voltage input either decreases