Waveform and harmonics – GE EPM 5200 User Manual
Page 8
CHAPTER 1: AC POWER MEASUREMENT
4
EPM 5000 series Advanced Power Meters GE Multilin
1.4: Waveform and Harmonics
Ideal power distribution has sinusoidal waveforms on voltages and currents. In real-life applications,
where inverters, computers, and motor controls are used, distorted waveforms are generated. These
distortions consist of harmonics of the fundamental frequency.
SINUSOIDAL WAVEFORM:
t)
(
sin
•
A
⋅
ω
DISTORTED WAVEFORM:
L
+
t)
•
sin(
•
A
+
t)
•
sin(
•
A
+
t)
•
sin(
•
A
+
t)
•
sin(
•
A
3
3
2
2
1
1
ω
ω
ω
ω
TOTAL HARMONIC DISTORTION (THD):
100
Signal
l
Fundamenta
the
of
RMS
Signal
Distortion
Harmonic
Total
of
RMS
=
THD
of
%
×
HARMONIC DISTORTION: A destructive force in power distribution systems. It creates safety problems,
shortens the life span of distribution transformers, and interferes with the operation of electronic devices.
The Futura+ monitors the harmonic distortion to the 31st harmonic. A waveform capture of distorted
waveform is also available.
% THD GRAPH