SamplexPower Pure Sine Wave PST-600-12 Manuel Du Propriétaire page 10

SECTION 2 |
2.2 OUTPUT VOLTAGE WAVEFORMS
180
160
140
120
100
80
60
40
20
0
20
Pure Sine Wave
40
crosses Zero Volt
60
instantaneously
80
100
120
140
160
180
TIME
Fig. 2.1: Pure and Modifi ed Sine Waveforms for 120 VAC, 60 Hz
also shows Modifi ed Sine Waveform for comparison.
In a Sine Wave, the voltage rises and falls smoothly with a smoothly changing phase
angle and also changes its polarity instantly when it crosses 0 Volts. In a Modifi ed Sine
Wave, the voltage rises and falls abruptly, the phase angle also changes abruptly and
it sits at zero V for some time before changing its polarity. Thus, any device that uses a
control circuitry that senses the phase (for voltage / speed control) or instantaneous zero
Modifi ed Sine Waveform.
Also, as the Modifi ed Sine Wave is a form of Square Wave, it is comprised of multiple
Sine Waves of odd harmonics (multiples) of the fundamental frequency of the Modifi ed
frequency harmonic content in a Modifi ed Sine Wave produces enhanced radio interfer-
frequency harmonics also produce overloading effect in low frequency capacitors due to
lowering of their capacitive reactance by the higher harmonic frequencies. These capaci-
tors are used in ballasts for fl uorescent lighting for Power Factor improvement and in
single-phase induction motors as Start and Run Capacitors. Thus, Modifi ed and Square
Wave inverters may shut down due to overload when powering these devices.
10 | SAMLEX AMERICA INC.
General Information
V = 169.68V
PEAK
V = 140 to 160V
PEAK
V = 120 VAC
RMS
Modified Sine
Wave sits at
ZERO for some
time and then
rises or falls
16.66 ms
Sine Wave
Modified Sine Wave