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The 120V output waveform of the Evolution series inverters is a pure sine wave like the wave-
form of the grid power. Please see sine waveform represented in the Fig. 1.1 that also shows
equivalent modified 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 modified sine wave, the voltage
rises and falls abruptly, the phase angle also changes abruptly and it sits at 0V 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 voltage crossing (for timing control) will not
work properly from a voltage that has a modified sine waveform.
Also, as the modified 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 modified sine wave. For
example, a 60 Hz modified sine wave will consist of sine waves with odd harmonic frequencies
of 3rd (180 Hz), 5th (300 Hz), 7th (420 Hz) and so on. The high frequency harmonic content in
a modified sine wave produces enhanced radio interference, higher heating effect in inductive
loads like microwaves and motor driven devices like hand tools, refrigeration / air-conditioning
compressors, pumps etc. The higher frequency harmonics also produce overloading effect in
low frequency capacitors due to lowering of their capacitive reactance by the higher harmonic
frequencies. These capacitors are used in ballasts for fluorescent lighting for Power Factor
improvement and in single-phase induction motors as start and run capacitors. Thus, modified
and square wave inverters may shut down due to overload when powering these devices.
1.3.2 Advantages of Pure Sine Wave Inverters
•
The output waveform is a sine wave with very low harmonic distortion and cleaner power like
utility supplied electricity.
•
Inductive loads like microwaves, motors, transformers etc. run faster, quieter and cooler.
•
More suitable for powering fluorescent lighting fixtures containing power factor improvement
capacitors and single phase motors containing start and run capacitors.
•
Reduces audible and electrical noise in fans, fluorescent lights, audio amplifiers, TV, fax and
answering machines.
•
Does not contribute to the possibility of crashes in computers, weird print outs and glitches in
monitors.
Some examples of devices that may not work properly with modified sine wave and
may also get damaged are given below:
•
Laser printers, photocopiers, and magneto-optical hard drives.
•
Built-in clocks in devices such as clock radios, alarm clocks, coffee makers, bread-makers,
VCR, microwave ovens etc. may not keep time correctly.
•
Output voltage control devices like dimmers, ceiling fan / motor speed control may not work
properly (dimming / speed control may not function).
•
Sewing machines with speed / microprocessor control.
•
Transformer-less capacitive input powered devices like (i) Razors, flashlights, night-lights,
smoke detectors etc. (ii) Re-chargers for battery packs used in hand power tools.
These may
get damaged. Please check with the manufacturer of these types of devices for suitability.
SECTION 1 |
Safety Instructions & General Information
Summary of Contents for Evolution EVO-2212
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