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Yeah, right.
That boy needs to consult somebody with a B.S. in electrical science instead of all this - - - he said - she said.
I just confirmed my facts with my old high school buddy who DOES have a B.S. in Electrical Engineering and IS the head of diagnostic and service for ALL scientific instrumentation at a major Texas University
(His wizard lab is full of oscilliscopes showing waveforms, etc on screen).
He said indeed that modified sine wave may be OK for temporary outages, but he would not want any of his computers running off modified sine wave 24/7/365 (like off an inverter).
Now I'll sleep at night knowing I got "the real deal".
Also, if you have any Cisco router equip. powered off a modified sine wave device you are "playing with fire" as Cisco devices incorporate the more sensitive active power-factor correction (PFC)circuitry.
Q: How important is "true sinewave" compared to "stepped sinewave"?
Very important. Solid State devices such as microprocessors are very sensitive to voltage fluctuations and electrical noise. The amount of electrical noise produced by a UPS is expressed as the UPS wave form's Total Harmonic Distortion or THD. Electrical noise is actually an unwanted voltage at odd multiples of the 50 Hz fundamental frequency, such as the 3rd harmonic (150 Hz), 5th harmonic (250 Hz), and so forth. A Stepped wave (modified sine wave) UPS has a THD of greater than 28%, meaning that the UPS produces unwanted voltages (electrical noise contributions) at 150 Hz, 250 Hz, 350 Hz, and so forth, that feed into your equipment from the UPS, that reach nearly 1/3 or more of the magnitude of the voltage supplied at 50 Hz! This negatively affects solid state equipment, and even affects computer power supplies under many common conditions.
There are many other reasons why a stepped wave output is unacceptable today for use with computer equipment, one reason alone being that it leads to advanced deterioration of filtering or surge circuits present in most PC power Supplies. The Transfer Time is also very important in some instances. Your equipment must be able to "ride through" the amount of time it takes for the UPS to "transfer to and from battery". A PC power supply can usually easily do this, because it contains float capacitors, but some solid state equipment cannot do this. We recommend True Online UPS Systems (pure sine wave) for this reason.
>From another source: "Modified sinewave inverters will produce a level of interference in the computer monitor generally seen as small lines across the monitor and a small hum in the speakers". Hmmmmmm . . . that sounds like voodoo harmonics _-- again.
Here's some technical articles that you can update your cranium with:
https://ssl-001.9netave.com/~ux243077/doctext/upscho.htm
http://inet-access.net/pipermail/list/2003-August/000164.html
John
On Thu, 20 Nov 2003 14:58:59 -0600 , Jimmy Snowden <jhsnowden@xxxxxxx> wrote:
>Ya can't put it on a Bass Boat, it'll swamp that end of the boat.
>Let's leave the boy alone. He got had by a salesman and just can't
>stand it. You can put a big battery on any UPS, but it will sink the
>Bass Boat if you do.
>
>Best regards,
> Jimmy Snowden
>mailto:jhsnowden@xxxxxxx
>
>
>Thursday, November 20, 2003, 2:54:46 PM, you wrote:
>
>D> But how fast will it spin the prop on your bass boat? Let's get our
>D> priorities straight here folks!
>
>
>
>
>Outgoing mail scanned by Norton
>
>
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