OT a bit - matching UPS with one's pc

On Wednesday, June 12, 2013 10:44:12 PM UTC-4, miso wrote:
The double conversion scheme is a power conditioner and UPS at the same
time. If you understand electronics, it is far easier to absorb a surge
at DC versus AC.

How many power supplies have you designed? Anything done by the power conditioner is routinely done inside all electronics. For example, how does that '****ty' power become the rock solid 3, 5, and 12 volt DC. All ****ty power is first converted to well over 300 volts. And then converted to higher voltage radio wave spikes. Does not matter how 'clean' that UPS power is. Because inside all electronics, the power is then made much 'dirtier'..

What happens next? Those many hundred volt spikes are converted to rock solid 3, 5, or 12 volts DC by superior power conditioners already inside all electronics.

Why spend so much money on a $1000 UPS when all that 'cleaning' is automatically undone inside all electronics? Many have fears rather than learn how electronics work. Those fears get the naive to recommend a $1000 UPS rather than the $100 one.

If 'dirty' UPS power is harmful, then you can cite each specific part inside an appliance damaged by 'dirty' power. If you cannot, then knowledge comes from advertising and hearsay; not from designing electronics.

'Dirty' UPS power is ideal for all electronics. However is can be harmful to less robust devices such as small electric motors and power strip protectors.

Cure the problem. Spending excessively on a double conversion UPS solves what problem? Averts damage to what part? Making subjective claims about '****ty' power is why advertising is so profitable. What a double conversion UPS might do is already done better inside electronic appliances. Now reread those numbers. Any cleaning by a UPS is first completely undone inside electronics. And then ‘cleaned’ by superior circuits already inside each appliance.

On 6/12/2013 10:44 PM, miso wrote:
The double conversion scheme is a power conditioner and UPS at the same
time. If you understand electronics, it is far easier to absorb a surge at
DC versus AC.

Seriously, those modified sine wave UPSs are so ****ty it is far better to
suffer a power outage.

Look at the modified sine waveform. It is more like a modified square wave.
The steep edges will stress the power supply since i=C*DV/DT, and the DV/DT
of a square wave is infinite. Of course the modified sine doesn't have an
infinitely fast rise time, but it is faster than the design criteria of
2*pi_60Hz.


If one has a conservatively designed computer then the modified sine wave
you so fear is not a problem at all. This is especially true since it is
powering the computer for very short periods of time. As a Unix sysadmin
I've been down the road with the high-priced always-on sine wave UPS units
such as the big Toshibas and know that for the home user who suffers a few
minutes of outage every month such a thing would be throwing money away.
Doubly so since the always-on units are fairly greedy consumers of power on
their own.

I have five of the sort of UPS units you preach against and have had them
for years and from several manufacturers. I have fairly frequent short-term
power failures and occasional brownouts. I have had zero power supply
failures during this period of use. If they were as dangerous as you say,
shouldn't I have had at least one computer going up in smoke?