Good, quasi-square wave UPS?

A

AC/DCdude17

Guest
I have a Belkin 350VA UPS with a quasi square wave output. Its output
works ok for my computer, but it doesn't work well all with non switching
power supply load. An incandescent lamp flickers badly. A fluorescent
lighting with inductive input(magnetic ballast or commercial grade
electronic) causes the ballast and UPS to make a noise that sounds like
resonating and flickers very badly. The output waveform is very elastic
and it jumps around on the scope screen.

The output waveform on my 300W quasi squarewave inverter is much rigid
and it has no problem running non-switching power supply loads.

Is there a quasi-square wave UPS that can at least stably power anything
my power inverter can?

By the way, there is a dead obvious difference in the inverter circuit
between the two. The power inverter uses a few ferrite core high
frequency transformers. The Belkin UPS have a low frequency steel core
transformer that is used for both charging and inverter transformer.
 
in article MPG.19c165d8574076b7989692@news.verizon.net, AC/DCdude17 at
JerC@prontoREMOVETHISmail.com wrote on 9/4/03 4:10 PM:

I have a Belkin 350VA UPS with a quasi square wave output. Its output
works ok for my computer, but it doesn't work well all with non switching
power supply load. An incandescent lamp flickers badly. A fluorescent
lighting with inductive input(magnetic ballast or commercial grade
electronic) causes the ballast and UPS to make a noise that sounds like
resonating and flickers very badly. The output waveform is very elastic
and it jumps around on the scope screen.

The output waveform on my 300W quasi squarewave inverter is much rigid
and it has no problem running non-switching power supply loads.

Is there a quasi-square wave UPS that can at least stably power anything
my power inverter can?

By the way, there is a dead obvious difference in the inverter circuit
between the two. The power inverter uses a few ferrite core high
frequency transformers. The Belkin UPS have a low frequency steel core
transformer that is used for both charging and inverter transformer.


You didn't specify the waveform very well. You could try using a low pass
Click to expand...
filter that cuts out harmonics. If the waveform is symmetrical + & -, the
first significant harmonic will be the third or 180 Hz. I would think that
the criterion will be cost.

There are companies in the business of filtering harmonics.

Bill
 
Most iron-core transformer inverters don't work well with inductive or high
power factor loads. This isn't a limited to small inverters. Some of the big
switching power supplies (Cisco routers and switches) specifically mention that
they should not be run from certain classes of inverters because of the
inverter's inability to handle the switching supply load. The 40KVA UPS at the
network lab I worked in a couple of years ago provided a modified sine wave
output. The UPS used 400+ volts of NiMH cells as the power source until the
backup diesel generators could be started and take the load.

If you buy better equipment (stepped sine wave or sine wave), then the waveform
is better and the ability to handle non-resistive loads improves greatly. Of
course, you will pay several times more per watt of output than you do for the
simple inverters.

I use small UPS's (including a Belkin 350) for graceful desktop PC shutdown and
an APC 180 for the local network (DSL modem, router, switch). The APC provides
over an hour of run time for the network equipment. Rechargeable power failure
lights provide immediate light during short power outages (plus battery powered
lanterns) and oil lamps plus a Coleman lantern handle longer outages.

If really pressed for power, I have a small inverter that can be powered from a
12 volt vehicle.

AC/DCdude17 <JerC@prontoREMOVETHISmail.com> wrote:

I have a Belkin 350VA UPS with a quasi square wave output. Its output
works ok for my computer, but it doesn't work well all with non switching
power supply load. An incandescent lamp flickers badly. A fluorescent
lighting with inductive input(magnetic ballast or commercial grade
electronic) causes the ballast and UPS to make a noise that sounds like
resonating and flickers very badly. The output waveform is very elastic
and it jumps around on the scope screen.

The output waveform on my 300W quasi squarewave inverter is much rigid
and it has no problem running non-switching power supply loads.

Is there a quasi-square wave UPS that can at least stably power anything
my power inverter can?

By the way, there is a dead obvious difference in the inverter circuit
between the two. The power inverter uses a few ferrite core high
frequency transformers. The Belkin UPS have a low frequency steel core
transformer that is used for both charging and inverter transformer.
Click to expand...
More about me: http://thelabwiz.home.mindspring.com/
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AC/DCdude17 <JerC@prontoREMOVETHISmail.com> wrote:

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the Wiz wrote:

Most iron-core transformer inverters don't work well with inductive or high
power factor loads. This isn't a limited to small inverters. Some of the big
switching power supplies (Cisco routers and switches) specifically mention that
they should not be run from certain classes of inverters because of the
inverter's inability to handle the switching supply load.

The Belkin 350VA won't power an incandescent lamp stably(flickers badly). The only things that
operates stably are low power factor switching power supply loads such as residential grade CFLs and
computers.
Click to expand...
Interesting problem. My Belkin 350VA has a slight intermittent flicker in the
first 20 seconds or so of powering a 40 watt incandescent bulb (only available
lamp for testing - the UPS is w-a-y under the desk), but then the power is
stable.

More about me: http://thelabwiz.home.mindspring.com/
VB3 source code: http://thelabwiz.home.mindspring.com/vbsource.html
VB6 source code: http://thelabwiz.home.mindspring.com/vb6source.html
VB6 - MySQL how to: http://thelabwiz.home.mindspring.com/mysql.html
My newest language - NSBasic for the Palm PDA: http://thelabwiz.home.mindspring.com/nsbsource.html
Drivers for Pablo graphics tablet and JamCam cameras: http://home.earthlink.net/~mwbt/
johnecarter atat mindspring dotdot com. Fix the obvious to reply by email.
 
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