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February 8, 2013 - 1:11pm
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Whole house AC power - Inverter vs. UPS
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I live in a desert area that for some reason seems to get several power interruptions per month at times, plus we get thunderstorms in July and August that knock it out.
I have an APC 1500 VA UPS unit for my computer, and another one for the TV and amplifier etc.and another one for the high-end stereo gear in the living room. They cost around $250 each, plus a few bucks every 5 years or so for a new battery for each one, but it is well worth it to protect my gear. I have never had any electronic gear fail in all that time.
The one thing I do not plug into them is my large power amplifiers, which draw quite a lot of current and are pretty insensitive to surges.
They give me a minimum of 15 minutes to shut things down if power does not come back on quickly. They have never failed to protect all of my gear in the 15 years or so that I have used them.
Thanks commsysman, but that's not what I'm asking. Options seem to be
The delay when an invertor kicks in can be as short as 6 milliseconds. I can't find anybody who knows whether that is a short enough "outage" to prevent damage to sensitive electronics, including computers but mostly AV equipment. If the answer is yes, that's probably the best approach for me. If not, I'll need to go with a UPS configuration.
Well, the APC UPS units I am using HAVE protected all of my sensitive elctronics at two homes for over 20 years. I know a lot of other people who have had MANY equipment failures, while I have had NONE. I think that a very large percentage of electronic gear failures are due to surge damage (and often people don't realize it because failure is not always immediate).
The 1500 VA units cost around $250 each, and then $60 each for new battery every 5 years or so. I consider this dirt cheap, since I have over $30,000 invested in my gear.
How many units you need depends on where your gear is located and other factors. I need one for each desktop computer, and one for each stereo or AV system.
The other alternatives do not seem viable to me, but I guess that is a matter of opinion and economics.
By the way; It is not mandatory to have pure sine-wave backup power when a unit has a power transformer. The power transformer's inductance smooths the waveform to a sine wave anyway (and we are only talking about a short time while you shut down the equipment). Besides, the output of the transformer goes to filter capacitors anyway and becomes DC.
Backup power for extended outages is not an issue for me. If the power is not back on after one minute, I shut it all down just to be safe. My backup units will probably give me at least 10 minutes, but if there is a nasty surge later I want it off anyway.
I am confused by your use of the word "inverter'. An inverter converts DC to AC. An inverter is used when the whole house is being run by wind or solar power, which charge batteries. The inverter then converts the DC battery power to AC as needed.
Of course you could install 30 or 40 large batteries and keep them charged, and then use an inverter to provide long-term backup power; maybe that's what you meant.
I thnk you're right. The product I'm looking for doesn't exst yet. I would ideally like to have whole house power conditioning (pure sine wave if possible, modified sine if not) including voltage regulation (120V constant), with zero transfer time if cutover to batteries is required. I don't need it to run for hours; eventually I will have a generator which has about 8 seconds of cutover time. In the meantime, like you, I just need ten minutes or so to get everything shut down. I like the APC UPS funcitonality that shuts down the computers for you if the power outage is extended, in case an outage happens when I'm not at home.
The main problem seems to be that zero transfer time with current technology means you're running off batteries the whole time, with line voltage recharging the batteries constantly. That not only is expensive in terms of battery sizing, but it chews up batteries meaning high ongoing operating expense. From what I can see, the APC Back-UPS and Smart-UPS are good alternatives. Smart-UPS is more expensive, but has sightly shorter transfer times (4-8 ms versus 8-12 ms) and delivers pure sine wave power.
I was hoping that rather than buy UPS for 4-5 different locations, I could do something on a whole-house scale, which would benefit all the electronics. Thanks again for your input.