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Need pure sine wave input for UPS

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Last response: in Other Consumer Electronics
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April 1, 2011 9:44:46 AM

Hello,

I am in the military and stationed overseas on on-base housing. Our wall sockets are 110v 60hz. However, this is after running through a large transformer that intakes commercial 220v and outputs 110v to the house. I have an UPS that goes straight to battery power when plugged into an outlet. It recognizes a stable input voltage of 113-115v but will not accept it to charge the battery. After some troubleshooting with APC we identified the problem is the transformer which apparently does not output a pure sine wave which the unit requires.

So my question is: Is there some sort of ac/ac line conditioning device that will output a pure sine wave? When I look for pure sine wave devices all I can find are dc/ac power inverters. It seems like this should be a pretty simple item to find but it doesn't seem like they exist.
April 1, 2011 7:57:33 PM

> So my question is: Is there some sort of ac/ac line conditioning device that will
> output a pure sine wave?

Because electronics are so robust, then no such power source is required. However, a pure sine wave means maybe $1000.

A UPS is often made as cheap as possible. If a power source has anomalies, a cheap controller can become confused. That UPS will stay in battery backup mode.

Anomalies would be not created by a transformer. May be from something also connected to that transformer. Or maybe from something sugggested below.

Forget a line conditioner. You are asking for what is better called a series mode filter. Brand names associated with these more serious filters include Surgex, Zerosurge, and Brickwall. Some will foolishly recommend these as surge protectors. Sales can be increased by selling on subjective claims. These filters are completely different from surge protectors.

That assumes your problem is a noisey waveform. I see nothing that says voltage is noisey. Just as likely is a low voltage. 110 volts actually at 100 volts (which would be a normal voltage) is more than sufficient to power all electronics. But may cause some UPSes to remain in battery backup mode. Without numbers, nobody knows what is causing failures. To know more means measuring voltages with a multimeter.
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April 3, 2011 6:47:03 PM

Thank you for your reply. As it so happens my job is satellite communications, so I have access to a multimeter. I'll borrow one from work and take a reading. Is there anything else I need to know besides exact voltage?
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April 3, 2011 7:19:28 PM

submatrix said:
Thank you for your reply. As it so happens my job is satellite communications, so I have access to a multimeter. I'll borrow one from work and take a reading. Is there anything else I need to know besides exact voltage?

You would have acces to an oscilloscope and know how to use it. More potentially useful information may come from viewing AC waveforms. Maybe identify other appliances that create (sources of) AC line anomalies.

Japan typically has a lower 120 VAC standard. Whereas US domestic AC can drop from 120 to 110 and be acceptable. Japan's 110 VAC can drop to 100 volts and also be acceptable. But that might confuse a UPS designed for the slightly higher US domestic voltages. A meter on 200 VAC settings will say more.

You should also have access to a variac. Simply connect that UPS to a lab variac. Lower AC voltage. Learn at what point the UPS trips out to batteries. And at what point a rising voltage finally clicks its relay back to a direct AC mains connection.

Some additional ideas to consider.

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April 10, 2011 9:03:54 AM

I hooked up the o-scope and the sine wave looks pretty solid, but then I noticed what is probably the real problem. The waveform is only 50hz, not 60hz. I contacted base housing and he confessed he didn't really know, he just assumed that after it went through the transformer it was 100% US spec. Though transformers don't change the frequency, just the voltage. And since the UPS requires 60hz input, that's probably why it is failing.

So now for a new question, is there any device that can change the frequency from 50hz to 60hz? Some people at work suggested going through an ac-dc converter and then back through a dc-ac inverter. However, to be able to handle the watts that the UPS will pull could cause it to be cost ineffective. So followup question, if there isn't a device that change the frequency, do they makes UPSs that opperate on 120v 50hz?

Thanks again for your help.
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April 10, 2011 3:53:55 PM

submatrix said:
So followup question, if there isn't a device that change the frequency, do they makes UPSs that opperate on 120v 50hz?

For a $100 UPS, spend many $thousands to convert 50 Hz to 60 Hz? Get a UPS designed for 50 Hz and for that slightly lower Japanese voltage. It already does AC-RF, RF-DC, and DC-AC conversions. APC will have a similar UPS with only a different option number for that slightly lower voltage and 50 Hz.

Or address why you need a UPS. Its only function is to provide temporary and dirty power during a blackout. What is that UPS to solve?

Meanwhile, the reason we fix things is to learn. You have a perfect example of why engineers ask questions of others that make others angry. Because those others too often only 'assume' as base housing did. His job was to know these numbers. Learn from the experience. Appreciate why technical people must ask questions repeatedly that literally make others angry. People too often assume so as to ignore numbers. Many also have a UPS that does not do things they have only assumed it does. It does one thing. Provided temporary power during a blackout. How often are your 5 second or 10 minute blackouts?
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April 10, 2011 5:21:59 PM

Thank you for your response again. We are stationed in the UK and the "Queen's Power" as they call it is unreliable where we're at. We lose power probably 2-4 times a month. When we lose commercial power, the base switches over to base power, but this requires another break in power (typically the same day) to switch back to commercial power. So power outages typically happen in pairs. So I mainly just want the UPS so I have time to save whatever I'm working on and shut down.
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