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does an UPS is use like an instant power supply?

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mamun2a

New Member
does an UPS is use like an instant power supply?
i wish to operate a 40wt tube and a ceiling fan with an UPS, is it possible?
someone told me that an UPS generate square wave which is not operate a Ceiling fan, is it true?

if true how to convert a square wave to sine wave or is there any fan which is both for sine and square wave?
:eek:

BR
mamun2a, dhaka, BD
 

RCinFLA

Well-Known Member
Many UPS supplies are modified sinewave output. This is a three step squarewave, repeating zero volts, +155v, zero volts, zero volts, -155 v, zero volts. All these increments are about 1/6th of a full period of sine wave.

Modified squarewave would be a more appropriate name.

As to whether it will run what you want. Assuming UPS can handle the load, the fan will likely work but have a rather loud buzz. Also any speed controller will likely not work, being ON at any setting. The fan motor may run hot.
 

georgetwo

Member
i agree with RCinFLA the ups generates a modified sine wave

don't bother to connect it directly to your fan, the fan will work well but you will get a hmmmm sound from you fan when working. if a capacitor is added across the output (ac capacitor withe average capacitance) that will solve the problem
thanks
 

mamun2a

New Member
i agree with RCinFLA the ups generates a modified sine wave

don't bother to connect it directly to your fan, the fan will work well but you will get a hmmmm sound from you fan when working. if a capacitor is added across the output (ac capacitor withe average capacitance) that will solve the problem
thanks
are u sure, it works?
 

georgetwo

Member
my friend made an inverter which was connected to a fan and lcd tv, he had the same problem it was solved with a capacitor. i am sure it will work
 

RCinFLA

Well-Known Member
Putting a capacitor across output of modified sinewave inverter is not advisable.

It depends on what sized cap you are talking about but any cap that is going to 'round the edges' can cause high surge current through the output H-bridge MOSFET devices, potentially damaging them.

You might improve the hum with a filter at the fan. The filter is an L-C configuration. Should be selected to match the load of the fan.
 
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Noggin

Member
photographers sometimes use battery powered pure sine wave inverters. That may work for your needs.
 

mamun2a

New Member
last night i talk with a IPS/UPS producer, he told me that some UPS is semi sine wave, and 24 volt/2 batt ups can solve my prob, it is semi sine wave and serve 1fan 1energy bulb at lease 1 hour. if so then what is prob with CAR 12 V 50Amp batt, it serve me more, i told. he said it will be burn the ups circuit when the fully discharged batt is trying to charge again because the ups has only 800ma charger to charge 12 v 7AH batt. also warn me that car bat cant charged with the adaptor bcoz car bat is strong cell batt 4 30 second hi amp supplier, is there different type of batt for IPS and CAR?

i am confused
 
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tcmtech

Banned
Most Helpful Member
What I and a number of others have done with old UPS systems when the internal battery goes bad is rewire them with a set of heavy lug terminals on the back or top. That way they can be hooked up to a larger external battery source.

Most UPS systems internal charging circuits cant handle bigger batteries so well and its recommended to put in a separate internal battery charging system that fits in place of the old battery location. Have it charge the battery with a much higher peak current up to the float voltage of the battery and then shut off. The original charging system will then maintain the battery in the proper float condition without problems usually.

Also consider Most UPS units are designed for short term power output. They cant handle extended run times at their higher power rating when hooked up to larger battery's. Typically when run at their maximum rated power the internal battery goes dead about the same time the inverter overheats!

So when using an over sized battery system keep the power consumption lower. Typically half of the peak rating is all they can handle for extended periods.

Also car batteries dont make good UPS batteries. They are designed for high cranking amps but need to be recharged immediately afterwords for best performance and life. Use deep cycle or marine rated batteries for backup power. They are purposely built to handle the long discharge cycles far better than a car battery can.
 

georgetwo

Member
I dont know what hapens in the inverter when the capacitor is added but it seems to reduse the hmm sound and even the lines that may apear on lcd tv. the guy i told you used non electrolitic capacitor 222 (240v). he now uses the capacitor from a floricent starter. he could not tell me how it worked because he just tried and found that
 

mamun2a

New Member
i again come with the problem
what is the sol for use ups as ips
 

Nepalien

New Member
If I were you I wouldn't try to run fan from UPS simply because it is so inefficient. Consider using a DC fan that runs directly off a 12V battery.

I have improvised a UPS to act as a inverter using a external car battery. The UPS powers a computer and few CFL bulbs during power outage. The key is to get a good quality charger.

Here is the link of my blog:
http://bit.ly/dgYLy7
 

Reloadron

Well-Known Member
Most Helpful Member
Did anyone even bother to read what Hero linked to?

UPSs come with output waveforms in a variety of flavors. Everything from a square wave, to modified square wave, to a reasonably good sine wave closely duplicating mains power.

If you run an AC motor designed for a sine wave on a square wave or modified square wave you can expect it to hum loud and run hot and have a shorter life. AC motors like fan motors are cheap motors to begin with most of the time. I mean fans for personal comfort. They are designed to run on a sine wave and not what most low end UPS units produce.

Tcmtech also put out information regarding running a UPS off an automotive battery for extended run time. The suggestion is use a deep discharge battery. That will assure longer run time but not a higher power output from the UPS.

You want mains like power? Then you need a true sine wave output from a good higher end UPS inverter. There is no east way.

Ron
 

Hero999

Banned
Some single phase motors will burn out when powered from a modified sinewave.

Filtering and start capacitors can also fail because of the high harmonic currents.

I've run a fluorescent lamp with a magnetic ballast from a modified sinewave inverter and it made a horrible noise so I replaced the ballast with an electronic one and it was silent.
 

tvtech

Well-Known Member
Most Helpful Member
Did anyone even bother to read what Hero linked to?

UPSs come with output waveforms in a variety of flavors. Everything from a square wave, to modified square wave, to a reasonably good sine wave closely duplicating mains power.

If you run an AC motor designed for a sine wave on a square wave or modified square wave you can expect it to hum loud and run hot and have a shorter life. AC motors like fan motors are cheap motors to begin with most of the time. I mean fans for personal comfort. They are designed to run on a sine wave and not what most low end UPS units produce.

Tcmtech also put out information regarding running a UPS off an automotive battery for extended run time. The suggestion is use a deep discharge battery. That will assure longer run time but not a higher power output from the UPS.

You want mains like power? Then you need a true sine wave output from a good higher end UPS inverter. There is no east way.

Ron
Quoted For Truth.

I installed a UPS system on my families farm. They have NO mains electricity and rely purely on Solar Panels in the daytime and a Diesel generator at night.

A cheap normal UPS is fine for TV's and anything without windings. Transformers, Motors etc. all take a hit.

I suspected something when my Sister complained about mains Fans that stopped starting and radios with transformers that melted.

Now my doubts have been confirmed.

Heck, I really enjoy this Forum. Never too old to learn.

Jeeperz.....cool place to hang out. And help and learn at the same time.
 
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