May TV powerd by Square Wave UPS

How old is the TV? Many newer ones actually rectify the incoming power to about 12VDC. If yours does this it won't care if it's a square wave.

Beware however of RMS values that now no longer apply due to the square wave. You're going to get the full monty in terms of input voltage.

Hello guest,

Electronic Engineering - is a discipline dealing with the behavior and effect of electron and with electronic devices, system, or equipment.

Electronic Engineer - develops, design, assembles and test electronic system, component and equipment.

Opppsss, sorry i include to put definition on your first sentence "electronic engineer".

On my understanding correct me if i'm wrong, The UPS inverter only switches on (with a small break in supply) the main fails or fluctuates widely outside the input voltage window of the built in automatic voltage stabilizer.

The three basic wave form type use with ups are Square wave, sine wave and quasi-sine wave. the cheapest or low cost one was the square wave that is why maybe you selected to buy and the quasi - sine wave is the next one then followed by sine wave. sorry i'm not an Engineer same as you but on my experience the cheapest one will give you less efficiency but will work, but not as good quality as the expensive one.consider the brand of the unit as well.

Kind regards

Roman

I would go further than the others and say NO it won't work and may well damage your TV.

The reason is that the input will be a full wave rectifier to a switch mode power supply. This input will be filtered to stop spikes and noise from coming into or leaving the power supply.

The filter network is designed to cope with harmonics of a sinewave but not the very large harmonics found on a square wave, and so the filter components will be overloaded, i.e. the input capacitors etc...

Further, as the first post said the relative crest factor difference will make the square wave when rectified and filtered much higher a voltage than a sine wave supply. As you are using 220 volts which is nearly at the top of the input voltage range, the additional voltage may well take out the smoothing capacitor by exceeding its rating. Both in voltage and in transient current ratings.

Then we come on to the effect on the TV circuits of the massive radiation of the harmonic component of the incoming power...

Square wave may be okay for motors and lamps etc.... but not for electrically sensitive instruments.

In case your TV works with a switching power supply the square wave is okay. If it starts with a transformer the peaks on the low voltage side can be too high.

I wouldn't want to say whether yours would be hurt or not, I had occasion during a recent power failure to hook up my 500 W inverter to my 27 inch JVC. Unfortunately it did not have sufficient capacity to handle the the current surge on starting. For one reason I ended up with a purple section about 3 inches square on the top right hand corner of my screen. Obviously the screen needed to be degussed, fortunately it did it itself after a few restarts on commercial power.

I doubt this will be of any help to you, unless my screen problems were caused by the square wave from the inverter, instead of a phenomenon associated with my inverter overloading.If it is caused by the square wave , take heart and don't empty the Maalox bottle, it can fix itself.

Hi all,

You can run the TV on your square wave inverter. You may find, if it is an older unit with a transformer that the power supply may be audibly noisy. Some equipment will not run properly on square wave due to the low peak voltage. I am speaking from a lot of experience as my home runs on a PWM inverter and it is also my business. (Square wave 230V has a peak of 230V while sine has 325V peak.)

Does your inverter really have a square wave output? Most units nowadays have a pulse width modulated output with a peak of about 320V. The peak voltage directly relates to the battery voltage and as that drops with discharge the width of the pulse increases to maintain 230V rms. the limit to this is generally when the pulses are so wide that the waveform becomes a square.

regards

Chas

Hi everyone.

Thank you for all replies to my email;

Thank you Chas, i think you can help better as you relates with this field.

The TV is not very old modle but please will you told me that as the sqaure wave is distorted on peak as compared to sine wave, and sine wave is better one due to the wave shap, than what harms may possible due to square wave supply, however the supply is stablised to 220 to 230 but not increased than this.

Will the square wave effect the colours of TV after some or long time use of UPS.

I am using 1500VA UPS on 25" TV.

How we can find that a UPS is good or bad for such an application.

No problem. you can use this inverter to your tv and other applances.

neednt so large power, only 200va enough.

no matter your tv is powered by online or offline power supply.

both sine and square wave can work well for tv. no problem.

but if your inverter is not good quality, it will produce some interference signal.(radio interrupt) then you can add a low pass filter.

you may come form india. electronic engineer means semiconductor engineer in your country?

Thank you for yor repy

I am from Pakistan,and yes we our country electronic engineer is semiconducter engineer.

How we can came to know that a UPS is good or bad, because newly all work good but after some time appears problem of different type.

bestregards

Hassa Sardar Khan

A true sine-wave output UPS would be the best in all cases, but these are quite a bit more expensive than the "modified square-wave" ones. If you want to be sure your UPS will work with all line-powered equipment, go with one that has a true sine-wave output, if you can afford it.

Tom

Hi Sardar,

Both CN and tdesmit are correct but since you presumably already have your inverter you have to use it until your budget allows replacement.

Something you should be aware of is that both square and "modified sine" (Pulse output) units have high freq components in the wave and some domestic equipment will fail with this. The type of equipment that is prone to failure are things like the power circuit for the programmer on washing machines, microwaves, dishwashers etc. These power supplies are often no more than a capacitor, resistor and a zener. Most of the voltage is dropped across the capacitor and so when the higher frequencies of the non sine wave are present then the diode and resistor have to dissipate more heat and they burn out. The problem with this is that you cannot know without investigating inside the machine whether it has this type of cheap power supply circuit or not. Your TV will not be like this and will be OK

Regards

Chas

Since you are an electronics engineer you should better reply this question. Or are you trying to check our capabilities.

If you don't know the answer of the question stop calling yourself an electronics engineer.

Hi Rakesh semwal,

You are very rigth, if you noticed my comments above which is rated 2 as off topic. that is the simple message that i am pointing out. why you have to introduce yourself as electrical engineer then your question is "how can i convert ac to dc" or "what is the kW of 250 amps for 400 volts"? then later on found to be not a guest but a member since October 2008.

In addition to the above comments, I would caution that if the power supply in the TV has power factor correction, it may not play well with a square wave input. You may wish to find out what the DC link voltage is in the power supply and supply that directly using a DC-DC converter.

Just curious. Why connect TV set to an UPS to begin with?

No one? Maybe the OP was with respect to CCTV? Can't think of any other reason.

Perhaps he doesnt want to miss his favorite soap opera!

But more seriously many parts of the world the supply is really unreliable

Good point about the grid (or otherwise) reliability thing; maybe UPS would help if line outages and anomalies were consistently very-short-lived. However, if it's outages that persist the UPS could simply be a kind of "wish and a promise" way of prolonging the agony...if you get my drift. OP didn't say if analog or DTV...but I 'spect the former isn't going to go very long on the described UPS. Anyway...to each his own.

Depends on the battery size. if it's external battery it could be any size.

I must admit that I mis-read the OP as inverter rather thn UPS but he gives no capacity to the kit he has.