Non-Sinisoidal Power Supply

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Is there a specific reason that you have to ask only kinder-garden questions in an engineering forum? If you are just strictly following your "motto", please don't take it too seriously because if you ask me, a wall made of bricks called failures is sadly called a wall of failure. It is not called success.

Sweet! I needed a wall of failure that I could hang my many certificates of shame on!

Life is good!

Um.... No.... Wait? Hmmm..

Well said.

And here's something for the OP (assuming it's a person and not an AI trying to build itself):

You can print it out and post it on your office/cubicle wall.

Is there any 'specific' reason you double posted? Read the forum rules!

Failures don't read the rules.

Or search for answers before asking ridiculous questions.

Or spell sinusoidal correctly.

Thank you, Lyn. You have a great way of telling people what they should already know, in a way that makes me smile.

Know that it is a sincere complement when I say you are one of my favorite curmudgeons.

Most of us go out of our way to help those who deserve help and give some indication that they at least some common sense.

I have no patience with those who are too lazy to do any of the work themselves and are habitually helpless, OP being a prefect example.

Cheers.

Well he's a high functioning simpleton who is a "2nd year b.tech in ece".

He only has 10 more years to go on that education.

Well I went back to school a second time for a EE degree years ago I can easily see where a simpleton could be at his parent educational level or higher and have no clue about his own field.

It's not hard. Most any 5rd graders from 20+ years ago could hack at least a basic bachelors degree today.

Heck most anyone who graduated pubic school with a 3.0 GPA or higher 40 years ago would likely have qualified for high level multi doctorate degree by todays higher ed standards.

Hey now if it wasn't for failure some people would never have anything worth noting in their life to claim as their own.

(IS there any specific reason of not using these type of ac power to our home appliances ) .

#1 Read the features of each one (sin/square /ramp/....) wave .

#2 read about the sources(generators/converter.Systems) of each one.

#3 read about loads behaviour under each supply source of those waves

there is no short answer.as your question above.

Rixter gave you already the reason seen from a generation standpoint. Rotating machines for generation generate sinuses in general. You can find it when you project the vector of voltage and/or current over a time axis.

Some grids show saturation where the tips are flattened. This can lead to extra losses in the transmission lines, the transformers and may contribute to excessive heat.

Non resistive loads change in value since impedance in coils slide more towards the elementary DC resistance value. A square is in fact a "clipped" sinus with a threshold.

Why?

And who says we cant use it?

Correct todays live is already filled with DC. Think of laptops, computer, mobile phones even light applications. Most is in conjunction with batteries.

We generate square waves from solar systems but the reason why we have sinusoidal wave form is that we generate it with a rotating generator most of the time. OP question does not take that into account or the question would have been different.

So there is applications for square wave forms, but this was not the question.

The way I read OP is why we do not change our power transmission system over to square waves. So what is your answer to that?

The OP asked about powering home appliances.

To me, in my limited knowledge, the means generally motors.

You fail to mention motor heating, noise, or power supply complexity as reasons not to use square wave power and why the as-supplied AC sine wave power is used.

Point is that Lokeshloki comes to the well without even cursory knowledge of the subject to hand and expects an immediate infusion of knowledge from those who have spent years developing the knowledge he so selfishly expects the forum to provide to him, instantly.

No one here will care if you provide him with the benefit of your considerable knowledge.

Eventually, the mosquito buzzing around looking after a free meal deserves a swat.

I believe in expanding people's horizon's with answers that give them more options than what they started with.

I don't believe in repeating the simple answers that they can find in any textbook.

The OP's question may have a very limited scope but is it because he is lazy or is he just beginning to explore our field?

Anyway, have a good time insulting new comers. Good bye for another few years...

Don't go away. You can help always ignore my comments and provide answers to the unknowing.

Running away on your part will not help making this forum better. What do you expect to have changed in a couple of years?

When the old are gone there will be new ones growing weary. You can make the change. Stay and make it better. OP should come back to you to get more help. At least stay around for that.

How does your belief in supplying answers to expand people's horizons get along with your planned absence and resulting unavailability to provide such answers.

Is nonparticipation really a horizon expanding answer?

...and what about Lyn's horizons? Doesn't he also belong to the category, people?

Hang out with my wife and daughter for a week (especially my wife on a bad week) or two and answer questions over and over that a literal seconds worth of rational thought for most people would have answered and see how your general disposition towards the blindingly oblivious asking the blindingly obvious starts to sit with you.

Please don't leave, without you, the helpful person to bully ratio will skew even more to the bullies.

That's how good neighborhoods with a small bad element become bad neighborhoods, then worse neighborhoods. The good people leave, and then there are just the bad people left, which scares away any good people who want to make an improvement.

If you want this forum to get better, stay and HELP it to get better. Leaving only means that the trolls get to win.

A happy Easter too and A GA from a member of the frustrated senior committee.

You don't feel the cynic frustration of a bunch of ol' men.

The GA is for part one on top of the line.

Under the line you give us a look in a trick box, or how inverters and converters feed the motors to make these do some more smart moves as they cannot perform from their original design.

You are right, that you can call it also a power supply. (a kind of drug like steroids, for motors perhaps)

Step, accelerate, brake. To name the simplest.

When it is not too hot, I also experience some heavy equipment (one drag line with a scoop as big as a truck load) take down one part of the sinus since the power company isn't able to compensate for electronic speed controls that are used in that part of the sinus. Lots of these wonders (the heavy ones) are dirty and dangerous grid contaminators.

There's actually a few valid engineering reasons why a sinewave is preferred. Basically it's relatively smooth with no sharp discontinuities as is found at the peaks of a triangular wave, or the really rapid change in polarity of the zero crossing of a square wave.

Those discontinuities cause harmonics, noise (mechanical and electrical depending upon the device), and excessive/unexpected currents especially from the triplens frequencies which are additive. The problem is particularly severe for square waves which when applied to inductive circuit elements, cause very large spikes that can damage/puncture insulation.

That is not to say that they can't be used (UPS, VFD, VSD, SMPS, Inverters, basically any nonlinear device, etc. do all the time), it's just that the device/circuitry is/should be designed to deal with the effects of the waveform presented by/to it. Choose your waveform wisely and make sure the equipment is engineered to accept it without failing.

Yes existing appliances would either not work or would be destroyed.

Motors naturally produce nice sine waves and transformers hate sharp or square waveforms, since these two devices are integral for our power generation and transmission grid it made sense to stick with sine waves.

Try researching the history of alternating current generation and transmission for more information.

You could ask the same question for the 50/60Hz issue between EU and US

or 120 and 240V

In Japan they tend to mix it over the islands, so they can't be connected by simple underseas cables.

Why the difference and why isn't anybody working on changing it?

It's grown historically and for each system there are pro's and contras.

DC versus AC is basically a marketing story, as even in the old day's DC was as easy to handle in big distribution systems as AC (DC has way less distribution losses and requires only one cable) but somehow it is assumed that DC is more lethal than AC.

Read the code on low voltage and you will conclude differently (DC is assumed to be safe up to 75V where AC is limited to 50V RMS)

Back in the day's of Nicola Tesla a sine wave was very easily made from a rotation and an asynchronous cage motor was a very sturdy piece of equipment that was very reliable. It required little to no maintenance. So the 3f AC system became an industry standard without any discussion. Who bothered on the efficiency of distribution at that time?

Moving away from a pure sinus would pose serious issues as mathematically this means adding harmonics.

The attenuation of a signal is a function of it's frequency (higher frequencies will reduce faster down the line)

Add these two and you will have a signal that will change shape deeper in the network. Only a pure single sine will survive till the end, or a pure DC signal.

Loads of reasons. You ought not to invest in anything that anyone is peddling that does otherwise.

The power (electricity) is transmitted in the form of sine wave, since it is more advantageous then other waveforms, so sinusoidal has been made choice to choose. However u have questioned a very nice one, keep posting this type of posts

The best way to not bang the innocent newcomers is to keep quiet and do not reply. That much wisdom misses in many here. Everytime answering search the net is only a means of increasing one's number of posts.

A person can simly become great if he apologizes on making a mistake.

I invite you to make this post off topic, go ahead.

Gajanan Phadte

If silence is the best response to avoid 'banging the innocent new comer', the newcomer is not really that innocent.

.

'That much wisdom misses from many in here'.....

....hmmm, so the wise path would have been to leave no comments....except it is tough to let everyone know how wisely silent you are being without speaking up.

.

Anyway, for any particular comment, there are so many things that didn't make the cut....that seems like a lot of wisdom that you missed?

Probably a good idea to have a quick look at previous questions and comments by Lokeshloki as it may explain the views of a few of us on CR4 that may not be clear.

My comments summed up what others were thinking at the time (and yes myself and others tried less confrontational methods numerous times before it came to this).

http://cr4.globalspec.com/thread/99996#comment1080314

Sometimes you have to use the big stick to make them listen to your point so they can learn from their mistakes and come out better in the end (the whole point of CR4 after all - personal improvement in career and life).

'... Is there any specific reason of not using these type of ac power to our home appliances?...'

.

There are numerous specific reasons. The most significant specific reason square wave hasn't powered your home appliances is.....

Inductance.

Even if you got around all problems noted in other replies and a square wave power supply were attached to the homes wiring, inductance in the system would mean the appliances would not be powered by a square wave. Rather, the appliances would receive a complex waveform that could be approximated by combining numerous sine waves.

.

So, not only is it not a good idea, it isn't feasible.

Everybody has positives and negatives. I wouldn't say that I listen to everything others want me to, nobody does.

Once, a mother brought a child to Mahatma Gandhi complaining that he eats sugar and she wanted Gandhi to convince him against doing it. Gandhi told her 'come tomorrow'

Why...Gandhi himself stopped eating sugar that day so that he could advice others.

World is a nice place because of all the good things and also the bad. Otherwise how would you appreciate good.

In my opinion, the people who say he is wrong judge the creator. After all he is HIS creation.

Nobody knows everything even of his profession and subject. Knowledge level differs. The Gurus also can leave such replies to the less knowledgeable. After all, a kid can ask any question that the most educated cannot reply.

Also, the net contains answers to almost everything.

Nothing personal...

Gajanan Phadte