Inverters: Efficient, Reliable..Help!

Are you looking for 5KVA power inverters with around %90 efficiency, like the ones found by doing a search on GlobalSpec. Or are you looking for an online information source on making your own inverter hence re-inventing the wheel as your name suggests?

Thanks a lot guyz, i appreciate your contributions. howeva, beleive it or not, i dont exactly believe in reinventing the the wheel. I chose this task bcos i've actually seen people build these things (high powered Inverters). I mean electronic/power hobbyists. As a matter of fact around here, it is more expensive to importy them than to buy locally made ones (i.e. well built ones). Since i design smaller electronic devices myself, i felt it would be a worthwhile challenge. i dont know about cost but with the right materials - technical resource, i'll be suprised if i'm not succesful. especially when you add your help to the equation.

It really is a waste of time trying your chances of sucess are nill. Go out and bye what you need. These things can kill if you get it wrong. 5Kva 5000 watts is a lot of power, you need more than one, and a big stack of expensive batteries. This would need to be a 48V system to keep the conversion realistic not a home brew job.

I don't agree with the above numerical assessments, but I do agree with the first sentence. You chances of success are virtually nil, and a failure could be deadly to someone. You will also likely spend 10 times to build your own what it would cost to just buy one already made. You cannot possibly hope to compete with the economies of scale afforded to someone who makes 4 of these every hour. Your engineering time might be pro-bono, but the componentry to do it right and safely will cost an arm and a leg. then if you make even a small mistake, a fire is the likely result.

Go help them to buy one.

Thanks a lot guyz, i appreciate your contributions. howeva, beleive it or not, i dont exactly believe in reinventing the the wheel. I chose this task bcos i've actually seen people build these things (high powered Inverters). I mean electronic/power hobbyists. As a matter of fact around here, it is more expensive to importy them than to buy locally made ones (i.e. well built ones). Since i design smaller electronic devices myself, i felt it would be a worthwhile challenge. i dont know about cost but with the right materials - technical resource, i'll be suprised if i'm not succesful. especially when you add your help to the equation.

A deadline is going to be the biggest hurdle. A large inverter like this is not something that can be thrown together (especially with no power engineering experience). Learning the basics (and how to build something that is safe and reliable) will take time.

What's the application, expected load types and output voltage. What were you thinking of using as the input (12V batteries, etc). This should help narrow down the alternatives.

Thanks a lot Jack of all trades, for your message. Actually i'm not as handicapped in electronics as it may seem. I guess i can say i'm kind of conversant with the basics. My main concern is practical, specifics for about 3 computers and a deep freezer (regular office/ household appliance, no power tools, not more than 3 kva at a time). For input, a 12v, 200ah battery was my line of thought. Output voltage would be 240V. I believe the switching technique and transformer specs would be the most crucial factors?

So its a UPS (Uninterpretable Power Supply) you are really after for short-term backup in the event of loss of 240V supply. 5kVA is fairly high, requiring more than just a standard off-the-shelf design, especially with a 12V input (that's something in the order of 550A being pulled from the battery with a 90% efficient inverter). I know of no readily available designs that you could build that even approach 5kVA.

This project is actually far more complicated than it might first appear (even the battery charging and status monitoring circuitry is complex to implement correctly). The transformer would more than likely have to be custom designed and wound (and inverter transformer design is an art form of its own). I would have to suggest that you rethink the loads that you want to backup (a deep freezer can go a few hours without power, and I am sure you could live without the coffee maker in the event of a blackout), and look at purchasing a much smaller UPS. In the end there is nothing worse than an unreliable UPS that fails to work when you really need it (or catches fire and burns the building down).

Well i am already conversant with trickle chargers ( battery monitoring and charging circuits). i have designed working trickle chargers in the past and gell cell battries do not really require much maintenance ( with a good charger installed). So please what i really need to know, in the light of all i have gathered is: would building one (let's say 3KW) really be costlier than buying ( including shipping and all to west Africa from the states)? I may know a site that says it won't. thanks. What designs do you have? thank you mucho