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plz help me: inveter design

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I know what your saying! Most of the people I work with would just run the 125 kw and say its justified in case they might need to run something big someday before the project was over!
Or they would say, Well the litle ones would work but I will have to change oil on them every few days, but the big one can run all month without an oil change and when it needs it I just have to make a phone call and a service guy will come out and do it for me for $100.

And sorry we cant pay you for the work you have done for us. The company has no money right now. Our opperating costs have ate everything up.
 
And sorry we cant pay you for the work you have done for us. The company has no money right now. Our opperating costs have ate everything up.
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I've heard that one more then once
 
I don't have a windmill. I also don't have a solar panel array and big batteries with an inverter.
But my electical consumption is half of my neighbour's.
Our meters were changed and reset at exactly the same time.
My neighbour lives alone and wastes as much electricity as she can.
My wife and I (and frequently my mother-in-law) save as much electricity as we can.
 
My wife and I (and frequently my mother-in-law) save as much electricity as we can.
I no that feeling save as much as you can they raised or power bill 35%
 
My neighbour lives alone and wastes as much electricity as she can.
My wife and I save as much electricity as we can.

You and your neighbor sound just like me and my brother. :D

I do use a lot of power per month but by far the shop equipmnet is responsible for it. I put an independent watt meter in when I wired it some years ago. A good day of plasma cutting or welding can easily run up over 100 KWh. The house itself only counts for about 25% of my total monthly usage.
I do have my little wind generator and its GTI unit. So far that runs about 30-40 KWh cogenerated per month. Its Small but it is helping! :)

I hope to get the big one done this summer so I can do 100% of my average monthly useage. Or at least half would still be nice.

My brother on the other hand leaves everything on. I can go over there any time and the garage lights are on, The TV is always on, most of the lights in the house are on, the flood lights on the house and garage are on more than they are off, and no one is home! :eek:

I have gone over there to borrow stuff while he has been on work related trips for a week and every thing is still on! :eek:

He says most of that stuff doesnt use that much power.
According to him its his main computer and server that take all the power! (I think I have heard that some where else too) :confused:
 
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Hi,


Just a couple of notes on the 'inverter' previously linked to in this thread...

First, the LM324 isnt a great driver for transistors. If anything, the output of
the CMOS would be better as the rise amd fall times will be better.

Second, and probably even more important, there is no 'dead time' built into
the inverter. The dead time is the time delay between the switching of opposite
transistor groups and works out as a time delay to turn on and no time delay
to turn off the transistors.
What happens is the transistors on one side turn on and when the drive signal
tries to turn them off they dont actually turn off for some 10us or more. During
this time if the opposite bank turns on it will cause a very low impedance short
from V+ to ground through the output transformer even though the collectors
go to opposite sides of the transformer. This will cause a huge surge which is
considered very destructive and usually blows the transistors.
By delaying the turn on only and not the turn off, the transistors that are
turning off get a chance to turn off fully before the opposite bank is turned on,
thus eliminating the near direct short.
The actual delay time depends on how fast your particular driver can turn off
the transistors and should be slightly longer than that. For fairly fast transistors
5us is enough, but 10us is better and due to the poor drive method used for
this inverter maybe 20us would be even better.

Just some things to think about before turning this 'inverter' on.
 
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really thanks guys for replying.... i think you have improved many miss understood points for me....

ya, i meant local inverter grid as be80be said... so i think i don't have problems with the utility grid because itsn't my aim... but i read that if the fed load is an inductive load the output from the circuit (square wave) is a problem, so i still have a problem with that output.... so if i designed the inverter based on the pwm of a microcontroller; does this solve the problem?!!!

another question.... for an inverter to be able to output higher wattage; does it depend on the input wattage and the switching transistor if they can pass a higher current through it or not only... or there is other factors?!!!

finally a request.... audioguru can you upload your fixed inverter schematic...

thanks for everyone i took from him a time to post a reply to help me!
 
really thanks guys for replying.... i think you have improved many miss understood points for me....

ya, i meant local inverter grid as be80be said... so i think i don't have problems with the utility grid because itsn't my aim... but i read that if the fed load is an inductive load the output from the circuit (square wave) is a problem, so i still have a problem with that output.... so if i designed the inverter based on the pwm of a microcontroller; does this solve the problem?!!!

another question.... for an inverter to be able to output higher wattage; does it depend on the input wattage and the switching transistor if they can pass a higher current through it or not only... or there is other factors?!!!

finally a request.... audioguru can you upload your fixed inverter schematic...

thanks for everyone i took from him a time to post a reply to help me!

1) Transistors don't make a very efficient Switching Device.
Mosfets are better.

2) You Can't get More Power Out than What you put in!
12 Volts @ 40 Amps is 480 Watts.
But Even an Efficient inverter is only about 90%, So your output will be only 430 Watts or LESS.

Here is a Fairly good Inverter using Mosfets. (Square Wave.)
**broken link removed**
 
The very old inverter circuit that I fixed uses old 2N3055 transistors instead of Mosfets because power Mosfets were not available in The Philippines where it was first needed. They used it to power fluorescent tube lights, incandescent lights and TVs that have an 80VAC to 250VAC power supply.

Many electronic products do not work properly with a square-wave because its peak voltage is much lower than the sine-wave from mains electricity.

These simple square-wave inverters use a huge, heavy and expensive transformer.
A modern pure sine-wave inverter uses one or two small, lightweight and inexpensive transformers with a ferrite core because they operate with Pulse-Width-Modulation at a high frequency. The modern inverters have voltage regulation and shut off when the battery voltage gets low.
 
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