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audioguru
Nobel Prize Winner
Canada
4218 Posts |
 Posted - Jan 22 2008 : 10:09:06 AM
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I have never made a power transformer. I just buy one when I need one.
The voltage stepup of a transformer is determined by the ratio of the turns on the secondary divided by the number of turns on the primary. If it is center-tapped then the ratio is doubled. If there are not enough turns on the primary then the current will be high without a load.
Look at the max current rating of various sizes of wire. The wire's heat is concentrated in a transformer so thicker wire will be cooler. |
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mira
Apprentice
57 Posts |
Posted - Jan 22 2008 : 10:11:54 AM
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| Thanks again. I will follow your advice. |
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kako
New Member
4 Posts |
Posted - Jan 26 2008 : 10:29:38 PM
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Hey guys!!!
i just bought a 1500watts power inverter with 3000watts peak to try and use my air conditioner from a car battery. I dont know if i calculated wrong but my air conditioner uses less than 1200 watts and is a 120v 10amps or less. I tried using a 750 amps car battery but when i turn the air conditioner's compressor on; the power inverter turns off and starts beeping.The powert inverter haves its own power metter and when the compressor turns on it doesnt even get to 1000watts. I bought this power inverter on ebay, does this means that the power inverter isnt truly whats it says it is or am i missing something???? Is there any way for me to remove this safety switch to force the inverter to work under this conditions without shuting itself down??? i really dont care how mush time can the battery move the compressor but i really need to turn it on.
Please if you guys think of something help me out here |
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Jan 27 2008 : 02:59:50 AM
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Maybe the inverter has a good specification but your car battery doesn't. 750A is "cold cranking Amps" when the battery is very overloaded which drops its voltage to 7.2V. It can supply only about 75A at 12V for maybe 3/4 of an hour. 75A at 12V is only 900W.
Your air conditioner might have a starting power surge much higher than its 1200W running power. |
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kako
New Member
4 Posts |
Posted - Jan 27 2008 : 6:00:32 PM
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| what type of battery you think would be best to use for this type of work??? |
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Jan 27 2008 : 7:23:25 PM
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I have never needed to use an inverter. I don't go camping and my electricity is very reliable.
To supply the high current to the inverter when it must supply a power surge to a starting air conditioner needs a pretty powerful battery. |
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kako
New Member
4 Posts |
Posted - Jan 29 2008 : 12:38:00 AM
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| I am really confused why would someone make a power inverter that goes up to 5000watts if you need the input power to be same as the output power. Is it even possible to find a battery with such Power like 1500watts that is not cranking power like car batteries??? |
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Jan 29 2008 : 2:34:08 PM
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A 5000W inverter gets hot. Extra input power is needed. Maybe it needs an input of 6000W from a battery.
An inverter with this much power probably uses a 48V battery to reduce its current.
There are some pretty big batteries that power electric fork-lift trucks. |
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kako
New Member
4 Posts |
Posted - Feb 02 2008 : 6:19:58 PM
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| but its input voltage is 12V so that would mean i would need a battery with constant 150amps maybe?? Does that even exist cause i know car batteries have more amps but they are cranking not coinstant |
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Feb 02 2008 : 6:55:54 PM
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150A at 12V is 1800W. A good inverter circuit could have an output of 1500W plus 300W of heat.
A car battery is used for only a few seconds so it doesn't boil when starting a car. It is not designed for continuous high current nor for deep discharge like an inverter's battery needs to be.
Huge batteries used in electric fork lift trucks can continuously supply high current without overheating. |
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troyboy76127
New Member
USA
1 Posts |
Posted - Feb 06 2008 : 9:27:53 PM
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| does anyone know how to change the frequency output on the inverter? i am guessing caps of different frequency. i want to be able to adjust it like a variable freq drive from 0-300hz....thanks..........troy |
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Feb 06 2008 : 11:39:14 PM
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Every inverter has an oscillator. One or two resistors and/or capacitors could have their values changed to change the frequency.
But first you must select an inverter circuit that works. The inverter here does not work.
When you use a transformer designed for 50Hz or 60Hz and try to increase the frequency then the transformer might not work well.
When you decrease the frequency then the transformer will saturate which increases the current and blows up the transistors. |
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Tolexp
New Member
Nigeria
1 Posts |
Posted - Feb 07 2008 : 03:30:52 AM
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| Good day sir,i got your inverter circuit diagram of 12v to 120v. i try to practicalise it, but am unable to get 68uf,25v tantalum capacitor in my environment.please sir help with a substitution for the 68uf,25v tantalum capacitor or any capacitor to reply, because i can't get it in my environment. thanks sir |
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Rifat Ahmed Khan
New Member
Bangladesh
1 Posts |
Posted - Feb 07 2008 : 05:10:56 AM
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Hello to Mr. moderator, Mr. audioguru and everyone reading this.
i'm a new member and having some difficulties. i visiteded some pages on topic_id=2996 on inverters but couldn't find any specific location for the design and schematics of an inverter. i am an U.G. student and want to work out a project on a transformerless 12v dc-240v ac boost inverter. probably this could be done using IGBTs. this is an emergency because i have to submit a project proposal by next sun day, 10 Feb, so, i need a material with complete theoretical solution and schematics. reading you i found that you are the best. Please help me. |
shuvo |
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pebe
Nobel Prize Winner
United Kingdom
1078 Posts |
Posted - Feb 07 2008 : 08:41:41 AM
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quote:
Originally posted by Rifat Ahmed Khan
.....i am an U.G. student and want to work out a project .... so, i need a material with complete theoretical solution and schematics.
Why do you expect someone else to give you a complete design for your classwork? |
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12/120V inverter again
