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Thread: Fried Inverter due to reversing polarity???

  1. #1
    Low Bitrate wonderworm's Avatar
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    Fried Inverter due to reversing polarity???

    Anyone know how important the polarity thing is on AC outlets? I've always gotten confused how to tell which way to plug in power cords for TV's, Radios, Computers, etc to make sure the positive and negative are in the right location and not reversed. Sometimes one slot will be a little longer than the other, but other times it is hard to tell.
    Honestly, I think you can plug in all the above products and not have an issue even if you plug it in backwards. Many times it's impossible to tell unless you have a third grounding plug to be sure it's correct.

    Well, I have 2 power inverters, a 300 watt and a 400watt. I had my carputer plugged into it as well as the ac adaptor for the LCD monitor. The monitor had no ground wire and I could only plug it in one direction due to physical limitations. However, I'm thinking now that the monitor AC adaptor was plugged into the Inverter in reverse and now I get the "Fault" light when I try to plug anything into the inverter. By plugging in the AC adaptor in reverse, I'm worried I ruined the Inverter.

    Anyone know if I fried the inverter permanently? The fuses in the inverter are not blown, I thought they would blow first if I hooked it up wrong but maybe not. I also opened up the 400watt inverter and couldn't see or smell anything out of the ordinary. Unfortunately, I don't have a voltometer.
    Any EE's out there to help me out?

  2. #2
    Low Bitrate frenchnew's Avatar
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    If it's a 2 prongs plug it should not matter unless your are plugging something that is not "Isolated" (Meaning that there is no transformer in it's power supply) and then you add another thing to the inverter outlet and somehow connect those 2 apparatus together.

    Example: You have a portable TV that is only built to work on household current. You plug this hing up to the inverter. You connect your car computer power supply (House computer supply) to your inverter. You then use the TV-OUT from your computer to the TV - You have a 50% chance of blowing something up as TV chassis are not usually isolated from the main current as it cost to much for the manufacturer to use a power transformer in the power supply.

    Depending on your inverter, unplug everything at its outlet. Get a household lamp and connect it in the inverter to test, is it working?

    Best of luck to you

    frenchnew


    Quote Originally Posted by wonderworm
    Anyone know how important the polarity thing is on AC outlets? I've always gotten confused how to tell which way to plug in power cords for TV's, Radios, Computers, etc to make sure the positive and negative are in the right location and not reversed. Sometimes one slot will be a little longer than the other, but other times it is hard to tell.
    Honestly, I think you can plug in all the above products and not have an issue even if you plug it in backwards. Many times it's impossible to tell unless you have a third grounding plug to be sure it's correct.

    Well, I have 2 power inverters, a 300 watt and a 400watt. I had my carputer plugged into it as well as the ac adaptor for the LCD monitor. The monitor had no ground wire and I could only plug it in one direction due to physical limitations. However, I'm thinking now that the monitor AC adaptor was plugged into the Inverter in reverse and now I get the "Fault" light when I try to plug anything into the inverter. By plugging in the AC adaptor in reverse, I'm worried I ruined the Inverter.

    Anyone know if I fried the inverter permanently? The fuses in the inverter are not blown, I thought they would blow first if I hooked it up wrong but maybe not. I also opened up the 400watt inverter and couldn't see or smell anything out of the ordinary. Unfortunately, I don't have a voltometer.
    Any EE's out there to help me out?

  3. #3
    Low Bitrate wonderworm's Avatar
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    Quote Originally Posted by frenchnew
    If it's a 2 prongs plug it should not matter unless your are plugging something that is not "Isolated" (Meaning that there is no transformer in it's power supply) and then you add another thing to the inverter outlet and somehow connect those 2 apparatus together.
    Actually, thats kind of what I did.
    The inverter has 2 ac outlets. I plugged the PC into the first, then I plugged the fat AC adaptor into the second which led to the LCD screen. Then, I have the monitor output going from the PC to the LCD screen. So these 2 devices ARE connected via the monitor cable.

    I also found some print on my other blown Inverter that says, "reverse polarity will damage unit". I didn't find anything like that on my 400 watt inverter but I think somehow that is what fried something in the unit.

    Hopefully others can learn from my mistakes.

  4. #4
    Low Bitrate wonderworm's Avatar
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    Anybody else out there have problems with their inverter similar to mine, possibly because they plugged in a cord backwards?

    I would think this would be a somewhat common problem for these things if reversing the polarity does mess them up since it's so simple to reverse the plug.

  5. #5
    Constant Bitrate P4_2.66GHz's Avatar
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    There no polarity in AC. AC stands for Alternating Current. In the US standard, it changes polarity 60 times per second, hence 60Hz.
    When they say reverse polarity on the inverter, they mean on the input, not output.
    The LCD's power supply is likely to be fully isolated, so you're good there.

    Something tells me you're simply overpowering your inverter, or there is not enough current/voltage supplied to it from your car's outlet.

    P.S.
    In a household, the long prong on the plug is the ground and the thin one is the hot one.

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