Earth fault detection system

Discussion in 'General Electronics Chat' started by champ1, Apr 16, 2019.

  1. champ1

    Thread Starter Member

    Jun 4, 2018
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    Hello

    In the case of safty, I would like to make a system to find earth faults within the system. I think I have to use microcontroller and sensor

    Anyone have done this before
     
  2. mvas

    Member

    Jun 19, 2017
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    Are you going to monitor the imbalance of current between the Hot wire & the Neutral wire?
    You could use a microcontroller or an analog circuit.
    Delta 5ma Trip ?
     
    Last edited: Apr 16, 2019
  3. Yaakov

    Well-Known Member

    Jan 27, 2019
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  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Re-inventing the wheel?:confused:
    RCD or residual current device are common.
    Max.
     
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  5. champ1

    Thread Starter Member

    Jun 4, 2018
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    Do you know any circuit?

    What we need with microcontroller to make this type of system ?
     
  6. champ1

    Thread Starter Member

    Jun 4, 2018
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  7. shortbus

    AAC Fanatic!

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  8. MaxHeadRoom

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    So what more do you require of it?
    Max.
     
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  9. champ1

    Thread Starter Member

    Jun 4, 2018
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    Will it prevent from electric shock? if yes then what's the difference between this IC and MCB?

    I want to make the system in which ground fault detect, one buzzer should be ringing an alarm. Generally buzzer work between 3V DC to 24V DC. So Do we need a microcontroller to make a complete system?
     
  10. DickCappels

    Moderator

    Aug 21, 2008
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    When it comes to personal safety I would not rely on a one-off hand built ground fault protection circuit. Ground fault breakers are inexpensive and easy to use, and besides that a lot of work goes into commercial devices to assure that they work correctly and consistently.

    If you are doing this as a learning exercise and as long as you don't bet your life on it working correctly every time, that is another matter and you can even use a microcontroler in it.
     
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  11. MaxHeadRoom

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    Using a standard GFI or RCD, use the output for a suitable relay, when power fails a N.C. contact could energize your alarm.
    Max.
     
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  12. shortbus

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    What you really should want is something that shuts down the power. The breaker you linked to does two thing, shuts off power on a ground fault and protects from an overloaded circuit, both at the same time. Putting your or anyone's life in the hands of a homemade devise is irresponsible in the least and criminal in the most. But it's your choice.
     
  13. MisterBill2

    Distinguished Member

    Jan 23, 2018
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    The simplest ground fault indicator system is what we used for every control cabinet at a GM plant a few years ago. The controls power was 120 VAC, NOT grounded, and the ground fault detector was two 120 volt pilot lamps in series across the isolated power circuit, with the common between them tied to the system green wire ground. Any circuit connection from the isolated control circuit to ground would illuminate one light brightly and darken the other one.
    BUT if the TS wants a ground fault interrupter that is different. And please note that not one word of description about the system is mentioned. It could also be 12 volts, 24 volts, or 220 volts..
    The GFCI will not give any warning until unbalanced current flows.Then it switches off, and still gives no warning indication.
     
  14. Janis59

    Active Member

    Aug 21, 2017
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    RCD system (we speak Differential Current Automat) is wonderful thing and cheap, it is worth every cent You spend on it obtaining, however I cannot use it in my home. Have no solution how to. After installing it to the bathroom, where it is most needed because all electric boilers sometimes may give an electric leak, in time of few months the whole earth wire is melted. Changed, after month again. Just measured voltage between water pipes and grid gnd - about 1 or 2 Volts. Measured current - about 100 Amps (not miliamps!). I cannot to do there anything.
     
  15. MisterBill2

    Distinguished Member

    Jan 23, 2018
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    If there is that much current flowing in the "earth" wire, which I am guessing is the same as the safety ground connection here, there is indeed a big problem. 100 Amps is far more than should be flowing in any system, and indicates a major problem, such as a reversed line and neutral connection. And if the circuit protection device, fuse or circuit breaker, is not rated for that much current but is not tripping, then there is another problem in that the current is from a different source. So at this point one choice is to investigate at the distribution point and see why there is any current flowing in a ground wire, because something is seriously wrong. Is this system in an individual residence or in an apartment building? Do you have access to the fuse panel, or not?
     
  16. Janis59

    Active Member

    Aug 21, 2017
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    I have, but read please carefully, the VOLTAGE is only 2 Volts. It excludes any least suspicion on mistake. Simply water network and electric network in my street-bloke seems are using DIFFERENT "Earthes" so my thin wire between them are acting to balancing it. Logically, I wrote the claims until just tired. Only answer was - do You have personal licensed expert number if You want to have ANY claim about networks. At least now I know that even at full short I never will have on the pipes more than 2 Volts.
     
  17. MaxHeadRoom

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    That certainly points to the neutral being open before the service panel, hence return path is through earth return to the supply transformer grounded neutral point.
    Max.
     
    Last edited: Apr 19, 2019 at 2:43 PM
  18. MisterBill2

    Distinguished Member

    Jan 23, 2018
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    OK, now understand the situation.The neutral to the building is evidently not connected to the water system ground adequately.And the current that flows through the connection that you provide, which melts that connecting wire, as you state in post #14, is delivered by the external electrical system.
    So the frame of your water heaters is connected to the electrical system "earth" wire, as well as the water pipe. So now here is a question: Does the water heater power connection have both a line and a neutral connection, in addition to the earth connection? OR is the power to the water heater applied between the line connection and the earth connection?
    "Only answer was - do You have personal licensed expert number if You want to have ANY claim about networks." tells me that the people in charge of the electrical distribution system know that they have a big problem but they refuse to try to fix it because they do not know how to fix it, or it would cost some money to fix the problem.
    The problem with the electrical distribution network is that the resistance in the neutral circuit is excessive, probably because the wire size is too small for the current flowing. The solution is for the electrical utility organization to spend the money to provide adequate distribution wiring.
     
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