automatic shutdown circuit for reversed polarity shore power hookup?

Discussion in 'OnBoard Electronics & Controls' started by sdowney717, Jun 22, 2013.

  1. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    Please stop experimenting with shore power yourself, it may get you killed!
    Instead, ask someone with basic knowledge of electricity to install whatever you think you need.
     
  2. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    Listen you just can not get around the 25,000 ohm impedance issue which is bonding neutral to ground using a transformer or this polarity alarm.

    Even rectifying the output of a 12v transformer to run the dc coil on the relay still leaves the primary joining neutral to ground at about 300 ohms.
    And then leaving the buzzer in the neutral to ground circuit is going to lower this further, technology must have moved ahead in this area since 1970.

    I am still alive and learning all the time.

    I may post this on an electronics circuit forum for some more ideas.
     
  3. CDK
    Joined: Aug 2007
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    Likes: 146, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    For all I know you may be a brain surgeon, a lawyer or a microbiologist, but your questions tell me you surely have no background in electricity.
    I do encourage studying and experimenting for anybody who is interested in it, but the power grid is the wrong place to start.
     
  4. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    Be honest, you did say

    Which which wont do a thing.

    neutral line - rectifier - ground

    So your words are not well put and confusing. And as I read them made no sense to me. What you meant was a rectifier on the transformer output to make DC to power the relay.

    I can do all that, I can make a functional circuit.
    But there will be a neuttral-ground connection with less than 25,000 ohm impedence. So If the ground wire breaks or gets real high resistance, amps will want to flow from a ground wire back to source and that may include your body if you touch ground wire and the water.

    I am not totally ignorant like you think. I have wired up 2 homes with mains, panels and all circuits. And I took 3 years of electronics in high school. Been working on others electrical projects and reading, fixing and playing with electronics for about 30 years now. Yeah not so much of an electrical engineer but I do know some things.

    What is needed is a high impedance switching circuit to drive the relay so that ground and neutral wont have a resistance connection between them less than 25,000 ohms. If the cruiser forum electronic admin whiz is correct. Likely many people have these type old alarms and no longer meet the standards.

    I personally think that cruiser forum is full of goofball elitists and I don't post there anymore using my old name.

    http://www.jamestowndistributors.com/userportal/document.do?docId=91
    Also mentions the shock risk as I already stated IF you have less than 25000 ohms resistance which is about 4.5 milliamps power flow only.

    [​IMG]

    If I leave my old alarm in the circuit or add in a transformer, I am creating a shock risk. Interesting that since 1970 till about a year ago, that sonic alarm of 500 ohms has remained in the circuit creating a genuine shock hazard for over 40 years and no one has been shocked yet. I am the 5th owner and I wonder how many other boats have something like this and do not know it can shock them?

    I have hooked up the old neon light which still meets the new rules.
     
  5. Mark Cat
    Joined: Jun 2011
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    Location: Michigan

    Mark Cat Senior Member

    Per ABYC shore power connect / disconnect must follow the shore power warning label located at the vessel power inlet. The same procedure is included in the vessel operators manual.

    The procedure and the vessels shore power approach, is designed so anyone can connect to shore power if the instructions are followed.

    I like to add a step which requires visual inspection of the inlet, cord and pedestal, for damage or burn marks.

    To pass an electrical survey, the vessel will have to be ABYC compliant for shore power connection.

    All for now,

    Mark Cat
     

  6. sdowney717
    Joined: Nov 2010
    Posts: 852
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    Location: Newport News VA

    sdowney717 Senior Member

    I found out you can use an EL817 of which I have a bunch
    http://www.mouser.com/ProductDetail/Everlight/EL817/?qs=vs%2bWWTB4QKYUQzCxB0orLQ==

    An optical photoconductor photo transistor has an led light diode on one side and turns on a transistor switch on the other when the LED lites up.

    This can be used in place of the high impedance led light that you see.

    The photo transistor can be driven with a 25,000 ohm resistor in the neutral to ground line.

    This photo transistor isolates two circuits. The other side would have to have power amplification by a transistor to run a relay.

    the photo transistor is just like an LED light, but you do not see the light being within the device. It turns on the transistor to conduct current, so light on, current conducts and you just have to design the right circuit to do what you wish it to do after a reversed polarity phase condition.
    Such as showing the reverse polarity light, sounding the audible alarm, turning off my boat 4 pole power relay.

    If I get around to a working design, or someone on the other forum shares a design, I will post the circuit.

    Like so many things, limited time, right now having to replace my cars AC compressor.
     
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