Need sensors for Fiber Cables !

Discussion in 'The Projects Forum' started by Resticted, May 17, 2013.

  1. Resticted

    Thread Starter New Member

    May 16, 2013
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    Hi,

    I'm looking for schematics of sensors that could detect the concentricity of fiber cables. Below is the defined application:-



    APPLICATION:-
    A Fiber cable plant manufactures cables, they recently had complaints about the eccentricity of the conductor. They need a sensor for that purpose which can detect whether the conductor is in the center or not. Now I want to design such sensor which could detect magnetic field in that stationary wire and on the basis of those fields, concentricity will be measured. The Company is already using some sensors for this purpose but they seem to have a lot of issues, that is why they are going for designing rather than buying it.

    NOTE: These measurements might be taken while the system is powered-off for security purposes.


    I have also attached the file of my objectives.
     
  2. wayneh

    Expert

    Sep 9, 2010
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    Since fiber cables conduct light, not electricity, there is no magnetic field.
     
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  3. Resticted

    Thread Starter New Member

    May 16, 2013
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    first i need to generate a magnetic field in a simple conductor. tell me how can i do that? i did think of using a ring core transformer.
     
  4. wayneh

    Expert

    Sep 9, 2010
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    Wrap magnet wire around a nail, pass current through it to turn the nail into an electromagnet.
     
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  5. davebee

    Well-Known Member

    Oct 22, 2008
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    At first I also thought of glass fiber, as in optical fiber cables, but I suppose a strand of copper can be considered a fiber, too.

    Maybe a laser beam could penetrate the insulation enough to form a shadow of the inner conductor.
     
  6. wayneh

    Expert

    Sep 9, 2010
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    Or an X-ray. But I'm still not sure we understand what is needed.

    If you pass current through the cable, I wonder if you couldn't configure a magnetic field that centers the conductor. You could then "know" precisely where the conductor is and visually see where the insulation is. Tough to eliminate mechanical artifacts. Just thinking out loud.
     
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  7. Resticted

    Thread Starter New Member

    May 16, 2013
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    Thanks Wayneh and davebee, your replies gave me an initiative. Now I'm left with 2nd objective which is to detect that magnetic field. What type of sensor I'm required to use? Whatever the data collected will be sent to the control unit for checking the concentricity. Can i use frequency for concentricity detection? just curious...
     
  8. Resticted

    Thread Starter New Member

    May 16, 2013
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    In simple words, i need a method to find out the concentricity of the conductor from that field...
     
  9. wayneh

    Expert

    Sep 9, 2010
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    I wonder if you could put a small magnet on either side of the conductor under test, pass current through the cable, and then measure the deflection of the magnets. The magnets could be oriented to be repelled by the cable's field and the distance they move might give an idea of how well centered the conductor is inside the cable.

    This would need to be built to the precision of an analytical balance and would need calibration. A lot of hard work.

    X-ray sounds a lot easier. I'm thinking of how easily they take dental x-rays.
     
  10. tubeguy

    Well-Known Member

    Nov 3, 2012
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    What if you you put an AC signal through the center conductor and detect with 3 equally spaced wire wound sensor's (like ferrite core antennas) around the conductor, as in a buried wire detector ?
    Could that be used to detect the center conductor position ?
     
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  11. Ramussons

    Active Member

    May 3, 2013
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    This seems the workable solution. Once you calibrate the sensors, you should be able to do a real time check on the "flowing" conductor.

    Ramesh
     
  12. strantor

    AAC Fanatic!

    Oct 3, 2010
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    You guys have boiled it down to almost exactly how it's done in industry. A current is induced into the conductor with a torroid, and then a little ways down the line a sensor of some sort (hall sensor, not sure?) coupled with a laser micrometer resolve the absolute center of the conductor based on the induced current and compare that with the measured position and diamater of the extruded exterior to determine eccentricity and wall thickness.

    I work in the Wire & Cable industry, and I have installed systems by Beta Lasermike (Center Scan system with DataPro 5000) and Sikora (Centerview 8000 system with Ecocontrol)- the 2 most respected names and systems in this niche. They are both highly advanced and very expensive (>$80K). They are the Ferraris and Maseratis of the conductor eccentricity measurement world and still they are not perfect. They are very picky and will give faults or incorrect measurements if conditions are not perfect. The conductor must be aligned with laser precision through the measuring device in 3 axes and be steady as a rock or you will have problems.

    Regarding the instruments you already have; Install copious rollers to eliminate floppy conductors and align the conductor perfectly through the measuring instrument.

    I do not mean to be a bummer, but if you had to come here just to get a working theory of how such an instrument should be designed then I do not think that you have what it takes to build something that works better than what is already available. You are wasting your time. Fix your process and if that doesn't do the trick, buy a better instrument.

    Also, this doesn't work for fiber, as already pointed out. An if you're considering this a "stepping stone" to a similar devices that works for fiber, you're barking up the wrong tree. You are going to need a radically different approach. Read this.
     
  13. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Don't know about the torrid and current measurement part, because I never got that much into it. But the Lasermike is the way it was done where I worked too. The bare core was kept taught and measured then the extruder started and the head was adjusted to keep the insulation centered to the bare core base line.
     
  14. Resticted

    Thread Starter New Member

    May 16, 2013
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    @Strantor : before to post this issue on this forum, i designed and experimented few methods to achieve the objectives which includes SIKORA Centerview 8000. But due to faults in measurements i couldn't continue with it. All the suggestions and methods posted by all members on this topic have already been tested and implemented by me. Due to accuracy and precision i cannot go for built-in technology.Thank you all for your suggestions and comments !
     
  15. strantor

    AAC Fanatic!

    Oct 3, 2010
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    So you have a Sikora Centerscan 8000 and you can't get it to work properly?

    Is it because you're trying to use it on fiber optics? As discussed, this type or any related technology will not work without a electrically conductive conductor.

    If you are saying that the Centerscan did not work with your copper conductors then it is possible that there is an issue with the Centerscan, although I still suspect an error in your process. The centerscan aligns itself with servos in 2 axes, you only need to make sure that it is aligned exactly in the 3rd. The conductor must be grounded on one end and one end only, for the centerscan to work. The centerscan and its torroid must be very well grounded to earth. The lenses inside must be absolutely free of dust and debris, cleaned with isopropyl alcohol and lint free wipes. If everything is good to go, have a Sikora tech come out; this thing should work. I've seen it work flawlessly and I have faith in it.
     
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  16. Resticted

    Thread Starter New Member

    May 16, 2013
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    No i wasn't using it for fiber in fact i never really did. And i got the error it was in servo's alignment, and the lenses were quite dusty. Rest is perfect. Thank You !
     
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