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Re: Locomotive current demands

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  • BJKRONEN@xxx.xxx
    ... There are two nightmares you can have with any model train in any scale: 1. Burn out the motor (with too high a voltage, or some types of pulse power) 2.
    Message 1 of 13 , Dec 31, 1999
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      Jeffrey and Bim:

      >Jeffrey: I suppose I'm not quite clear on what we're checking here though.

      There are two nightmares you can have with any model train in any scale:

      1. Burn out the motor (with too high a voltage, or some types of pulse power)

      2. Have a dysfunctional mechanism that gives you frustrating performance and
      overloads the motor until it burns out, or tears up the gears.

      The question at hand addresses the detection of # 2 before it is too late.
      With all my 12% knowledge I claim to have, I calmly put a brand new Marklin
      steamer on the tracks a year ago and watched it tear itself apart at a show.
      Dumb. Dumber than dumb. I "assumed" a brand new loco was properly oiled. I
      know better.

      What are some of the things that we have found inside locos:
      - - - - - - - - -
      Dirt and grime
      Excessive grease/oil - or - No oil at all
      Oil that has turned into concrete from age
      Strings, pieces of wire and springs
      Ballast, pieces of scenery, rolling stock, or even parts of the loco itself
      Unidentified gummy "stuff"
      Misassembled gear stacks, idlers, worms
      Brushes completely worn out
      Brushes far too tight on the commutator (acts like a brake on the motor)
      Screws
      Bent shafts and gears
      Animal hair
      Bad electrical connections
      , etc., etc., etc.

      No, we do not store our equipment rolling loose in the trunk (boot) of our
      cars. While they have clean storage, they run on layouts. Layouts always
      have some kind of loose "stuff" on them. There is no better track cleaning
      device known than a loco itself. If its loose, the loco will pick it up and
      digest it.

      I have bought locos from others which appeared to have been stored outside in
      a horse barn.

      The amazing thing, is that locos will desperately try to run with all this
      "stuff" inside of them. Or at least for a while. Until the motor or the
      gears give up.

      Anything on the list above, will try to prevent the motor from turning at its
      normal speed. This will cause the motor to draw more current. That can be
      seen on a meter, without a disassembly of the loco to check for all these
      problems.

      The idea is to see if a "benchmark" for normal current, at a specific
      voltage, under repeatable load conditions can be established for a quick
      check BEFORE someone puts a loco on the track.

      > Bim: What do you use to measure current???

      Most folks know that a volt meter measures electrical pressure expressed in
      volts. In order to make that measurement one puts the meter in PARALLEL with
      the power pack, the rails or the loco.

      In order to measure current, one has to put a meter in SERIES with the power
      pack. Since the polarity of the power back can be reversed, a "zero center"
      meter is appropriate. That means a meter that at rest, will have its pointer
      in the middle of the scale, and not off to the left side like most meters. A
      meter with 1amp-zero-1amp offers a usable reading, but can survive a dead
      short across the rails. Remember, any current (including a short) will pass
      through the meter on the way to the rails in a series connection.

      Likewise, a "zero center" voltmeter is quite appropriate too. Again, because
      the power pack can reverse the polarity to the rails.

      If interest develops, any one of several of us on the list can put together a
      list of parts from common (cheap) resources that folks can buy and use, with
      little or no electrical knowledge. A number of how-to books already have
      this information.

      But let's see if anyone agrees with the "normal" readings and the "test
      procedure" before we advance to that step.

      Who's next at the keyboard on this topic?

      Bill Kronenberger
      Houston
    • Ole.Rosted@xxxxxxx.xxxxxxxxxxxxxx)
      ... [snip] ... Me! But I m not at all sure, that my question is relevant in the context. - What about the inner resistance of the ammeter? Is it a specific
      Message 2 of 13 , Jan 1, 2000
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        On Fri, 31 Dec 1999 22:52:42 EST, you wrote:

        >From: BJKRONEN@...
        >

        Bill and group:

        >Jeffrey and Bim:
        >
        >>Jeffrey: I suppose I'm not quite clear on what we're checking here though.

        [snip]

        >Who's next at the keyboard on this topic?

        Me! But I'm not at all sure, that my question is relevant in the
        context.

        - What about the inner resistance of the ammeter?

        Is it a specific relationship between inner resistance of loco and
        ammeter that will produce produce the readings mentioned? And does the
        loco resistance vary with rotational speed - so that you will get
        varying milli-amp readings depending on the point where wheel-spin
        sets in (wheels and tracks not beeing 100% clean and friction/weight
        relationship)?

        I guess everyone will see immediately, that I do not know a lot about
        these things! But....?

        BTW: the lights on my locos only turns on at a voltage where the
        current consumption makes the loco rather hot?? (Marklin locos)

        regards Ole Rosted, Denmark
      • Ed Scullin
        To Bill B and the list. I don t remember seeing anything on whether or not the track should be level, and would it be possible to use wheel slip at a specific
        Message 3 of 13 , Jan 1, 2000
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          To Bill B and the list.
          I don't remember seeing anything on whether or not the track should be
          level, and would it be possible to use wheel slip at a specific angle?
          I have my test track with a hinge on one end and a jack screw on the
          other so I can see how a loco will do on a grade.
          Have you or anybody tried using the "cheap" digital multimeters from
          Radio Shack etc as the source of current reading?
          Is there any place (database) that we could put our data into, and all
          get at? Somebody that has a web site to act as a server, but I don't
          know about having external data input to a database on the net. Don't
          want to burden the web site owner with having to manually input
          everybodys inputs.
          Ed Scullin
        • BJKRONEN@xxx.xxx
          ... We just kept it simple. Flat and level for the wheel slip current test. I d suggest computing grades may be more than some folks want to get involved
          Message 4 of 13 , Jan 1, 2000
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            Ed:

            > I don't remember seeing anything on whether or not the track should be
            > level, and would it be possible to use wheel slip at a specific angle?

            We just kept it simple. Flat and level for the wheel slip current test. I'd
            suggest computing grades may be more than some folks want to get involved
            with.

            > Have you or anybody tried using the "cheap" digital multimeters from
            > Radio Shack , etc., as the source of current reading?

            Yup, and its a problem. Digital meters sample the current a few times a
            second and display the results. More you pay, more samples per second.
            Problem is, there are a lot of variables and the digital meters tend to not
            have a consistent reading, rather the numbers on the meter just bounce around
            like you were playing roulette.

            But good old analog meters tend not to do that, and the needle stabilizes on
            a fixed point on the scale, so you can read it.

            > Is there any place (database) that we could put our data into, and all
            > get at?

            What about the archives of the OneList itself? There are a number of folders
            already there.

            *** Jeffrey MacHan: How does that work, list owner? ****

            Regards,
            Bill Kronenberger
            Houston
          • John L. Battey
            Sorry if dredging up ancient history offends anyone ... ... though. ... pulse power) ... performance and ... late. A goal to which I aspire most vigorously!
            Message 5 of 13 , May 13, 2006
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              Sorry if dredging up ancient history offends anyone ...

              --- In z_scale@yahoogroups.com, Dec 31, 1999, 9:52 pm,
              BJKRONEN@... wrote:
              >
              > Jeffrey and Bim:
              >
              > >Jeffrey: I suppose I'm not quite clear on what we're checking here
              though.
              >
              > There are two nightmares you can have with any model train in any scale:
              >
              > 1. Burn out the motor (with too high a voltage, or some types of
              pulse power)
              >
              > 2. Have a dysfunctional mechanism that gives you frustrating
              performance and
              > overloads the motor until it burns out, or tears up the gears.
              >
              > The question at hand addresses the detection of # 2 before it is too
              late.

              A goal to which I aspire most vigorously!


              > > Bim: What do you use to measure current???
              >
              > Most folks know that a volt meter measures electrical pressure
              expressed in
              > volts. In order to make that measurement one puts the meter in
              PARALLEL with
              > the power pack, the rails or the loco.
              >
              > In order to measure current, one has to put a meter in SERIES with
              the power
              > pack. Since the polarity of the power back can be reversed, a "zero
              center"
              > meter is appropriate. That means a meter that at rest, will have
              its pointer
              > in the middle of the scale, and not off to the left side like most
              meters. A
              > meter with 1amp-zero-1amp offers a usable reading, but can survive a
              dead
              > short across the rails. Remember, any current (including a short)
              will pass
              > through the meter on the way to the rails in a series connection.
              >
              > Likewise, a "zero center" voltmeter is quite appropriate too.
              Again, because
              > the power pack can reverse the polarity to the rails.
              >
              > If interest develops, any one of several of us on the list can put
              together a
              > list of parts from common (cheap) resources that folks can buy and
              use, with
              > little or no electrical knowledge. A number of how-to books already
              have
              > this information.
              >
              > But let's see if anyone agrees with the "normal" readings and the "test
              > procedure" before we advance to that step.
              >
              > Who's next at the keyboard on this topic?
              >
              > Bill Kronenberger
              > Houston

              What I would like to do is set up dual meters (Volts & Amps) for each
              of my power packs, or integrate the meters into a Z Bend Track control
              connecter. Where would I get the information as to parts & assembly
              for this project?

              John L. Battey in Roanoke, TX
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