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Autocad Electrical best product for electrical "loop" sheets?

Discussion in 'Electrical Engineering' started by [email protected], Nov 18, 2003.

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  1. Guest

    I use Mech Desktop and Inventor..... and have little
    experience or understanding of electrical schematics.

    However..... my boss is trying to create electrical
    "loop" sheets for PLC automation using plain jane
    Autocad.

    It seems very cumbersome doing this. Basically like
    using Autocad as an Etch a Sketch.

    Would "electrical" be a much better "tool" for what we
    are trying to do?

    And..... some general questions Id like advice on. If
    doing electrical schematics in plain Autocad... should
    one NOT use paper space for the text and border.... and
    instead keep everything in model space?

    John
     
  2. weco

    weco Guest

    I use Via Lite...
    The old version has its limitations but for what we did it was ok...They got
    bought up by autodesk (go figure) and are now marketed by them.
    If you do enough work to justify it they may be worth looking at if you
    already own Acad anyway. I would never buy acad for that purpose tho...

    In my experiance there is never enough time, and doccumentation is one of
    those tasks that gets under estimated, short circuited and pre-empted.
    To use Acad basic for this seems to me to be a real problem if you plan to
    do it in the course of buisness... If you wanna do it now and then well
    thats differant...

    I dont know about you guys but I hate paperwork, and making that rtask
    easier is ALWAYS my goal....

    my 2 cents worth

    henry
     
  3. Guest

    I would never buy acad for that purpose tho...

    So what would you use for loop sheets?

    Is Visio just as good or better?

    John
     
  4. Guest

    Pardon my ignorance, but what is a "loop sheet?

    Well I hate to admit this.... but I really don't know
    either.

    Maybe someone will chime in and explain how loop sheets
    differ from ladder logic schematics?

    John
     
  5. Louis Bybee

    Louis Bybee Guest

    A Loop Sheet, in the context I believe your are using it in, is associated
    with individual, or multiple, control circuits. It can be represented in a
    few different ways. It could a diagram of one individual loop, or the loops
    of a complete system, or a number of interrelated systems. They could also
    be presented in a few different formats. There is usually additional data on
    the loop sheet relating to the loops, or circuits represented. That could
    include, but not limited to, specs. on loop instruments, splice or
    termination points, set points (temp, flow, and pressure, settings),
    location of instruments, and other data pertinent to the loop, or system.
    The loop sheet is necessary for tuning, trouble shooting, maintenance, and
    changes to the process being controlled.

    An example of a simple loop sheet for a system could be a tank with product
    being drawn out for a manufacturing process. The factors needing control
    might be the amount being drawn out and at what rates, the amount being
    replaced and the rate needed to keep the tank at a constant level with the
    tank influent being a mixture of multiple liquids each needing to be added
    at a specific ratio while being supplied at different and changing
    pressures, the possible need to keep the tank contents at a specific
    temperature, and all these variables needing to be kept within a tight
    tolerance to meet some standard, or risk substandard production of the end
    product.

    A loop sheet could be equated to a schematic, or print of an electrical
    system, and would be just as useful, or useless, depending on if its been
    kept up to date or not, and the ability to locate it at a moments notice
    (it's 3 AM - all the managers and engineering staff are away from the plant,
    liquid is spilling from the overflow of multiple tanks, the maintenance
    staff can't access the loop sheets because the manager keeps them locked in
    his desk in his locked office, and the process could become extremely
    unstable, might be hazardous, be worth thousands per gallon, or take weeks
    to restart production if it isn't shut down properly).

    Working on a complex, or even some simple, control systems without loop
    sheets would be like a doctor having orders to do an amputation, and not
    being given the information as to which appendage needs to be removed, and
    being told, "oh, he's in there", accompanied with an arm gesture towards the
    hospital. :-] Hey don't laugh, it happens!

    Louis--
    *********************************************
    Remove the two fish in address to respond
     
  6. Guest

    Working on a complex, or even some simple, control systems without loop
    Thanks for great reply!!

    Question tho..... do loop sheets "replace" ladder logic
    schematics?

    Or are they used in "conjunction" with them?

    John
     
  7. Louis Bybee

    Louis Bybee Guest

    For the most part they are different worlds.

    Ladder logic schematics tend to represent an off - on, or digital world. For
    example a home heating thermostat is measuring an analog quantity, and its
    output is digital off - on. There is a limited artificial intelligence
    capacity with ladder logic components (with minor exceptions). Ladder logic
    schematics are more discrete in nature showing subcomponents of a device
    such as a relay contact.

    Loop Sheets represent devices in an analog word, components are represented
    as assemblies (individual internal components of the part aren't usually
    shown), and most often consist of analog output sensors, analog controllers
    with varying levels of intelligence and complexity, and analog input control
    devices. Loop sheets are drawn, and represent components more in a block
    format like a logic flow sheet.

    Comparing the two is like the correlation between an a kid's wagon, and
    computerized package sorting conveyor system you might find at a UPS
    Distribution Center. They are both capable of transporting packages, but
    there are rather unique differences.

    Louis
     
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