What are my options for accomplishing 480V 3 Phase branch circuit protection?

Discussion in 'Power Electronics' started by ma77ken7, Dec 6, 2017.

  1. ma77ken7

    Thread Starter New Member

    Dec 6, 2017
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    0
    Hi,

    Designing a system that needs to distribute power to several motors at once. Motor quantity is highly variable and can range from 1 to 20 in a single system. Motors are 480V 3~ and are around 6kW. The biggest issue I'm facing is physical space of the components and how to solve branch circuit protection for wiring to motors. I am a mechanical engineer and very comfortable with general electrical work, but have very little knowledge in electronics design. My main question is, am I limited to designing around standard electrical panels and din rail mounted components? Or are there other components out there that would enable someone to design custom electronics at this high of power?

    Thank you
     
  2. Picbuster

    Active Member

    Dec 2, 2013
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    75
    Use frequency / motor controllers and sync them. ( like Siemens, Eaton ).

    Picbuster
     
  3. tranzz4md

    Member

    Apr 10, 2015
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    50
    #1:No
    #2: yes

    So, there are typically 3 general schemes; MCCs, Distributed individual motor controllers, and custom control cabinets.
    --MCCs are most practical for integral horsepower and larger motors in groups up to 50.
    -Distributed is practical for indoor, in-plant installations of integral and fractional horsepower motors, and where changes are expected, but not substantial in sizes.
    - custom control cabinets are most typical and practical for integral and smaller motors, and where substantial changes in power bearing components are not likely.

    I got very useful information, references, referrals, and help when I did some of my first systems years ago from my local Square D affiliated supply house (I think they're known as Schneider these days) but at least here in the USA, you're best off finding your local Electrical supply house that has the reputation for supplying industrial work.
     
    Reloadron likes this.
  4. tranzz4md

    Member

    Apr 10, 2015
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    Your use of those terms, as well as "branch circuit" and "branch circuit protection" and motor sizes in kW,,, well, seem to surf a wide spectrum.

    You won't be designing custom electronics for branch circuit protection,,, or custom electronic branch circuit protection. "High power" probably does not apply to your application, at least in the view of anyone familiar with industry, 480v motors, 3-phase power, or motor controls.

    Designing a system with one motor and capability and capacity to simply add 19 more is probably not what you're suggesting, but,,, it's not really clear what typical configurations might be.

    The size of the physical area over which your motors and associated sensors and devices are spread are also considerations.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    It begs the question that if you are not proficient in this area, why are you in the position of designing electrical distribution systems?
    It appears you are looking for an 0ff-the-shelf solution, which in most cases of custom applications, there is none.
    Also, what is wrong with "designing around standard electrical panels and din rail mounted components".
    Here the NEC/CEC and NFPA79 is used as a reference.
    Telemecanique and Siemens also offer design circuits and methods.
    What is the country you are practicing in?
    Max.
     
  6. ma77ken7

    Thread Starter New Member

    Dec 6, 2017
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    We are a small manufacturing company in the US, with less than 20 total employees. Many of our team members wear several hats, as we are still in an aggressive startup environment. We currently outsource our control panel manufacturing but would like to put more thought into a particular design that we feel could make a huge difference in our product. We have not needed an experienced person in this field up until this point, which is why I am exploring the idea myself to see which direction we should go. We understand the purpose of general panel design for equipment, but for what we are specifically trying to accomplish we feel that it is not a good fit. We see our design as more of a product itself, which we have already had the current panel design ETL listed. Our goal would be to create an electrical design of our own that we would list, brand, and patent as our own product. We are not convinced what we are conceptualizing is feasible and that is why I am trying to gather as much information as I can in order to decide where to turn our focus. If you were to build a prototype/proof of concept for a product using general panel construction and components, where would you go from there in order to design the necessary circuitry and hardware needed to build a more unique solution? This question is primarily challenging to us due to the specific power requirements we are working with and having no examples of similar designs to learn from.

    Thank you
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I would have to know a lot more such as the nature of the equipment and the environment it will eventually be used in, including the end purpose.
    Also what is the reason for wanting a unique method of control, instead of using established tried and true techniques?
    Max.
     
  8. ma77ken7

    Thread Starter New Member

    Dec 6, 2017
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    For the specific task we are trying to accomplish, the tried and true techniques seem too bloated, cumbersome, and transparent. We would like full control over the utility, circuitry, shape/construction, ergonomics, etc. We see it as more of a product design but maybe this sort of electronics is more niche than we expected? What lies between PCB and Din rail mounted electronics? Or is it PCB that we are working towards? If so, where do you source components for such a design?
     
  9. tranzz4md

    Member

    Apr 10, 2015
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    It appears that a PCB may well be what you'd most practically and logically move toward. Speaking just toward the power wiring and components, you've certainly seen embedded fuses, circuit breakers and overloads. You definitely don't need to have lots of DIN rail mounted stuff, but you must have the proper overload and overcurrent protection, and those devices must meet well established standards, and be listed, and it is absolutely unseen for equipment manufacturers to make their own. Go inside ANY electrical utilization equipment on this planet, orbiting it, or from it, and you'll find those components are manufactured by one of perhaps 12 different manufacturers. On the control side of things, you must be aware of the global shift toward "open source", but you may well wish to do your own thing.
     
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
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    You design a PCB for all the components suitable for integrating into this format, using Schematic capture program such as the free Kicad to higher end such as Orcad etc. The resultant board files are sent to a PCB manufacturing facility which can either supply a unpopulated version for you completion, or will manufacture the whole board.
    You then source a suitable enclosure supplier such as Hoffman etc, The hardware component such as contactors etc I would source DIN style such manufacturers as Telemecanique etc.
    Max.
     
  11. Reloadron

    Well-Known Member

    Jan 15, 2015
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    1,061
    I will share a few thoughts with you. Three phase motors even in a 480 VAC flavors come in a wide range of sizes and HP ratings. When we want to do things such as monitor the power to these motors we can look at things like over and under voltage on the bus. Then we might want to look at things like phase loss on the bus. If we monitor those parameters we need to decide what do do under situations like phase loss or over and under voltage? Maybe we want to look at the phase current by individual motor? Possibly motor frame temperature? When considering hardware and software solutions for monitoring large or small motors I think the best way to approach it is using a clean white sheet of paper and a sharp pencil, it also helps to have an eraser. Start with the primary bus and list all the parameters we wish to monitor followed by each motor and what parameters we wish to monitor.

    I think you will find that some parameters are best and most economically monitored using turn key out of the box solutions including DIN Rail modules while other sensors will be, while turn key, off the DIN rail in a motor control cabinet. Building custom tailored solutions is an option but you really need not reinvent the wheel either. It is nice to keep things uniform and have spares on the shelf if something fails, be it an in house design or off the shelf turn key solution. Finally budget plays a roll in the entire process. Small start up companies do not always have the deep pockets of their larger counter parts.

    Ron
     
  12. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Also if there is any kind of logic control, A small PLC could be considered, also for control level voltage I would consider 24vdc as this has become the general standard for control voltage now.
    Also contributes to less loss of inductive control devices, coils s0lenoids etc, as compared to AC.
    Obtain a copy of NFPA79.
    Max.
     
    Last edited: Dec 10, 2017
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