Experience with bus based power systems?

Discussion in 'Electrical Systems' started by Nordic Cat, Oct 11, 2008.

  1. tanjera
    Joined: Jul 2009
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    tanjera Hennie

    If you paid attention to my post I said I was not sure how you can forget about wiring with empirbus - it still needs wiring and my point is that it would need a whole lot more than MWS as desribed in www.yachtwiring.com
    What is the sense in a distributed control system (on an average size yacht) if one controller switches 32 circuits? You still end up with lots of wires (albeit thinner ones) all over the show!
    Please look at the website before you comment again.
    Happy wiring
    Hennie
     
  2. apex1

    apex1 Guest

    Well I did´nt look at that before today. But it is just another Bus system, there are many good, some not so good and only a few well proven on the market. The best proven by so far is "Empirbus" with the most installations in the commercial and recreational market. And (of extreme importance) best proven software. Look at the Calder article in recent "professional Boatbuilder" issues, he installed "Capi2" (a good system by Victron) and had several problems.

    So please forgive that I hammered on your head senseless and without following your link first.

    Richard
     
  3. Stumble
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    Stumble Senior Member

    Hennie,

    I am not sure if I understand your objection, but I think you are objecting to one button controlling 32 circuits as this would require bringing 32 positive and negative wires to the switch. Assuming this is what your objection is to the distributed system you are mistaken in the way a distributed power buss system works.

    Instead of having to feed the +/- wire through the boat there is one main trunk pulled bow to stern that every point is attached to. Ideally at the closest physical location between the point and the wire, though in practice there may be some variation due to accessability. So the Nav lights in the bow are making a 3' run to this trunk line, the cabin lights in the stern are making the same 3' run ect. All of the +/- cables from the points connect to a relay and from the relay to the main trunk.

    Running right next to the trunk line is a small low voltage data cable, basically a phone line that connects from every relay onboard to the control panel (or panels). When a switch on the control panel is turned on there is a digital data signal sent nown the network to turn on relay numbers X, Y, Z no matter where they are.

    The effect of this is that the control panel doesn't need to be actually wired to the power cable, and that the definition of the switches on the control panel can be changed to alter which relays it turns on. So if you wanted a switch that turned on every relay in the boat, that could be wired to just one switch, down to each relay being controlled by a different switch. The control box then only needs the data cable run to it (though it may also be tied to the trunk line for its own power), not the hundreds of wires and supply cables that a traditional instalation would need.

    So as an example for a bow thruster that would normally require 00 wire run from the thruster in the bow, to the breaker panel amidship, then to the battery, then back to the bow thruster. on a 50' boat this run is likely to require 60' of cable possibly more. On a distributed system you would have a trunk line of say 000 gague wire running from the batteries forward and dead ending there. Alongside the 000 wire is a phone cord. Where the bow thruster attaches to the trunk you have a relay, then a 0 gage wire from the relay to the thruster, and the phone cable running from the relay to the control box (note that all sizes are made up since I don't know the sizes you would need off hand).
     
  4. tanjera
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    tanjera Hennie

    Hi Richard.
    Thanks for looking at the system. I have investigated quite a few of these with the view to installing one myself. I think I can answer the software issue by stating that the owner of MWS is the founder of a very sucsessful software house that, amongst others also designed and maintains all the commodity trading software for the JSE. He is also a qualified Mech & Elec Eng. I have been sailing and motoring on two boats with this system (one has been commisioned three years ago) and am very impressed. It certainly is worth a second look if one is in the market for such a system.

    Capt Rubin,
    My argument is based on the fact that, having one unit that controls 32 outlets, one is almost back to a centralised system in so far as this controller will invariably be mounted far away from most of the items it controls. Furthermore if something goes haywire, as it surely will, a lot of circuits will be influenced.
    The MWS system only has 3 relays per unit and as such can be placed closer to where it is needed. The software is downloaded into each individual unit that then operates autonomously once programmed. If something goes wrong one only has to replace one unit (of 3 relays) which is considerably cheaper than the Empirbus unit. You also have the ability to easily bypass the unit completely with a fused and switched bridge and effectively operate in 'manual' mode without any loss of functionality.
    Troubleshooting this system is also made a lot easier by the fact that only three outlets are controlled per unit.
    I also like the fact that all the electronics are 'potted' and thus a lot better protected from the vagaries of the boating environment than Empirbus with exposed (relatively) PC boards and connectors.
    In terms of cost effective expansion it also has a distinct advantage over Empirbus because it can be done in small increments instead of 32 at a time. In my opinion Empirbus is a system designed for much larger boats and has its place in those applications.
    Lastly I agree with Richard that there are quite a few of these around and one should do one's homework before committing to a system.
    Regards
    Hennie

    PS I just recalled an interesting event: The owner of a new 46 ft power cat (four 300hp Suzuki outboards) had some problems during commissioning (builder did not follow installation instructions) and MWS sorted the problem via the internet. They traced the wiring fault and after it was rectified managed to test and control all systems remotely.
     
  5. apex1

    apex1 Guest

     
  6. apex1

    apex1 Guest

     
  7. tanjera
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    tanjera Hennie

    Richard
    If I remember correctly each PC board had 8 channels and each controller takes a max of 4 PC boards.
    Where Empir really falls down is when you start comparing costs.
    Regards
    Hennie
     
  8. wardd
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    wardd Senior Member

    but i like speaking tubes and engine room telegraphs

    dont get me wrong i build my own computers to get what i want, but out where its lonely i like the idea of some tape, a roll of wire and a ohm meter, a few extra switches and fuse holders to get me where i want to go
     
  9. tanjera
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    tanjera Hennie

    IMO the MWS (and others) allows you to do exactly that - it is just so much easier to do fault finding and by-pass the fault.
    As I said before all you need with MWS is a jumper lead with a suitable inline fuse and switch and Bob's your uncle - problem solved.
    The only applications for the computer is the initial downloading (or up grading) of the software, data collection functions and optional switching from the computer. If the smoke comes out of the computer it is no train smash - everything except data collection still works.
    Hennie
     
  10. apex1

    apex1 Guest

    Hennie, I never compare just cost. And luckily my customers do´nt do so either.
    When we talk boats we talk trouble, a proven system and a wealthy supplier with a reliable service is more important than a purchase price. There my supplier shines!

    Do you mean this:
    [​IMG]

    when you say "PC boards" ?
    Thats the slave module, and that has proven to stand the marine environment.

    Richard
     
  11. tanjera
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    tanjera Hennie

    Hi Richard
    Yes that is what I was refering to - sorry for the wrong name, but you got the idea. Compare that with a well designed potted system I know which one I will go for!
    I wholly agree that one should never make a decision based on cost alone, however I have often ended up buying the more expensive of two items just to discover later that, inspite of a big price differential, it has the same crap inside as the cheaper one!
    It is a fallacy to think that one product is better than the next because it is more expensive!
    When the customer pays it often is to the advantage of the consultant, advisor, salesman, whatever you want to call him, to sell the more expensive product and they then find that they have to 'invent' all sorts of seemingly good reasons to justify the reccommendation. I am not implying that you are in any way doing that, but I have seen it happen time after time.
    Anyway all of the above is not applicable to the normal yachtie that has to figure things out for himself, install it and live with the consequences. To us value for money makes a big difference and when two products of otherwise similar attributes are compared we will always go for the cheapest. In this specific instance I will personally not even consider Empirbus just because of the costs involved for a small system (say 42 circuits).
    I cannot let your comment about a 'wealthy' supplier stand without noticing that they needed to bring in Venture capital and dillute their shareholding in order to keep up with development costs!
    Lets keep an open non-biased mind and look to see what their new NXT System is like.
    Regards
    Hennie
     
  12. wardd
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    wardd Senior Member

    usually the quality is in the layout, case and programming not the components as they are usually off the shelf
     

  13. pamarine
    Joined: Sep 2009
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    pamarine Marine Electrician

    I know I'm a late comer to this thread, but Cole Hersee also makes a Bus system (I believe it is called Minibus). Similar systems are found commonly in RVs.

    I wil try to read through the thread a bit more and give a more detailed response at a later time.
     
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