Archive: Electrical systems

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  1. Archive
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    Electrical systems
    NOT COMPLETE! -- TerryKing 18:24, April 10, 2007 (EDT) This Wiki Page is intended to align with the section on the boatdesign.net Forums: CONSTRUCTION > ELECTRICAL SYSTEMS.

    What it is NOT:
    • Complete.. Much #TODO#
    • Coverage of shipboard electronic devices themselves
    • Coverage of Onboard Computer Systems (See existing Wiki Entry for this)
    What should it cover?? (Please contribute!) Use the "Discussion" tab above. Or edit it yourself!

    General Discussion
    Although this is a construction-oriented page, it should be applicable to upgrading or troubleshooting existing installations.

    Electrical Safety
    This is the most important part of this subject! A boat is the worst place in the world to have a fire or serious injury - you have nowhere to run, and emergency services are far away.

    Published Standards for Shipboard Wiring
    Boating is a world-wide activity! We need to collect relevant standards from Europe and the Far East as well as the US.

    United States Coast Guard
    U.S. Coast Guard "Boatbuilders Handbook" This is a link to a page with downloads for all the different parts of this useful publication which includes requirements for many different aspects of Boatbuilding and Safety.
    Download (PDF) The "Electrical Systems" section of the US CG handbook

    American Boat and Yacht Council

    These standards are guides for the design, construction, and installation of direct current (DC) electrical systems on boats and of alternating current (AC) electrical systems on boats. ( ABYC standard E-11 removed from WIKI due to ABYC copyright )

    Transport Canada
    Small craft built in Canada must conform to theConstruction Standards for Small Vessels (TP 1332 E). Electrical systems are to be designed to meet or exceed the requirements set out in Section 8 of that document.
    ISO TC 88
    The International Organization for Standardization (ISO) Technical Committee 88 publishes standards relating to Standardization of equipment and construction details of recreational craft, and other small craft using similar equipment, up to 24 metres length of the hull. This excludes Lifeboats, which are covered by TC 8.

    The primary ISO TC 88 standard relating to DC shipboard wiring is:

    ISO10133 - small craft (<24metres) extra-low voltage DC(<50volts) explosion & fire protection. Current revision level is 2000(E)

    This standard incorporates normative references the following standards:

    ISO 6722-3: 1993, Road vehicles — Unscreened low-tension cables — Part 3: Conductor sizes and dimensions for thick-wall insulated cables.
    ISO 6722-4: 1993, Road vehicles — Unscreened low-tension cables — Part 4: Conductor sizes and dimensions for thin-wall insulated cables.
    ISO 8846:1990, Small craft — Electrical devices — Protection against ignition of surrounding flammable gases.
    ISO 8846:1990, Small craft — Electrical devices — Protection against ignition of surrounding flammable gases.
    ISO 10239:—1, Small craft — Liquefied petroleum gas (LPG) systems. Italic text(Not yet published when ISO 10133 - 2000(E) was published)Italic text
    ISO 10240:1995, Small craft — Owner’s manual.
    ISO 13297:2000, Small craft — Electrical systems — Alternating current installations.
    IEC 60529:1989, Degrees of protection provided by enclosures (IP Code).
    IEC 60947-7-1:1989, Low-voltage switchgear and controlgear — Part 7: Ancillary equipment — Section One:Terminal blocks for copper conductors.
    Copies (PDF files or hardcopy) can be purchased from ANSI or ISO.

    Rechargeable Storage Batteries
    NOTE: This is a separate category, partly because storage batteries are both Power Sources and Power Loads (when being recharged).

    Boat Battery Basics: Boats and Yachts Maintenance and Troubleshooting http://www.yachtsurvey.com/boat_battery_basics.htm is a very good discussion of storage batteries on boats, thanks to Dave Pascoe.

    Technical resources for design engineers using batteries, chargers and power supplies including wire size and conversions. http://www.powerstream.com/tech.html has a wide range of technical information about various battery types, charging, discharge rates and other technical data.

    Onboard Power Sources
    These are all sources of electrical power that can be used to operate onboard equipment or recharge batteries.

    Propulsion-Engine-driven power sources
    These are DC or AC 'generators' that are powered by the boat's propulsion engine when it is running.

    Standalone Generator systems
    These are systems that combine a separate internal-combustion engine and generator for the specific purpose of generating electrical power.

    Example Generator Systems
    link OSSA Powerlite NOTE: This unit not only supplies onboard electrical power but also powers electric propulsion motors.

    Windpower Systems
    NOTE: Some of the Underway Water / Wake Power Systems below are convertible to Wind Power at anchor.

    Underway Water / Wake Power Systems
    Yes, here's a couple of links: (More info to go!)#TODO#

    http://www.ampair.com/ampair/waterpower.asp "Aquair towed turbine for use in yachts which is the ideal power source for deep ocean cruising yachts. The Aquair towed turbine is strictly speaking a hybrid unit as it can be rapidly converted from “water mode” into “wind mode” as a a wind generator."

    Micro Wind Turbines manufactured by Eclectic Energy Ltd http://www.duogen.co.uk Another dual Wind-Water unit: "DuoGen in water mode produces a steady 8 amps at 6 knots, 11 amps at 7 knots, 16 amps at 8 knots."

    Photovoltaic Panels

    A photovoltaic panel, generally just called "solar cells", is a solid-state device capable of creating an electric current from sunlight. A solar cell is little more than a very large diode, constructed in such a way as to generate electricity in response to light.

    Most commercially available solar cells are based on silicon. More powerful, but also more expensive, are multilayer cells based on gallium arsenide. A typical cell you might buy for a sailboat will convert between 10 and 15 percent of the light that hits it into electric energy; more modern silicon cells can be as much as 22% efficient while a top-quality gallium arsenide cell can capture up to 30% of the sunlight (the downside being such a cell is up to twenty times more expensive than a typical silicon one). On a good sunny day, the light at sea level carries about 1000 watts per square metre of power; thus a one-square-metre panel of 15% cells will max out around 150 watts.

    Silicon cells can only output around 0.7 V or so. Roughly twenty cells (give or take a few) will be wired in series on a panel meant to charge the battery of a 12 V system. The cells must be encapsulated in plastic or glass to protect them from the environment. It is the quality of the encapsulation that determines how long the cell will last (in perfect conditions, they can theoretically last for decades, if not centuries). As an auxiliary power source on a boat, they should be well secured, and the encapsulating material should be perfectly sealed to protect the cells from water, salt and impact.

    Cells work best when pointed directly at the sun; a pivoting mount is ideal on a boat. They will continue to provide power, albeit less of it, in overcast or cloudy conditions. The cells are not conductive if they are shaded; block the light to one cell and the entire bank will shut off. All cells in one series-wired bank should be kept at roughly the same lighting level. If multiple banks of cells are wired to the same battery, but are in different light, maximum-power-point trackers should be used to match the output voltages for best efficiency.

    Using solar as an auxiliary charger is simple and common. Using it as a prime power source is much more difficult, involving high DC voltages and huge cell areas, and is beyond the scope of this article.

    Dockside Power
    Dockside powered battery chargers
    Dockside AC power


    Onboard Power Usage
    Onboard Lighting Systems
    Powering Onboard Systems
    Engine Starting Requirements

    Power Distribution and Protective Devices

    Fuses
    Circuit Breakers

    "Fusible Links"
    Why use a "Fusible Link" rather than a "Fuse" ?? Automobile manufacturers started doing this because high-current fuses used in earlier cars suffered from poor connections and failed from overheating.

    Regular fuses "plug in" and are dependent on a spring pressure for a good connection. Over time, temperature cycles, vibration and environmental contamination, the contact between the fuse and its holder gets worse and worse and the contact resistance goes up. That causes heat, which makes contact/corrosion worse. An overheated fuse blows before its normal current rating. Replacing the fuse in a corroded holder doesn't last long. I've seen "3AG" type fuseholders on older boats that were green with corrosion.

    "Fusible Links" solve this problem two ways:

    1. The connection is made with a good crimp connector that makes a high-pressure large-area gas-tight connection

    2. The joint is covered with a water-tight shrink covering. The newer ones have a remelted zone over the wires.

    In an automotive or Marine environment this is a much more reliable years-long-life solution. Some Boats have a large (100 to 200 amp) 'fuse' near the battery that feeds a main cable to the main circuit breaker panel. Good fuses have large LUGS that bolt to lugs on the cable, with lots of pressure and area. They do not rely on spring pressure in a fuse holder. I hear they are reliable.

    Shipboard Wiring
    Size and Type of wire and cable for shipboard wiring
    ABYC AC/DC Electrical Systems on Boats (Under Committee Review) Adobe PDF

    Editgrid.com http://www.editgrid.com/user/boatdesign/BoatWireSizing (An online spreadsheet for calculating needed wire sizes.) You enter wire length and operating current. (Remember to count both outgoing and returning wire length). After you enter a value and hit <enter> the table of values will update and show you the voltage drop for all the different wire sizes, and whether a wire size is safe, based on maximum current ratings.

    Mechanical considerations in Shipboard Wiring
    Marine Wiring Color Codes
    Brown with Yellow or White tracer Bilge pump automatic switch
    ES-MarineWireColorCode.jpg

    Electrical Connectors for Shipboard Applications

    Electrical connectors on shipboard have more demanding requirements than those for shore applications. In particular, protection from corrosion and resistance to uncoupling under shock and vibration are important.
    1. TODO# Discussion and images of of typical AC and DC power connectors, suggested connectors for new construction, etc.
    Typical Shipboard wiring practices
    Troubleshooting and Tips on Onboard Wiring Problems

    Maintenance and Troubleshooting : Tips on Electrical System Use and http://www.yachtsurvey.com/ElectricalSystems.htm Tips on Electrical System Use and Maintenance - by David Pascoe
    Example Wiring Diagrams and Physical Layouts
    NOTE: The US Coast Guard example "Wiring Diagrams" below are physical layout examples, and show categories of devices and the corresponding rules sections. They are NOT "Schematic Diagrams" and do not show individual actual connections. They are not adequate to define the actual detailed wiring of a boat.

    The following image is a small section example only, from the US Coast Guard manual.

    WiringLayout-AuxSailboat-xpt.jpg

    Here are pointers to larger diagrams:
    Human Interfaces and considerations
    Power Budgeting for cruising boats

    REFERENCES

    The Mother of All Maritime Links: Page 18 of 47 http://www.boat-links.com/linklists/boatlink-18.html

    Basic Electricity Boat Building Standards | Basic Electricity | Direct Current http://newboatbuilders.com/pages/electricity1.html

    Note: this is an archived page from the Boat Design Wiki project which was active from 2007 through 2010 and archived in 2017.
     

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    Last edited by a moderator: May 3, 2017
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