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Inverter for 240VAC system

Discussion in 'Electronics' started by TahoeJohn, May 4, 2021.

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  1. TahoeJohn

    TahoeJohn Member

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    My boat was built in 2001 with an inverter, but it was previously removed (not sure why). I'd like to install a new one.

    The boat is 240VAC/60 Hz, and the 120V loads are roughly divided across both legs. Because of this, I initially assumed that I would need a dual 120V / 240V inverter, but since I'm not finding many options for that, I'm now questioning that assumption.

    For example, Magnum makes a dual 120V output unit, MS4024PAE:
    magnum non-marine.jpg

    However, I don't believe it's marine-rated (no bonding of N and G), as is their single 120V, MS4024, below -- it adds that relay in the center to do the bonding when in inverter mode. This one is also listed under their marine section, while the PAE model is not.
    magnum marine inverter.jpg

    What is the standard approach for powering both 120V legs while meeting ABYC standards? Parallel two 120V inverters?

    Thanks!
  2. Capt Ralph

    Capt Ralph Senior Member

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  3. TahoeJohn

    TahoeJohn Member

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  4. Capt Ralph

    Capt Ralph Senior Member

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    I do not tie the white and green wires at the inverter.
    Our boats shore power transfer switches to that.
    When on the dock, all is separate and fault current (green wire) goes to the dock to be joined with neutral (white wire) per code.
    If the dock has a power failure, the inverter (UPS) comes on and if any fault current happens, passes to the shore tie per plan.

    When we leave the dock, we switch to the gen-sets.
    Here, the white and green are tied on board and any fault current goes to the water.
    Without the gen-sets running, Green and white are already tied for the inverter.

    BTW, I remember on this Magnum, White is not switched and passes thru.
    Last edited: May 4, 2021
  5. Pascal

    Pascal Senior Member

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    I m pretty sure that marine inverters must have a relay bonding N and G when in inverter mode. The Magnums i have used before did. I believe it s an ABYC requirement.

    now, yes I shore power goes down and inverter kicks in, they will be bonded as long as the shore power is physically connected. Same if on generator but only as long as the rotary switch is left in generator position otherwise the N will be disconnected
  6. Capt J

    Capt J Senior Member

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    Be very careful with the shorepower going down and inverter coming on by itself, if the yacht is un-attended. Also make sure you have a charger to charge the inverter bank in case it goes below 21 volts......inverter will not power on and will not charge it's bank(s). I've managed several yachts where everything went through an inverter, (no bypass) shorepower went down, inverter drained all batteries, inverter wouldn't come on due to batteries being too low, and no way to charge the batteries to get the inverter on.
  7. Pascal

    Pascal Senior Member

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    All it takes is adjust the low voltage cutout so batteries don’t drop below a set voltage. That’s who I always want my inverter to be powered by a battery bank so that the DC loads still run especially bilge pumps.
  8. TahoeJohn

    TahoeJohn Member

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    Thank you all - very helpful. One additional thing: This boat's power selection switches have 5 inputs: SHORE1, SHORE2, GEN1, GEN2, and INVERTER. It sounds like I need to determine what, if anything, these switches do with both Neutral and Ground when switched to INVERTER mode.
  9. Capt Ralph

    Capt Ralph Senior Member

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    Yes, Sounds like a good starting point before selecting any equipment.
    Also, If the same transfer switch is selecting between shore and gen sets AND IF PROPERLY STRAPPED, then hopefully the inverter would be strapped white to green or easily adaptable.
    Sadly, I have serviced to many boats where green/white where strapped incorrectly when moving from shore to gen-set.
    Seems like a good time to get in vibe with your boat. Have fun checking out under her skirts...

    If you get that Magnum PAE, it is a great unit. Designed for off-grid, it is a work horse. Done VERY well for us.
    Also, the Magnum support folk are great. just a lil slow in getting with you at first, but when the support starts, their on it.
    TahoeJohn likes this.
  10. Francis Mele

    Francis Mele New Member

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    Can a Relay go bad and cause breakers to shut off.
  11. Capt Ralph

    Capt Ralph Senior Member

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    Well anything is possible. Can you offer any details on your issue?
  12. Francis Mele

    Francis Mele New Member

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    Thank you for trying to help when I plug in sometimes the power stays on but only for awhile. my Plugs thru out the boat have there own gfi some work and some don't get any power at all . then this weekend on generator everything workd all day. when i got back and pugged in to shore power the breaker for the plugs tripped and I started up the generator again and the plugs didn't work.It seems it moves around to different breakers. I only leave on the battery charger Plugs on A/C and it still trips the Relay and Breakers That are connected together I have a my Mechanic and Electronics man working on it But He just keeps trying the stove top ,ice maker and others and says they are no good but i bought this boat couple of months ago and Everything worked just fine . the problem started when i had a air conditioner service man service my air conditioners he told me that the Relay kept tripping and since then other things are tripping.But The Relay and those 3 breakers are now always Tripping

    Thanks Frank Mele

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  13. Capt Ralph

    Capt Ralph Senior Member

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    So what did your AC tec actually do?

    There are a pile of senenaros that can trip GFI breakers (green wire fault current). Regular breakers trip on over current.
    There are wiring rules that must be adheared to when switching between shore and on board service. The inverters either have relays that make these changes automatically or changes through the shore / ship transfer switches. Isolation transformers can ad an extra level of complexity.
    Basic rule 1, white (neutral) and green (ground) wires are separate while configured and using shore or dock power service.
    Basic rule 2, these wires are tied when on the ship's power (gen sets or inverter).

    If the problem really started with the AC tecs work, start there. Lots of great AC guys out there have no clue of the special power considerations on a boat. Bonding ,a whole different bag of worms, is way over their heads also.

    If your party can not find an issue quickly, please find a real marine electrician. Personal saftey may depend on it.
  14. Francis Mele

    Francis Mele New Member

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    Thank You Captain Ralph
  15. Capt J

    Capt J Senior Member

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    Have you considered checking your shorepower cord and everything between the dock and your breaker panel. It's very common for the end on the shorepower cord to go bad or even the cord itself. You need to get a marine electrician out to the boat, not your mechanic and not your electronics guy.
  16. Francis Mele

    Francis Mele New Member

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    Thank You Captain J I will Do This

    Thanks Frank
  17. Pascal

    Pascal Senior Member

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    What kind of boat is this? Judging by the picture you posted I m guessing European. Was it modified for US electrical?
  18. Francis Mele

    Francis Mele New Member

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    Azmuit Atlantis 40 Express 2011
  19. Capt Ralph

    Capt Ralph Senior Member

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    That could explain some of it. :rolleyes::rolleyes::rolleyes: