Re: [Amel Yacht Owners] Re: Prop Shaft Electrolysis
toggle quoted messageShow quoted text
I have to get to Colombia and check the transfer switch, generator, and the Calpeda pump.
I will then have an Idea as to what Amel did.
In Ny now.
From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: Thursday, December 03, 2015 10:37 PM
Subject: Re: [Amel Yacht Owners] Re: Prop Shaft Electrolysis
Where is the AC ground wire connected at the generator, Eric?
I spoke to an ONAN service guy who says that the 220AC output cable has to be connected to the housing on the generator (the box just to the port side of the bigger box with the breakers and stop switch).
He said the only way to isolate the 220AC ground from the bonding system is to remove the bonding cable from the generator. There is a small pencil zinc in the heat exchanger that he says is enough to protect the generator.
So, is your generator connected to the bonding system?
Thanks for your thoughts Jamie. It's going to take me a while to digest that.
My brain hurts.
My generator has an isolated ground and the negative is not connected to the start battery except when the generator is starting.
Kimberlite Amel Super Maramu #376
Kent, again thanks for the kind words about my engine failure on Phantom. Just to confirm my comments, I am not suggesting the exhaust design was necessarily at fault, but in my case the layout of the system certainly could have exacerbated my engine failure. In any event, if I can take steps to improve with my new engine, I will.
If I can comment on your AC findings, I understand that Amel deliberately does not connect the AC earth to the DC bonding grid. That, of course, is totally opposite from US regulations that mandate that connection for safety, a practice to which I fully subscribe as an electrical engineer. There is also the absolute "no-no" of connecting AC neutral to earth anywhere on the boat unless you have an isolation transformer.
The exception, however, is at a separately-derived power source. For a shore power connection, the neutral-to-earth bond would be at the shore power source in the marina. For a generator, it would be at the generator. When the automatic transfer switch (ATS) is in shore power mode, it ensures the neutral is connected only to the shore power feeder and not the boat. It also ensures the grounding systems are not interconnected, since the neutral is not connected to the boat systems. Further the generator case will be connected to earth, since the battery negative for the starter lands on the frame. When the ATS is switched to generator, the neutral "should" be tied to AC earth, since it "should" be bonded to PE at the generator. You should verify the connection between the blue neutral wire and the green/yellow PE. If it is connected you are safe; if not, and you had a fault in an AC circuit to earth, the neutral would not have a return path to its source and the AC current would try to find an alternate path - not good.
Many don't I know, but technically an inverter is a separately-derived power source, and the neutral there should be tied to earth as well. The problem is that most inverters also function in pass-through mode.
I hope that helps. Let me know what you find.
s/v Phantom Amel 54
Well, I have separated all the 220AC ground wires at the 220 box in the galley and at the 220 boxes in the engine room. I found that the output cable from the generator is grounded to the generator case, and thus, to the bonding system. The other end of that cable goes to the automatic switch that chooses generator over shore power, where it is connected to all other 220 grounds via the output from the switch.