Tuesday, February 27, 2018

Re: [Electric Boats] Re: Electric motor Grounding locations

 

For 48 volts and less,  I follow the ABYC E-11 recommendations and have a common ground between all systems.  At higher voltages ABYC TE-30 says keep them separate.  

I personally went with a 48 volt system because I wanted to be able to have a common ground. I don't like having different potentials between different systems that I or a swimmer nearby could be a bridge path between.

More important then if you bridge the two DC grounds together, make sure your old AC system still has earth ground. Most marine systems used the engine block via the shaft to ground to earth.  If your boat does not have another path, once you removed the old engine your entire ground system may be isolated from earth.  

If so a cheap 35 dollar shaft brush will re-earth your system.  See my earth ground bellow:




On Feb 27, 2018, at 10:10 AM, king_of_neworleans <no_reply@yahoogroups.com> wrote:

 

My 48v system is not grounded. General consensus seems to be that this is best. As for grounding the controller, I think tech support at Sevcon can provide a better answer on whether it should be grounded or not. My Kelly controller is not grounded. My motor casing and rotor shaft are incidentally grounded, of course. However phase windings, power supply cables and 48v bank are all floating. Some owners also use a flex coupling to isolate the motor shaft and casing from ground as well, though I don't think it is necessary.



---In electricboats@yahoogroups.com, <mattkaine@...> wrote :

So I just installed a 10kw motor Kit from Trunderstruck EV on my 1976 Islander I-28. I am very happy with the install, works awesome. I am however not sure on best method for grounding new power system. So the current set up is this...I have 2x 12v house batteries with a common ground bus, my 120vAC shore power connects its ground to same ground bus. Now where I am not sure...the 48v motor system consists of 8x 6vDC batteries in series>Power relay>Sevcon Gen4 Controller>motor. Ground bypasses the relay and goes straight to Sevcon. Should I connect 48v bank  to 12v ground bus? Should I run a separate ground from motor frame to ground bus?

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