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Old 16-01-2011, 03:48   #1
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Three-Phase 12vdc Wind Generator Wiring Earth ( Ground )

I installed a small 150 watt 12 volt 3 phase wind generator some time ago on my Hunter 310 using the rear stainless steel rails, 2 meter mast and some clamps. It has a slip ring and three wires, which are the three phase electrical outputs.

I have a 3 core cable running to my 3 phase rectifier and controller and batteries which seems to work okay, but given fickle winds, never got too much power out of it, at best 1-2 amps. Each phase shows around 9 volts AC when its spinnings.

A few days ago, whilst stepping on the board in a fair wind, I got electric shock (eg touching the rail and wet feet)

I check the rail and found it was isolated and not earthed/grounded.

I pulled the wind generator / mast off the boat, checked the inside wiring and did an electric drill test, which showed 6 amps being generated.

I also tested resistance to the generator case / mast, which showed around 0.6 ohms on each phase, suggesting the stator wiring is connected to the case.

After remounting it on the boat, I attached an earth wire to the rail to ground it, but the wind generator slowed right down. Removing the earth it spun around "normally"

The question I have is for 3 phase wind generators, should the mast/ case be grounded / earthed or left isolated for it to work properly.

My guess is that it should be grounded / earthed (eg where else would it suck the electrons from), but this does not explain why the wind generator slowed right down when earthed.

Any suggestions / help would be appreciated.

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Old 16-01-2011, 04:44   #2
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if you getting shocked, then a process of elimination, until the voltage is no longer present on the rail will tell you the faulty wiring!!! to me it sounds like you have (+) voltage going to ground . so when you connect the bond its like turning the brake switch on, which stops the genny.

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Old 16-01-2011, 11:16   #3
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Imho, the case shouldn't be connected to any part of the windings, and the case should be grounded.
I suspect a short inside the unit to the case.
Maybe a missing/damaged insulating washer on a brush holder??

Steve B.
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Old 16-01-2011, 21:43   #4

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three phase DC voltage? Am i missing something? phases are for Alternating current...

but, if it is an AC generator then no, the nuetral leg, what some might call ground, should not be connected to the ships ground, or EARTH... that same nuetral/ground shouldnt be connected to the housing of the generator. and you should isolate the metal from teh generator housing from the railing, and see if that stops the problem... but maybe you can put some neoprene or insulation between the mounting hardware and the railings...

I will do some research and see what a 12vAC generator is all about...
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Old 16-01-2011, 21:53   #5

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ok, did some research and then re read your post... yes, generators produce AC, and use a rectifier to convert it into direct current...

your wires should not be grounded to the boat in anyway... the housing should not be grounded to any of the wires... perform a continuity test to see if you are shorting out any of those leads to the housing/casing...

if there isnt a short then you can connect the housing to a 'common ground' I think... but you need to check the inverter documents and radio and other transmitter to confirm...

is your boat on shore power when you are climbing on board? which is why you dont want to share grounds/nuetral on a generator or inverter with shore power...
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Old 17-01-2011, 08:37   #6
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The output of the generator cannot avoid being grounded because it becomes common to the battery's negative/grounded conductor. The external metal on the generator should be grounded or there is a possibility of it "floating" to a static potential or exposing someone to a shock.

If you ground the external case and the generator's armature slows/stops, it indicates an internal short on the stator. Some things that could be the cause include a bare spot in the wire insulation (looks like varnish) that is touching exposed metal. Although it could be a shorted turn in the wiring itself but I doubt it. It could even be a short on the rectifiers, no--- not a shorted rectifier but the wiring to a rectifier. SeniorMechanic's above post is right on topic..... as he mentions a possible short on one of the brushes or slip rings. If the short is there, I would look at the case to the + connection to brush/slip ring.

If it was my genny, I would take it apart and see if I could find the short. Good luck--

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Old 18-01-2011, 04:28   #7
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Thanks for the advice - another dismast and pull apart job I guess

Still can't work out why on the drill test it pumped out 6 amps but won't do it on the boat

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Old 13-02-2011, 02:05   #8
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Pulled it apart again and removed the slip ring.

Seems one of the bolts has cut thru some of the wires.

I had read somewhere that since a boat moves with the winds on swing mooring, a slip ring was a bit useless anyway. I guess time will tell if the cable twists up.

Worths a treat now and no shocks on boarding.

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Old 13-02-2011, 04:26   #9
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Cable will twist up eventually, albeit slowly. Many folks building amateur wind gnerators omit slip rings and add a plug at the end of the cable. Then it is just a matter of periodic maintenance to disconnect the plug and untwist the cable.

I am with senormechanico (#3) in that the case sholud be grounded (and mast too). This will protect you from shocks, should another short to case occur. In wet and salty environment this is even more important than on land.

For reference I recommend these links links:
3 phase basics: 3 Phase Basics
and Wikipedia has some more theoretical approach to the sublect: Y-
Three-phase - Wikipedia, the free encyclopedia

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Old 13-11-2013, 11:07   #10
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Re: Three-Phase 12vdc Wind Generator Wiring Earth ( Ground )

Hi. Just mentioning I have been having the same problem. Exactly. When I removed the earth cable that I had placed on my anode, the turbine started working but I was getting a shock from the frame. Small price to pay I thought since my batteries were getting charged…
Unfortunately, 4 months later, 2 o'clock in the AM in a F5 off shore Portugal, I saw some sparks coming off the frame shortly before I lost all electricity on board… The steel handle from my bucket had come in contact with it. 6 hours of hand steering by the stars later, I have now grounded the pole by trailing a cable into the water from it, but I'm wondering if this is the right solution? Anyone?

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