Re: [Amel Yacht Owners] Alternator and Masse leak detector


ngtnewington Newington
 

Hi Bill,

As I understand it, the Isolated ground system on an Amel is no different to other yachts with Isolated ground systems, and is quite simple namely that the negative of the DC system (and indeed the AC system) is not connected to the rest of the equipment in the boat. So every piece of 24v equipment is connected to the battery bank with a +ve and negative wire via the switch panel and or busbars or indeed directly to the batteries. The battery bank negative is not connected to the engine block or anodes. Then all the equipment and metal on the boat is linked together and earthed to the sea independent of the battery bank.

With this system the alternator for example has to be an isolated ground alternator. That is the -ve terminal is not electrically connected to the alternator frame as on some alternators. So there are two terminals on the back of the alternator, one +ve and one -ve and there is no electrical contact between them and the alternator frame.

If the +ve or the -ve on the battery system is connected to the ground system a fault light appears on the “Masse” detector.

If any sensor or piece of equipment on the engine is not isolated ground rated then its -ve will make an electrical contact with the bonding system.

It is, to my eye, likely that the 24v charging alternator has a fault such that the negative terminal is leaking to the frame of the alternator and thus to the engine itself which is connected to the bonded system and to the sea. By disconnecting the 24v negative cable from the faulty alternator there is no longer a contact between negative 24v and the bonding system, which is why the fault light goes off then.  Thus we have found the fault.

Furthermore I suspect that within the faulty 24v alternator we will discover that it is one of the diodes within the rectifier that is leaking to the frame, but that remains to be seen.

Kind regards

Nick

On 19 Jun 2018, at 19:20, Bill Rouse brouse@... [amelyachtowners] <amelyachtowners@...> wrote:


Nick,

I am sending you an Off-Group, direct email.

Best,

CW Bill Rouse
Admiral, Texas Navy
Commander Emeritus
Amel School  http://www.amelschool.com
720 Winnie St
Galveston Island, TX 77550
+1(832) 380-4970






On Tue, Jun 19, 2018 at 1:00 PM Nick Newington ngtnewington@... [amelyachtowners] <amelyachtowners@...> wrote:
 

Hi Bill,


I am the second owner.

The engine is original. I purchased the boat in June 2017,  it had been ashore in Grenada for three years as the then owner was very ill and unable to use the boat.

The only thing that was changed on the engine in my ownership has been the turbo boost pressure sensor. This was a five minute job to remove the old sensor and replace with new sensor. Done by Volvo agent in Martinique.

In the year I have owned the boat I have had no zinc sacrifice beyond normal, there was until recently no fault on the indicator including just after the turbo boost  sensor was replaced. So this fault is new.

I already have a propeller zinc.

Is there a way in which I can test if the Isolated ground has been defeated?

Nick
On 19 Jun 2018, at 16:07, Bill Rouse brouse@...[amelyachtowners] <amelyachtowners@...> wrote:


Nick,

Your problem may be an indication of something much more serious.

How long have you owned this Amel 54? Has there been an engine change, or any sensors changed?

When Amel installed the Volvo D3-110, it had been modified to be Isolated Ground by Volvo France. If you ask any Volvo dealer to check the serial number for such a modification, it will not show up on Volvos database. In fact, it is difficult to find any Volvo record of this modification which occurred with 100% of all D3s installed when the 54 was built by Amel. 

I believe that your Isolated Ground has been defeated because of either:
  1. Engine change
  2. Non-Isolated Ground sensors or switches installed replacing original ones
  3. Some other modification made by some "expert" which has defeated the Non-Isolated Ground
Yes, if any of the above are true, when you disconnect the 24VDC Negative from the 24VDC Alternator, you will remove the fault indicated on the Bonding test circuit..

I consider this issue serious and you should seek expert help.. A defeated Isolated Ground has been the cause of ruined C-Drives and other serious issues. Until you have this resolved, you should add a propeller zinc, although that will not completely protect things.

Best,

CW Bill Rouse
Admiral, Texas Navy
Commander Emeritus
Amel School  http://www.amelschool.com
720 Winnie St
Galveston Island, TX 77550
+1(832) 380-4970






On Tue, Jun 19, 2018 at 5:23 AM Nick Newington ngtnewington@... [amelyachtowners] <amelyachtowners@...> wrote:
 

Hi Alan,


I have had an electrician check the boat for me and I asked him to look into the -ve leak and to then try some diagnosis..

This is his reply  "I checked the leak controller, it shows a leak in negativ. I tried several things like bilge pump but nothing changed. When I dismantled the negativ from the 24 V alternator, the leak light went off. So, the problem might be the alternator or somewhere at the engine.”

So I reckon that this would suggest a fault on the 24v alternator or some kind of leak to the bonding system from the engine.

Nick


On 19 Jun 2018, at 02:18, divanz620@... [amelyachtowners] <amelyachtowners@...> wrote:

Hi Nick,


We have a NEXT STEP-2 reg ...there is a file in the Files section showing how I did it

The reg in the Leece  Neville alt is not designed to charge deep cycle batteries.
Keeping the voltage always at 28.8V will eventually kill your AGM batteries. They need a bulk, absorption, float regimen if they are to be cared for properly.

We have 
600W solar panels and  a Victron MPPT controller
Leece Neville 175A engine alt with Next Step-2 reg
Victron Skyalla 100A charger
Promariner 30A charger

and they are all set to the same absorption and float voltages.


Diodes fail open, I don't think that can be the cause of your problem.

Somewhere on some device that has both 24VDC feed AND a connection to the bonding system, there is a connection between -ve and the bonding connection...and it may not be a metal to metal contact , frequently it is through the sea water. 

Good Luck
Alan
Elyse SM437  Yasawa-i-rara









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