Galvanic isolator DIY

[rwidman]

A couple of Bridge rectifiers at about $5.00 each and a hunk of aluminum angle and some wire about a $20.00 investment vs a couple of hundred for a factory one.

It does exctly the same thing.

Not looking for permission here. It is just me. I like to know how things work and why.

Great idea Av8r of a light on the unit (constant on) just to tell me the thing is doing what it is supposed to do is a great idea.
I will install it this weekend.

Such a simple thing.

Sd

Why are you giving me a hard time? I'm the one who took your side saying that you could build it and it wouldn't void your insurance.

Building or buying a product doesn't make one a better or worse person.

Let me ask you this: Do you know how to cook? Do you sometimes just go out to a restaurant and pay someone else to cook a meal for you?

Same thing, isn't it?

 

[rwidman]

Now you're talking Troll old boy!

Two common doorbell transformers connected back to back (connect the 24volt terminals together) will make an isolation transformer. Now all you need to do is parallel enough ot them to handle the 30 or 50 amps you need for your boat.

 

[boatpoker]

I believe that Anne-Marie (Yandina) is a retired electronics engineer from Australia.

She has been quite prevalent in on line forums and e-mail groups for a long time. She has some interesting and strong opinions about the ABYC.

and yet she still does not know what "electrolysis" is.

 

[BILL GOOD1]

OK Old but "current" for me! AC-Filter Film Cap MPAPM3A0200J0. Life 60000 hrs sounds better than diodes. Prob as good as an isolation transformer & lighter than all other items available. $60 here


Regards Bill

 

[gsholz]

Yes, a cap will block DC but will it handle 30 or 50A short to ground?

 

[kchace]

OK Old but "current" for me! AC-Filter Film Cap MPAPM3A0200J0. Life 60000 hrs sounds better than diodes. Prob as good as an isolation transformer & lighter than all other items available. $60 here


Regards Bill

Since its a cap, it will never pass DC at any voltage (up to its breakdown voltage) and certainly won't allow the passage of 30 or 50 amps AC which a good ground requires. Putting a part like that in line will cause you to have no safety ground.


Ken

 

[BILL GOOD1]

How long do you want to pass 30 or 50 amps for before a safety switch or fuse operates in a fault situation? Do you really need to pass such high continuous current.

200uf for 110V ac 60hz will be 13 ohm for 11 amp & that is 1.6kw. 240v ac 50 hz 16 ohm 19 amp for 6kw (cal peak RMS). Maybe a larger cap. for a lower Z. This one this seems a easy solution. Still investing & asking questions. Remember the DC resistance of seawater is higher than ground & the higher Z of the caps is taken into the cals. Seawater ops not fresh.

I don't believe diodes would last in some units for long enough to operate safety circuits under fault conditions passing 30 or 50 A. with units offered for sale at 15 or so amps.

Bill (still trying to workout how electrons in the Galvanic process can pass from an anode which is neg to a pos cathode under my boat.)

 

[gsholz]

You want high current to trip the breakers during a fault to ground. With your approach you have high impedance in the ground wire. There should be none. Your breakers will not trip on a ground fault causing a potential electrocution hazard.

 

[CharlieJ]

@BILL_GOOD1 #31

This is a very bad and potentially dangerous idea.

The safety ground wire in the USA is the "holy grail" for fault clearance. A galvanic isolator is inserted in this fault clearance path and must be robust enough to be able to pass full fault current in order to clear the fault by opening a circuit breaker. Maintaining this fault clearance path is paramount. Note that surges on the shore side electrical system or near hits from lightning strikes can destroy components without sufficient ampacity rating.

The ABYC Standard for Galvanic Isolators (ABYC A-28) emphasizes, through a very stringent third-party testing sequence, the survivability and current carrying capability of compliant galvanic isolators. Exceptionally good electrical component manufacturers have invested a substantial number of R&D dollars in developing a galvanic isolator that has a high probability of surviving a surge and maintaining the fault clearance path back to the source of power.

A talented DIY'er is not going to duplicate this effort with $60 worth of components and a block of aluminum and it will not come close to the protection provided by an isolation transformer.

 

[johnmacd]

I need help !!! , I just bought a 2003 Mainship Pilot 30. It has a Pro Mariner Pro Safe Galvanic Isolation Monitor. When along side with the 30 amp 125v ac shore power connected, and the main battery bank switch is "ON" If I switch on the 12v dc main ( top switch on the circuit panel ) , the galvanic isolator panel alarms... the ground wire indicator says "Normal" the galvanic isolator says "fail" and sounds the beep alarm. If I shut off the 12vdc main which is the top dc switch on the circuit panel the beep goes away. However all the dc circuits still work or are hot with the DC main shut off.
Two things I cannot figure out, why are the dc circuits hot when the " DC main" on the circuit panel is Off.

Secondly I have looked and looked and cannot find the Galvanic Isolator device or connection on the boat, I just see the control panel but don't know where the device is on a Mainship 30?? It looks like a manufacturers installed device

Any light you can shed would be apprenticed, not sure what is going on or what to or what to look for.
Thank you in advance.

 

[gsholz]

Look for wiring changes made by the previous owner(s). Anything that does not look factory.

The galvanic isolator is usually close to the shore power inlet. If your shore power inlet is more than a few feet from the main panel, there should be another set of breakers close to the inlet. That would be a logical place for the isolator.

 

[CharlieJ]

gsholz #41: +1

Also look for a grey control box about 6" X 8" that runs the GI monitoring system.

Note that if you plug into shore power at a marina that has upgraded its pedestals to mee the new NEC, that the testing function of the galvanic isolator will trip the ELCI at the pedestal. Recommend remove the GI and its monitoring system (once you find it ) and install a Dairyland Electric Industries https://www.dairyland.com/galvanic-isolators/ fail-safe galvanic isolator. It is expensive but it is robust and the best on the market in my opinion.

 

[rgano]

Firstly, you have an obsolete galvanic isolator which ProMariner recommends replacing. It seems that indicator panel thingy is the problem, and the new unit has none. I found out my original GI was installed somewhere behind the paneling of the galley area near the reefer and elected to just cut the green wire at the buss bar behind the power panel and install the new one right there behind the stereo.

If you are not connected to shore power, and your master batt switch is on and the DC power breaker at the top of the panel is off, do you still have DC power to the other DC circuits. I am not talking here about the lights on the panel but rather the actual unit. For instance, does the freshwater pump light come on AND does the pump energize when you open the spigot? If so, there is a connection error behind the panel. When I completely modified the battery system in my 30PII to include a house bank, I found three DC power posts behind the power panel. If you will get your volt meter out and play around with the master switch and the breakers down at it, you will discover which post that switch powers and if there is power to one or more of them with the master switch off - not good unless there is a big fuse down there at the battery.

Anyway, the wire from the top DC panel breaker should go to one of those power posts, and no other wires should go from either that post or the other two to any other breaker below the top one on your panel. Now there may well be direct power from a power post to the three bilge pump switches a few inches to the right, just not to the stuff on the far left of the panel.

Here's how the DC distribution looks on Frolic today.