Isolation Transformer and DC corrosion
Since my post a few days ago, spoke to our marine electrician and the
on-staff electrical expert retained by the Harbor office. We are going to have to install an isolation transformer in our dock box. This will cost about $1,000 after parts, labor and some mods to the box. All 90 boats in our harbor that got the notices have to do this, move, or unplug or disconnect the AC ground from the DC, not a good option. So, now I see the West Advisor says that apparently solves the marina's issue with the AC, but unless we separate all the underwater stuff, like the through hulls, we still are subject to DC corrosion. Can this be true? What is the real solution to the AC, the DC, the safety and the corrosion problem? Is there one? We are one of 90 modest boats from about 28-48 feet, mostly 1970's through 1990's vintage. We all have to get these transformers now, but the issue is what else do we need to do once we are on the transformer? |
Isolation Transformer and DC corrosion
If you have 90 boats in the marina with the same problem then the problem is
with the marina and not the boats. The marina operator is just trying to pawn it off on the boat owners. Trusting what the "electrician" say doesn't cut it because it is very likely that he caused the problem in the first place. I would get everyone together and chip in maybe $50 each and hire a real EE to figure out what the problem is and force the marina operator to fix it. $4K for a couple of days investigation by someone who knows what he is doing is certainly better than covering the marina operator's ass by spending over $100K to cover up the symptoms. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "Russell" wrote in message oups.com... Since my post a few days ago, spoke to our marine electrician and the on-staff electrical expert retained by the Harbor office. We are going to have to install an isolation transformer in our dock box. This will cost about $1,000 after parts, labor and some mods to the box. All 90 boats in our harbor that got the notices have to do this, move, or unplug or disconnect the AC ground from the DC, not a good option. So, now I see the West Advisor says that apparently solves the marina's issue with the AC, but unless we separate all the underwater stuff, like the through hulls, we still are subject to DC corrosion. Can this be true? What is the real solution to the AC, the DC, the safety and the corrosion problem? Is there one? We are one of 90 modest boats from about 28-48 feet, mostly 1970's through 1990's vintage. We all have to get these transformers now, but the issue is what else do we need to do once we are on the transformer? |
Isolation Transformer and DC corrosion
Russell wrote:
Since my post a few days ago, spoke to our marine electrician and the on-staff electrical expert retained by the Harbor office. We are going to have to install an isolation transformer in our dock box. This will cost about $1,000 after parts, labor and some mods to the box. All 90 boats in our harbor that got the notices have to do this, move, or unplug or disconnect the AC ground from the DC, not a good option. So, now I see the West Advisor says that apparently solves the marina's issue with the AC, but unless we separate all the underwater stuff, like the through hulls, we still are subject to DC corrosion. Can this be true? What is the real solution to the AC, the DC, the safety and the corrosion problem? Is there one? We are one of 90 modest boats from about 28-48 feet, mostly 1970's through 1990's vintage. We all have to get these transformers now, but the issue is what else do we need to do once we are on the transformer? Well, the way this has happened concerns me, as I said before. That you are required to purchase the transformer makes the situation even worse (except for whoever is making a $90,000 sale). I know of no precedent for an action of this sort by a marina. It is really too bad, because it is fairly easy for an unskilled technician to determine which boat(s) are causing the problem. Regardless, the transformer will solve the corrosion problem ONLY if the secondary hot and neutral are connected to nothing on land. No grounding on land whatever. You then will use the neutral wire onboard as both neutral and ground. The corrosion problem I'm referring to is one in which an unprotected vessel near yours obtains protection from your zinc using the AC grounding conductor as the return path. There are obviously other corrosion problems, some quite serious, but the isolation transformer will do nothing to protect against those. You will still need a zinc to protect underwater props, etc., but that is almost always under your complete control. Except in very unusual circumstances, if you install proper sized zincs and check them from time to time, you should have no further corrosion problems. A technician can even show you how to make simple measurements to check on whether your protection system is working. To summarize: yes the transformer will completely eliminate what it appears is causing your corrosion problem based on what you have described. I don't believe the isolation transformer will introduce any new problems at all, other than the cost. Hope this helps, Russell. Good luck. Chuck ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Isolation Transformer and DC corrosion
Glenn Ashmore wrote:
If you have 90 boats in the marina with the same problem then the problem is with the marina and not the boats. The marina operator is just trying to pawn it off on the boat owners. Trusting what the "electrician" say doesn't cut it because it is very likely that he caused the problem in the first place. I would get everyone together and chip in maybe $50 each and hire a real EE to figure out what the problem is and force the marina operator to fix it. $4K for a couple of days investigation by someone who knows what he is doing is certainly better than covering the marina operator's ass by spending over $100K to cover up the symptoms. I second Glenn's suggestion! ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Isolation Transformer and DC corrosion
Whatever you do, don't install the isolation transformer at the dock box,
install it in your boat. That way you can easily take it with you. And BTW a 30 amp Charles River isolation transformer is less than $500 bucks and will take less than an hour to install it on your boat. David |
Isolation Transformer and DC corrosion
Definitely mount it on the boat. Once you make a place for it to mount
wiring it up is simple but I wish I could find a Charles transformer for less than $500. I need two and the best price I have found is $670 each. -- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "David&Joan" wrote in message news:VQllg.104732$iU2.45028@fed1read01... Whatever you do, don't install the isolation transformer at the dock box, install it in your boat. That way you can easily take it with you. And BTW a 30 amp Charles River isolation transformer is less than $500 bucks and will take less than an hour to install it on your boat. David |
Isolation Transformer and DC corrosion
"Russell" wrote in news:1150664559.195111.128480
@h76g2000cwa.googlegroups.com: Since my post a few days ago, spoke to our marine electrician and the on-staff electrical expert retained by the Harbor office. We are going to have to install an isolation transformer in our dock box. This will cost about $1,000 after parts, labor and some mods to the box. All 90 boats in our harbor that got the notices have to do this, move, or unplug or disconnect the AC ground from the DC, not a good option. So, now I see the West Advisor says that apparently solves the marina's issue with the AC, but unless we separate all the underwater stuff, like the through hulls, we still are subject to DC corrosion. Can this be true? What is the real solution to the AC, the DC, the safety and the corrosion problem? Is there one? We are one of 90 modest boats from about 28-48 feet, mostly 1970's through 1990's vintage. We all have to get these transformers now, but the issue is what else do we need to do once we are on the transformer? As long as the AC ground on the dock is connected to the DC ground, and therefore all the underwater metal parts of the boat, the electrolysis problems caused by your boat being connected to the earth and all the other boats so connected WILL CONTINUE UNABATED, isolation transformers or no isolation transformers! It's a BATTERY made up of your metal parts, the seawater as electrolyte and the marina metal parts, including the bottom of the harbor the marina is grounded to! You have, by shorting your plate of the battery to the marina plate of the battery, SHORTED OUT THE ELECTROLYSIS BATTERY and its plate is going to be EATEN in the process. AC power is not required to accomplish this, only CHEMISTRY, basic battery chemistry. Now, the secondary winding of the isolation transformer HAS NO GROUND WHATSOEVER, if it is an isolation transformer it isolates its AC power from GROUND. So, you may touch ANY grounded anything, including the AC power ground wire of the power company itself, from EITHER side of the AC output winding of the isolation transformer and you WON'T GET SHOCKED! That's why we call it an ISOLATION transformer....it isolates the AC power going to the boat from GROUND. Once the AC power supply to the boat has no ground connection, whatsoever, you can fully disconnect the boat from shore ground, altogether, and noone will get a shock UNLESS THEY CONNECT THEMSELVES STRAIGHT ACROSS THE TWO OUTPUT WIRES OF THE ISOLATION TRANSFORMER WHERE THE POWER HAPPENS. There are NO other circuits for current to flow through! The only connection from the primary side to the secondary side of an isolation transformer is MAGNETISM IN THE CORE. There are special insulating tapes put between the core of the transformer and the windings to PREVENT any path between them. Geez....this ISN'T ROCKET SCIENCE! Disconnect the damned shore ground from the boat and install the isolation transformer with no secondary ground and it'll be JUST FINE FOR ALL! Once the isolation transformer is between the boat and the power company, the boat only needs TWO WIRES!..the ones to the secondary 120VAC winding! |
Isolation Transformer and DC corrosion
"Glenn Ashmore" wrote in news:tbnlg.112499$Ce1.112216
@dukeread01: Definitely mount it on the boat. Once you make a place for it to mount wiring it up is simple but I wish I could find a Charles transformer for less than $500. I need two and the best price I have found is $670 each. Hmm....50A service at 120VAC = 6 KVA. http://www.charlesindustries.com/main/ma_iso_bost.html 16" x 15" x 12" and weighs 155 lbs....about as much as one passenger. Can't put it in the bilge where it'll rot in the wet, but try to keep it as low as possible and near centerline so you don't lean over too far. Here....justification!: http://www.charlesindustries.com/main/ma_iso_bost.html "The Isolation Transformer The ABYC defines an Isolation Transformer as a transformer installed in the shore power supply circuit on a boat to electrically isolate all AC system conductors, including the AC green grounding conductor on the boat from the AC system conductors of the shore power supply. If we are bringing AC shore power aboard to an electrical panel on a boat, a marine grade Isolation Transformer should always be used in the shore power circuit where it comes aboard, and before it reaches the AC distribution panel or any other device aboard. The AC shore power current passes through the transformer's primary windings only, and induces a current in the secondary windings, which supply the boat. Primary and secondary windings are insulated from each other, and a ground fault on the shore side will not involve our boat. At its simplest form, a transformer consists of two coils of wire in close proximity but electrically isolated from each other, usually wrapped around a common metal core to contain the magnetic fields produced. If an alternating current is applied to one of the coils, it will induce a similar current in the other coil. Most transformers are designed to step voltage up or down by having differing numbers of turns in the two coils. An isolation transformer has the same number of turns in each coil, serving only to isolate the boat from the shoreside power, but to give the same voltage. An Isolation Transformer is used because the shoreside AC power is referenced to ground. If you are connected to the earth and you touch the "hot" lead of a normal shoreside AC service, you will get shocked. The isolation transformer removes the ground reference from the ship's service. Neither of the two sides of an AC circuit on the boat is at ground potential. Therefore you must contact both sides of the onboard supply to shock yourself." |
Isolation Transformer and DC corrosion
Larry wrote: Once the isolation transformer is between the boat and the power company, the boat only needs TWO WIRES!..the ones to the secondary 120VAC winding! The boat still needs 3 wires just like before. One side of the secondary of the isolation transformer will now go to the BOATS ground system, including the green ground wire on the boat. The secondary of the isolation transformer is treated the same way as your generator system when feeding the boat. Regards Gary |
Isolation Transformer and DC corrosion
Russell wrote: Since my post a few days ago, spoke to our marine electrician and the on-staff electrical expert retained by the Harbor office. We are going to have to install an isolation transformer in our dock box. This will cost about $1,000 after parts, labor and some mods to the box. All 90 boats in our harbor that got the notices have to do this, move, or unplug or disconnect the AC ground from the DC, not a good option. So, now I see the West Advisor says that apparently solves the marina's issue with the AC, but unless we separate all the underwater stuff, like the through hulls, we still are subject to DC corrosion. Can this be true? What is the real solution to the AC, the DC, the safety and the corrosion problem? Is there one? We are one of 90 modest boats from about 28-48 feet, mostly 1970's through 1990's vintage. We all have to get these transformers now, but the issue is what else do we need to do once we are on the transformer? You should also be able to install an isolator on your boat, if it does not already have one, and be in compliance of isolating the ground to electrolysis. If an isolator will not function properly in the marina then there is a problem with the marinas wiring, which sounds highly suspect to start with. Ask for the details of how the hired electrician has determined that your boat is causing problems and let us know what he says. What kind of measurements did he do? Regards Gary |
Isolation Transformer and DC corrosion
|
Isolation Transformer and DC corrosion
|
Isolation Transformer and DC corrosion
Larry,
You are correct, but the correct method of connecting an isolation transformer is to use the safety earth at the dock only on the primary side which must be isolated from the hull. Steve "Larry" wrote in message ... "Russell" wrote in news:1150664559.195111.128480 @h76g2000cwa.googlegroups.com: Since my post a few days ago, spoke to our marine electrician and the on-staff electrical expert retained by the Harbor office. We are going to have to install an isolation transformer in our dock box. This will cost about $1,000 after parts, labor and some mods to the box. All 90 boats in our harbor that got the notices have to do this, move, or unplug or disconnect the AC ground from the DC, not a good option. So, now I see the West Advisor says that apparently solves the marina's issue with the AC, but unless we separate all the underwater stuff, like the through hulls, we still are subject to DC corrosion. Can this be true? What is the real solution to the AC, the DC, the safety and the corrosion problem? Is there one? We are one of 90 modest boats from about 28-48 feet, mostly 1970's through 1990's vintage. We all have to get these transformers now, but the issue is what else do we need to do once we are on the transformer? As long as the AC ground on the dock is connected to the DC ground, and therefore all the underwater metal parts of the boat, the electrolysis problems caused by your boat being connected to the earth and all the other boats so connected WILL CONTINUE UNABATED, isolation transformers or no isolation transformers! It's a BATTERY made up of your metal parts, the seawater as electrolyte and the marina metal parts, including the bottom of the harbor the marina is grounded to! You have, by shorting your plate of the battery to the marina plate of the battery, SHORTED OUT THE ELECTROLYSIS BATTERY and its plate is going to be EATEN in the process. AC power is not required to accomplish this, only CHEMISTRY, basic battery chemistry. Now, the secondary winding of the isolation transformer HAS NO GROUND WHATSOEVER, if it is an isolation transformer it isolates its AC power from GROUND. So, you may touch ANY grounded anything, including the AC power ground wire of the power company itself, from EITHER side of the AC output winding of the isolation transformer and you WON'T GET SHOCKED! That's why we call it an ISOLATION transformer....it isolates the AC power going to the boat from GROUND. Once the AC power supply to the boat has no ground connection, whatsoever, you can fully disconnect the boat from shore ground, altogether, and noone will get a shock UNLESS THEY CONNECT THEMSELVES STRAIGHT ACROSS THE TWO OUTPUT WIRES OF THE ISOLATION TRANSFORMER WHERE THE POWER HAPPENS. There are NO other circuits for current to flow through! The only connection from the primary side to the secondary side of an isolation transformer is MAGNETISM IN THE CORE. There are special insulating tapes put between the core of the transformer and the windings to PREVENT any path between them. Geez....this ISN'T ROCKET SCIENCE! Disconnect the damned shore ground from the boat and install the isolation transformer with no secondary ground and it'll be JUST FINE FOR ALL! Once the isolation transformer is between the boat and the power company, the boat only needs TWO WIRES!..the ones to the secondary 120VAC winding! |
Isolation Transformer and DC corrosion
There is another issue that hasn't been addressed by the group. That issue
is in-rush current when connecting an isolation transformer. The problem can be severe if the transformer is correctly sized. I use a transformer that I had custom made for me in Ankara, Turkey. It is 10 KW and it can use shore power from 100V to 280V on either 50 or 60 Hz so it is usable anywhere in the world. The problem is how to keep the in-rush current from popping the service breaker and one answer is a light bulb in series with the primary. Once power has been applied, simply throw a shorting switch bypassing the light bulb before using a load. Steve "Larry" wrote in message ... "Glenn Ashmore" wrote in news:tbnlg.112499$Ce1.112216 @dukeread01: Definitely mount it on the boat. Once you make a place for it to mount wiring it up is simple but I wish I could find a Charles transformer for less than $500. I need two and the best price I have found is $670 each. Hmm....50A service at 120VAC = 6 KVA. http://www.charlesindustries.com/main/ma_iso_bost.html 16" x 15" x 12" and weighs 155 lbs....about as much as one passenger. Can't put it in the bilge where it'll rot in the wet, but try to keep it as low as possible and near centerline so you don't lean over too far. Here....justification!: http://www.charlesindustries.com/main/ma_iso_bost.html "The Isolation Transformer The ABYC defines an Isolation Transformer as a transformer installed in the shore power supply circuit on a boat to electrically isolate all AC system conductors, including the AC green grounding conductor on the boat from the AC system conductors of the shore power supply. If we are bringing AC shore power aboard to an electrical panel on a boat, a marine grade Isolation Transformer should always be used in the shore power circuit where it comes aboard, and before it reaches the AC distribution panel or any other device aboard. The AC shore power current passes through the transformer's primary windings only, and induces a current in the secondary windings, which supply the boat. Primary and secondary windings are insulated from each other, and a ground fault on the shore side will not involve our boat. At its simplest form, a transformer consists of two coils of wire in close proximity but electrically isolated from each other, usually wrapped around a common metal core to contain the magnetic fields produced. If an alternating current is applied to one of the coils, it will induce a similar current in the other coil. Most transformers are designed to step voltage up or down by having differing numbers of turns in the two coils. An isolation transformer has the same number of turns in each coil, serving only to isolate the boat from the shoreside power, but to give the same voltage. An Isolation Transformer is used because the shoreside AC power is referenced to ground. If you are connected to the earth and you touch the "hot" lead of a normal shoreside AC service, you will get shocked. The isolation transformer removes the ground reference from the ship's service. Neither of the two sides of an AC circuit on the boat is at ground potential. Therefore you must contact both sides of the onboard supply to shock yourself." |
Isolation Transformer and DC corrosion
I had a diver under the boat today. This boat was in the yard ten weeks
ago. New shafts, props, all new zincs everywhere (tabs, rudders, shafts, transom, etc.). The diver reports the ZINCS ARE GONE!!! Even most of the bolts are gone or just hanging. How can this be happening? If it is another boat, what can I do to find it or to protect against it without exposing anyone on my boat to AC shock. In the meantime, we are unplugging from shore power, which is scary, although our bilges are pretty dry. I read all the posts, but am still confused on whether it is AC or DC related, and if the isoloation transformer has any impact. Oh, one more thing. We had a new computerized charger installed a while back. I wonder if it were wired incorrectly would that cause the zincs to go like this? Russell wrote: Since my post a few days ago, spoke to our marine electrician and the on-staff electrical expert retained by the Harbor office. We are going to have to install an isolation transformer in our dock box. This will cost about $1,000 after parts, labor and some mods to the box. All 90 boats in our harbor that got the notices have to do this, move, or unplug or disconnect the AC ground from the DC, not a good option. So, now I see the West Advisor says that apparently solves the marina's issue with the AC, but unless we separate all the underwater stuff, like the through hulls, we still are subject to DC corrosion. Can this be true? What is the real solution to the AC, the DC, the safety and the corrosion problem? Is there one? We are one of 90 modest boats from about 28-48 feet, mostly 1970's through 1990's vintage. We all have to get these transformers now, but the issue is what else do we need to do once we are on the transformer? |
Isolation Transformer and DC corrosion
"Steve Lusardi" wrote in
: Larry, You are correct, but the correct method of connecting an isolation transformer is to use the safety earth at the dock only on the primary side which must be isolated from the hull. Steve Correct. The boat must NOT be connected to dock ground to stop the underwater fizzing...(c; |
Isolation Transformer and DC corrosion
"Steve Lusardi" wrote in
: It is 10 KW and it can use shore power from 100V to 280V on either 50 or 60 Hz so it is usable anywhere in the world. The modern way of creating a wide ranging, DC to radio frequency isolation "transformer" isn't a transformer at all...... Whatever input AC voltage and frequency is available over a very wide range is simply "consumed" by a full wave bridge rectifier and low frequency DC filter, the same as the power supply in your desktop computer. The resultant unregulated DC, now from 80 to 400VDC is fed to a high-powered switching inverter, like your battery-powered inverter, that feeds off whatever DC is available from the rectifier-filter. Its output frequency is crystal-controlled, its output sinewave is sampled, measured and the results are fed back to the inverter's control IC, which determines the pulse width of the inverter's high powered, high voltage transistor switching array. Over the range of loads from no load to the capacity of the unit, output is a virtual sinewave at exactly 60 Hz, voltage regulated to be rock steady. Because such electronics uses a high frequency switching system with very lightweight toroid transformers, unlike the old magnetic transformers, you don't need a fork lift to haul them down the dock, even though they will create 10KW or more of stable AC power, completely isolated from the power company and ground. This is exactly how the new inverter gensets, like my Honda EU3000i 3KW work. The "generator" is a very high frequency, permanent magnet, 6 phase alternator built into the flywheel of a 6.5 hp, 1-cyl, computer controlled by the inverter, engine. It looks just like the stator windings on an outboard motor it was copied from. Being very high frequency, in the kilocycle range, the size of the magnetic parts becomes very small and lightweight. The inverter behind the power outlets merely rectifies and filters it into DC to run the modified sine inverter from, instead of rectifing the AC line in the paragraph above. Switchers are very neat, very efficient pieces of electronic art....(c; |
Isolation Transformer and DC corrosion
"Russell" wrote in news:1150917215.062248.50070
@p79g2000cwp.googlegroups.com: I had a diver under the boat today. This boat was in the yard ten weeks ago. New shafts, props, all new zincs everywhere (tabs, rudders, shafts, transom, etc.). The diver reports the ZINCS ARE GONE!!! Even most of the bolts are gone or just hanging. How can this be happening? If it is another boat, what can I do to find it or to protect against it without exposing anyone on my boat to AC shock. In the meantime, we are unplugging from shore power, which is scary, although our bilges are pretty dry. I read all the posts, but am still confused on whether it is AC or DC related, and if the isoloation transformer has any impact. Oh, one more thing. We had a new computerized charger installed a while back. I wonder if it were wired incorrectly would that cause the zincs to go like this? It is DC related because your underwater metal parts are hooked directly to the electrical system on the dock's ground wire. This amounts to running a wire from your engine block and underwater metals to every other boat's underwater metals and the entire bottom of the bay. This results in some horrific electrolysis currents, you zincs trying to provide noble metal to protect the whole marina, not just your skeg and prop, eating it away at an amazing pace. When the zinc was gone, the next least noble metal started to be used as the underwater battery plate in the shorted system. Get a digital multimeter from someone. Unplug the boat at the dock post. Put the digital multimeter on DC volts. Put one lead of the meter on the boat's now-open ground pin in the boat power plug. Put the other meter lead on the ground lug (or the metal electrical box bare metal which is the same point). You will now measure the DC potential difference between your boat's underwater metal parts, hooked to the ground pin of the boat's power plug...and the rest of the world hooked to the marina ground, including every other boat that's wired like yours is. This voltage will be around 1-2 volts DC, not AC. Any AC voltage you can measure at this point indicates something is bad wrong with the marina's electrical system. There should be no AC voltage between their ground and your boat's connection to seawater...the underwater metals that are "grounded" to AC ground. If you want to see how much current flows when the boat's plugged in, switch the digital multimeter to DC amps. The internal low-resistance shunt in the multimeter is a virtual short, allowing the boat and AC power system to conduct like it was plugged in. That current you see is why your zincs are eating away just before the nice prop was..... Many problems are caused by the boaters themselves. One boat has a faulty battery charger leaking between the DC output and the charger's ground back to the dock. This results in some DC voltage applied to that boat's underwater metal parts, much more voltage than just zincs can produce and, probably the wrong polarity. His boat is now acting like a PLATING MACHINE!....using your zincs to plate his prop! Some other boat hasn't had a zinc in years so his boat causes a big potential difference to yours and others. To find the offender, you need one person standing watching your DC voltmeter reading high and another person going down the dock, NOT SWITCHING BREAKERS ON AND OFF, but unplugging boats, one after another. FRS walkie talkies make this job much easier than yelling between you. When you unplug the offender, the voltage back on your dock drops drastically. THAT guy is eating everyone's zincs and props. Show the marina dockmaster who has a very good reason to get him OFF YOUR GRID as it's eating the marina's electrical system, too! Let us know which boat has the flea market automatic battery charger when you find him..... Japanese battery chargers some have POSITIVE DC hooked to AC ground!....the only AC ground point on his boat so it doesn't short his batteries to operate that way. His prop is +14.2V above yours!...lotsa ground current flows! |
Isolation Transformer and DC corrosion
Russell wrote: Since my post a few days ago, spoke to our marine electrician and the on-staff electrical expert retained by the Harbor office. We are going to have to install an isolation transformer in our dock box. This will cost about $1,000 after parts, labor and some mods to the box. All 90 boats in our harbor that got the notices have to do this, move, or unplug or disconnect the AC ground from the DC, not a good option. So, now I see the West Advisor says that apparently solves the marina's issue with the AC, but unless we separate all the underwater stuff, like the through hulls, we still are subject to DC corrosion. Can this be true? What is the real solution to the AC, the DC, the safety and the corrosion problem? Is there one? We are one of 90 modest boats from about 28-48 feet, mostly 1970's through 1990's vintage. We all have to get these transformers now, but the issue is what else do we need to do once we are on the transformer? Russ, I've never heard such garbage in my life. Lets get this straight, they have a problem with their wiring, and they want you to pay for it? No way. |
Isolation Transformer Vs. Galvanic Isolator
While on the subject, would someone please explain the difference between an Isolation Transformer and a Galvanic Isolator? Do they do different things? Is one better to have than the other? Thanks, Gary |
Isolation Transformer Vs. Galvanic Isolator
Queeg wrote:
While on the subject, would someone please explain the difference between an Isolation Transformer and a Galvanic Isolator? Do they do different things? Is one better to have than the other? Thanks, Gary They have overlapping functions. Both can address the problem of corrosive galvanic currents passing from an unprotected boat through the shore power cable grounding conductor to another boat. If the other boat(s) are protected, they will more rapidly deplete their zincs to protect the unprotected boat through that cable. The galvanic isolator really performs no other function, is relatively cheap, and is easily installed. The isolation transformer isolates a boat's AC electrical system (and usually the DC system as well) from the outside world. This means that if there are certain types of problems with the shore power system, or if there is an unprotected boat connected to the shore power system, the boat using the isolation transformer is protected. In a no-holds-barred contest, the more costly isolation transformer would be the preferred choice. Both devices also protect neighboring boats from your boat if your own zinc should be depleted. It is that spirit of the golden rule that so permeates the cruising community with a desire to leave a clean wake. Do a web search on isolation transformer and one on galvanic isolator. You'll find a lot of interesting info. Chuck ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
All times are GMT +1. The time now is 04:57 PM. |
Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004 - 2014 BoatBanter.com