Marine Galvanic Isolators 101. First Part

okay so hey welcome to the shop uh today we talk about something that the past few years we've all become very familiar with uh let's talk about isolation and all the fun things that come with it such as like talking to everybody through plexiglas and dealing with foggy glasses and trying to maintain your social distancing oh come on guys i just want a hug stay back six feet okay but so hey so that kind of isolation that's not fun today we're talking about is galvanic isolation and galvanic isolate tours i've encountered a little bit of confusion i guess with some boat owners about galvanic isolators and what they do and what they don't particularly uh the scenario is uh usually we're going to we're talking about the boat is tripping ground fault breakers in these new marinas and the owner will say something to the effect of uh i don't understand why this is happening i had an isolator installed and uh what's happening is the you know we got a little bit of a mix up between galvanic isolator and isolation transformer they do very different things so what i want to talk about today is what galvanic isolators are designed to do what they're not designed to do and why you might want to get one okay so i had originally thought that this would be just a one video about galvanic isolators but the more i dug into it i realized that in the interest of keeping these episodes bite-sized and easily digestible we're going to break it up into two so this video we're going to talk about galvanic isolators 101 the very basics of what a galvanic isolator does what it doesn't do and how it works on your boat and next video we're going to talk about uh differences in galvanic isolators because there's a lot of different ones out there and it is very important to pick the correct one for your boat and for your application and uh we'll also show you how to test one and see if it's functional so um be on the lookout for that second video uh isolation transformers uh that's a whole other uh subject if you like we can take a deep dive into isolation transformers uh let me know in the comments and uh if you'd like we'll get a uh isolation transformer video out there too so stick around okay so the difference between an isolation transformer and a galvanic isolator comes down to an isolation transformer allows you to power your boat through the magical mysticisms of magnetic fields and electricity we can power your boat without having a physical connection between the boat and the dock therefore it's isolated a gallon isolator on the other hand is designed to block small amounts of dc current from either entering or leaving your boat by means of the ac safety ground the green wire and your short cord while still allowing the ac safety ground to be intact so you might ask why is dc current on my ac ground and why do i care so to explain that let's go over to the whiteboard of nautical knowledge and i'll explain that and why this is a good idea okay so here we are in front of the whiteboard of nautical knowledge um you know the purpose of a galvanic isolator like this is to block dc current from leaving or entering your boat by means of the ac safety ground thereby preventing corrosion to galvanic corrosion between your boat and the next boat or the boat down the dock to explain why that happens let's get into just a little bit of theory is always fun so in order for galvanic corrosion to occur we need to have four elements there has to be four things present in order for galvanic corrosion to take place and just by the way um we're talking about marine interest here this is just marine so in order for galvanic corrosion to take place on our boats we need to have four things and those four things are we need to have a cathode which is uh the metal of the metal on a boat that's more positively charged an anode is metal on a boat that's more negatively charged there needs to be a metallic path that will allow electrons to flow between the anode and the cathode and we need to have our anode and our cathode bathed in the same electrolyte so if we have corrosion we've we have a galvanic cell created here if we remove either one of these elements the corrosion will stop the flow of electrons and ions between them will cease so what we're trying to do with this device is interrupt this process by removing one of these elements okay so this is when the party gets started let's say uh for instance we we're this is our little boat here in the middle and we just pulled into our marina and we're gonna plug into our dock now uh the green that you see here this represents the ac safety ground on the dock which is unbroken down the dock all the way back to the source of power there is nothing in here that interrupts the ac safety ground except a galvanic isolator so we're in our boat here and we pull into our slip and we plug in so we've plugged in and we've joined our ac safety ground with his ac safety ground his ac safety grip now inside the boats there is a point called the common ground point and at that point the dc negative the ac safety ground and the bonding system if you have one all joined together now what we've done by doing that joining the bonding the dc negative and the ac safety ground all together is we've created a metallic path between our prop between our tanks between our struts and any other underwater metal through the ac safety ground to the boat beside us and to the boat beside hemp we're all joined together it's one big collective so if you are in this boat you are sharing your anodes your zincs uh with this guy over here by means of the ac safety so if one of these boats tends to be let's say uh this guy over here is very enotic he is the most negative of the bunch and our boat here is more cathodic electrons are going to flow from this boat into this boat and ions are going to flow out into the electrolyte off the underwater metals so our boat over here is giving up metal its sacrificial anodes its props and all its underwater metal are giving up electrons to the boat beside it so right here we've created a continuous loop we've made our galvanic cell and we think well how do we go about interrupting this uh we can't really we can take our boat out of here we remove the cathode or we remove the anode the process will stop we could remove the electrolyte get them out of the water the process would stop not really a practical thing to do or we could what if what if we cut the safety ground on our boat i know how to deal with this i'll cut this wire and stop that process i would not do that if i were you bad idea yes yes yes very very very bad yeah i would have never done okay so in case you missed that subtle hint um cutting the green wire never a good idea never cut the ac safety ground unless it is to install a galvanic isolator uh cutting this and leaving your boat ungrounded real bad idea not good will your boat still function if you cut that green wire yes it will will your car still drive if you don't have a seat belt yeah but at some point you might need that it's it's don't don't cut the green wire okay so don't cut the green wire but we still have to interrupt this process because we're sharing our anodes and our underwater metals with the rest of the marina this is the one case where you really want to be selfish because as electrons are leaving your boat in this loop you're breaking down the metals uh on the on the molecular the atomic level and the stuff that holds the molecules together is being broken down and we're corroding so the way we handle that is we install a galvanic isolator now inside a galvanic isolator basically all it is is a set of diodes so we have a diode going this direction and we have a diode facing that direction so we have two diodes in opposition which prevent dc current from going one way and from coming the other way but if we have an ac ground fault on board our boat that much voltage will overwhelm the diodes and pass through and that way we've interrupted the flow of dc current without interrupting the flow of ac fault current okay so that's our show and uh about galvanic isolators part one um stick around for part two it'll be great trust me and always remember isolation can be fun galvanically isolated can be fun and remember always like a good neighbor stay over there

Channel: Workin' on a Boat

Views: 7,520

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Id: 9YEcMtbGgeU

Length: 11min 34sec (694 seconds)

Published: Mon Feb 28 2022