Does anyone have the old information from the Yandina website that gave instructions for building a Galvanic Isolator? They have taken the information off of thee web site.
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Yikes! Why do this yourself?
Bill, while I realize some may want to do this just to mess around with it, you are aware that these things are commercially available now? (see web sites for West Marine, etc.) Since they have to be properly linked to the boats' AC electrical system there's a lot of risk and liability if it's done wrong--why not leave it to the pro's?...
Bill, while I realize some may want to do this just to mess around with it, you are aware that these things are commercially available now? (see web sites for West Marine, etc.) Since they have to be properly linked to the boats' AC electrical system there's a lot of risk and liability if it's done wrong--why not leave it to the pro's?...
It is a very simple device
as I understand it. Just a few diodes that cost only a dollar versus a "marine" part that costs a hundred dollars. As I recall, it is two or three pairs of diodes back to back and the pairs are connected in series. You should use a fairly high rating 20-30 amps or so. Silicon is best and gives you 0.7 volt drop for each. Two will give you 1.4 volts and three will give you 2.1 volts but that is probably overkill. Is that a clear enough description for you, Bill?
as I understand it. Just a few diodes that cost only a dollar versus a "marine" part that costs a hundred dollars. As I recall, it is two or three pairs of diodes back to back and the pairs are connected in series. You should use a fairly high rating 20-30 amps or so. Silicon is best and gives you 0.7 volt drop for each. Two will give you 1.4 volts and three will give you 2.1 volts but that is probably overkill. Is that a clear enough description for you, Bill?
Got my diodes picked out
I already have my diodes picked out, just wanted to see what the pro's were recommending, you are right though, it is a very simple concept.
I already have my diodes picked out, just wanted to see what the pro's were recommending, you are right though, it is a very simple concept.
Diodes
What diodes are you going to use and do you have a wiring diagram you would like to share with some of us?
What diodes are you going to use and do you have a wiring diagram you would like to share with some of us?
Diodes
I was going to use 75AMP 600V power diodes, But I would sure like to know what the old Yanida web site suggested.
I was going to use 75AMP 600V power diodes, But I would sure like to know what the old Yanida web site suggested.
Diodes
75 amp diodes seem a big HUGE for isolating direct current from your ground or earth. The currents involved are miniscule.
75 amp diodes seem a big HUGE for isolating direct current from your ground or earth. The currents involved are miniscule.
My guess would be
just about any of the 1N4000 series would work. The PIV rating should not be an issue in this application. I think the 1N4000 series diodes are rated at 10 Amps if memory serves. They are fairly small and very cheap - something like 10 for a dollar. Someone please correct me if I am wrong on any of this.
just about any of the 1N4000 series would work. The PIV rating should not be an issue in this application. I think the 1N4000 series diodes are rated at 10 Amps if memory serves. They are fairly small and very cheap - something like 10 for a dollar. Someone please correct me if I am wrong on any of this.
Don't forget your service rating
Remember that those diodes must handle at least the rating of your shore power service. If there is a short to ground, they must pass the full current of your service eg 30AMP so that your main breaker will open. I guess if your main fails, they will need to take out the shore power service breaker.
Remember that those diodes must handle at least the rating of your shore power service. If there is a short to ground, they must pass the full current of your service eg 30AMP so that your main breaker will open. I guess if your main fails, they will need to take out the shore power service breaker.
A Little Clearer wiring diagram (Sorry Fred)
Found a wiring diagram still need to know type and part number of diodes
Found a wiring diagram still need to know type and part number of diodes
Galvanic Isolators
I generally agree that Galvanic Isolators are best designed and built by professionals. However, FWIW: ABYC standards specify that the isolator must be capable of carrying 135% of the rated shore power current, in the event of malfunction in the AC breaker/circuit protection. ie: 30A 120V Shore Power requires 41 Amp rating. ABYC also requires the Isolator to equipped with a Status Monitor that provides an audible or visual indication that a fault has occurred. ABYC also requires that the indication must be readily apparent to the vessel operator (often requiring a remote monitor panel). The Fail-Closed (to short cct.) design is essential, and required for any shore-based application under the National Electrical Code (NEC), according to the effective grounding path requirements of section 250. This retains safety grounding, in the event of a failure, avoiding a potential hazardous situation. However, ABYC does not explicitly require ship-based electrical systems to meet the effective grounding path wording of the NEC, and therefore galvanic isolators, that have not been designed and tested to this requirement, could Fail-Open, resulting in injury or death. The current ABYC Standard A-28 lists the testing sequence of a Galvanic Isolator which includes AC Conductivity test, Galvanic Current Blocking, (AC superimposed Galvanic Current Blocking - if Capacitor Equipped), Vibration Test, Shock Test, Temperature Test, Short Circuit Test (Interrupting Capacity = 3kA for 30A), Strain Relief Test, and Ignition Protection test (if applicable). The requirements in general state that isolators be tested by an independent laboratory to establish the isolators compliance with this standard and that isolators be provided with instructions covering installation requirements including a complete set of electrical instructions with diagrams. Anyone interested can email me a fax number, and I’ll fax a copy (12 pages). The National Fire Protection Association also diagrams, and issues standards in a properly constructed and installed galvanic isolator. Regards, Gord May Gord@BoatPro.zzn.com
I generally agree that Galvanic Isolators are best designed and built by professionals. However, FWIW: ABYC standards specify that the isolator must be capable of carrying 135% of the rated shore power current, in the event of malfunction in the AC breaker/circuit protection. ie: 30A 120V Shore Power requires 41 Amp rating. ABYC also requires the Isolator to equipped with a Status Monitor that provides an audible or visual indication that a fault has occurred. ABYC also requires that the indication must be readily apparent to the vessel operator (often requiring a remote monitor panel). The Fail-Closed (to short cct.) design is essential, and required for any shore-based application under the National Electrical Code (NEC), according to the effective grounding path requirements of section 250. This retains safety grounding, in the event of a failure, avoiding a potential hazardous situation. However, ABYC does not explicitly require ship-based electrical systems to meet the effective grounding path wording of the NEC, and therefore galvanic isolators, that have not been designed and tested to this requirement, could Fail-Open, resulting in injury or death. The current ABYC Standard A-28 lists the testing sequence of a Galvanic Isolator which includes AC Conductivity test, Galvanic Current Blocking, (AC superimposed Galvanic Current Blocking - if Capacitor Equipped), Vibration Test, Shock Test, Temperature Test, Short Circuit Test (Interrupting Capacity = 3kA for 30A), Strain Relief Test, and Ignition Protection test (if applicable). The requirements in general state that isolators be tested by an independent laboratory to establish the isolators compliance with this standard and that isolators be provided with instructions covering installation requirements including a complete set of electrical instructions with diagrams. Anyone interested can email me a fax number, and I’ll fax a copy (12 pages). The National Fire Protection Association also diagrams, and issues standards in a properly constructed and installed galvanic isolator. Regards, Gord May Gord@BoatPro.zzn.com
Thank you Gord!
That is very good information if a little gnarly (?sp). I must confess that I have never looked at this subject in such detail and I stand corrected. Thanks. Where is a capacitor connected to provide "AC superimposed Galvanic Current Blocking"? Do you have a diagram and or specifications? I am surprised to learn that an indicator is needed. Is that the light on my electrical panel which says "reverse polarity"? I have never given that light much thought since it has never come on except to test. Can this visual indicator be a simple led or should (or could) it be a back to back pair of them?
That is very good information if a little gnarly (?sp). I must confess that I have never looked at this subject in such detail and I stand corrected. Thanks. Where is a capacitor connected to provide "AC superimposed Galvanic Current Blocking"? Do you have a diagram and or specifications? I am surprised to learn that an indicator is needed. Is that the light on my electrical panel which says "reverse polarity"? I have never given that light much thought since it has never come on except to test. Can this visual indicator be a simple led or should (or could) it be a back to back pair of them?
Status Monitor
No, a “Reverse Polarity” indicator is required whether or not you have a “Galvanic Isolator”. It indicates a reversed connection (Hot Neutral) on the shore-side wiring. The “Status Monitor”, on a Galv. Isolator, indicates an otherwise unrecognized failure in the isolator, including: a) Shorted or Open Diode b) Failure to block Galvanic Current @ 1.1 VDC c) Grounding circuit continuity etc It's a fairly complex circuit. I hope, by now, everyone understands that I DON'T think building a Galvanic Isolator is a good D.I.Y. hobby project. There's a lot more to it than just 4 diodes and (perhaps) a capacitor. Gord May
No, a “Reverse Polarity” indicator is required whether or not you have a “Galvanic Isolator”. It indicates a reversed connection (Hot Neutral) on the shore-side wiring. The “Status Monitor”, on a Galv. Isolator, indicates an otherwise unrecognized failure in the isolator, including: a) Shorted or Open Diode b) Failure to block Galvanic Current @ 1.1 VDC c) Grounding circuit continuity etc It's a fairly complex circuit. I hope, by now, everyone understands that I DON'T think building a Galvanic Isolator is a good D.I.Y. hobby project. There's a lot more to it than just 4 diodes and (perhaps) a capacitor. Gord May
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