KirstieH Posted May 25, 2017 Report Share Posted May 25, 2017 Hello. Forgive this potentially dumb question but...i bought a transformer from a chandlery but on delivery the box had been opened and the fixing plate was bent. They have assured me it was not a customer return and if it it faulty i can return it they have replaced the plate.....dum question coming up....how will i know it is "transforming"....its not like a normal product which you can tell is working straight away. It doesnt seem to have lights or an on button. Grrr Link to comment Share on other sites More sharing options...
rusty69 Posted May 25, 2017 Report Share Posted May 25, 2017 2 minutes ago, KirstieH said: Hello. Forgive this potentially dumb question but...i bought a transformer from a chandlery but on delivery the box had been opened and the fixing plate was bent. They have assured me it was not a customer return and if it it faulty i can return it they have replaced the plate.....dum question coming up....how will i know it is "transforming"....its not like a normal product which you can tell is working straight away. It doesnt seem to have lights or an on button. Grrr Is it an isolation transformer? Link to comment Share on other sites More sharing options...
WotEver Posted May 25, 2017 Report Share Posted May 25, 2017 (edited) If you put 230 into one side and it comes out the other side then it's transforming. With it unplugged if you check continuity with a multimeter between the input earth and the output earth and find them disconnected then it's isolating. If you then check for continuity between output earth and output neutral if they're connected then it's N-E bonded. If there is no continuity between output earth and output neutral then you need to bond them yourself. Edited May 25, 2017 by WotEver Typo Link to comment Share on other sites More sharing options...
KirstieH Posted May 25, 2017 Author Report Share Posted May 25, 2017 2 minutes ago, WotEver said: If you put 230 into one side and it comes out the other side then it's transforming. With it unplugged if you check continuity with a multimeter between the input earth and the output earth and find them disconnected then it's isolating. If you then check for continuity between output earth and output neutral if they're connected then it's N-E bonded. If there is no continuity between output earth and output neutral then you need to bond them yourself. I understood 30% of that thank you. Will borrow a multimeter! 4 minutes ago, rusty69 said: Is it an isolation transformer? Yes Link to comment Share on other sites More sharing options...
rusty69 Posted May 25, 2017 Report Share Posted May 25, 2017 1 hour ago, KirstieH said: I understood 30% of that thank you. Will borrow a multimeter! Yes Another 70% you'll be sorted! Link to comment Share on other sites More sharing options...
Flyboy Posted May 25, 2017 Report Share Posted May 25, 2017 2 hours ago, KirstieH said: Hello. Forgive this potentially dumb question but...i bought a transformer from a chandlery but on delivery the box had been opened and the fixing plate was bent. They have assured me it was not a customer return and if it it faulty i can return it they have replaced the plate.....dum question coming up....how will i know it is "transforming"....its not like a normal product which you can tell is working straight away. It doesnt seem to have lights or an on button. Grrr You need to give more information like the model no. It could be an isolation transformer, an inverter, a combi inverter, a battery charger. When you bought it what did you expect it to do? Link to comment Share on other sites More sharing options...
KirstieH Posted May 26, 2017 Author Report Share Posted May 26, 2017 (edited) 9 hours ago, Flyboy said: You need to give more information like the model no. It could be an isolation transformer, an inverter, a combi inverter, a battery charger. When you bought it what did you expect it to do? It is an isolation transformer. Not an Inverter or battery charger (clue in the title) just a plain old Victron 3600w transformer not combi - to deal with the earth current currently working its way through my hull 10 hours ago, rusty69 said: Another 70% you'll be sorted! I will pay someone for the other 70%...it is what they went to school for lol Edited May 26, 2017 by KirstieH Link to comment Share on other sites More sharing options...
Flyboy Posted May 26, 2017 Report Share Posted May 26, 2017 (edited) 10 hours ago, KirstieH said: It is an isolation transformer. Not an Inverter or battery charger (clue in the title) just a plain old Victron 3600w transformer not combi - to deal with the earth current currently working its way through my hull I will pay someone for the other 70%...it is what they went to school for lol Well in that case you put 230v AC into the input and you get 230 AC from the output. The instructions that came with it will make it clear how to connect it up. Be careful when dealing with mains voltages, if in doubt get an electrician to wire it up. Edited to add :- Looking at the manual, you will need to configure it to set the correct voltage and earthing arrangement. The earthing is important so that your RCD will trip if there is an earth leakage fault. Configuring is a simple job using jumpers. https://www.victronenergy.com/upload/documents/Manual-UK-IsolationTransformer1800-3600.pdf Edited May 26, 2017 by Flyboy Link to comment Share on other sites More sharing options...
BoatyMacBoatface Posted June 3, 2017 Report Share Posted June 3, 2017 Thanks for asking Kirstie - I've got a supplementary. The boat we're hoping to buy has a galvanic isolator fitted. Is it a straight swap to fit an isolation transformer? And it worth bothering? Link to comment Share on other sites More sharing options...
rusty69 Posted June 3, 2017 Report Share Posted June 3, 2017 4 minutes ago, BoatyMacBoatface said: Thanks for asking Kirstie - I've got a supplementary. The boat we're hoping to buy has a galvanic isolator fitted. Is it a straight swap to fit an isolation transformer? And it worth bothering? An isolation transformer will be physically heavier and bigger, so its location may require alterations to your wiring. Good info here http://www.smartgauge.co.uk/galv_tran.html Link to comment Share on other sites More sharing options...
Robbo Posted June 3, 2017 Report Share Posted June 3, 2017 9 minutes ago, BoatyMacBoatface said: Thanks for asking Kirstie - I've got a supplementary. The boat we're hoping to buy has a galvanic isolator fitted. Is it a straight swap to fit an isolation transformer? And it worth bothering? IMHO if your on shore power for the majority of the time then a IT is much better choice than a GI. Link to comment Share on other sites More sharing options...
nicknorman Posted June 3, 2017 Report Share Posted June 3, 2017 2 hours ago, BoatyMacBoatface said: Thanks for asking Kirstie - I've got a supplementary. The boat we're hoping to buy has a galvanic isolator fitted. Is it a straight swap to fit an isolation transformer? And it worth bothering? No it isn't a straight swap. A GI is a fairly small device inserted in the earth wire coming from the shore socket. An IT is a large and heavy device that has to be wired to the live, neutral and earth of both the incoming shore supply and the boat's circuitry. Is it worth bothering? There are a number of pros and cons. An IT is perhaps considered the "rolls Royce" solution but if you don't have the space to retrofit one, it's a non-starter. If you have a GI with a monitoring meter or LEDs and you test it from time to time, IMO that is adequate. 1 Link to comment Share on other sites More sharing options...
BoatyMacBoatface Posted June 3, 2017 Report Share Posted June 3, 2017 1 minute ago, nicknorman said: No it isn't a straight swap. A GI is a fairly small device inserted in the earth wire coming from the shore socket. An IT is a large and heavy device that has to be wired to the live, neutral and earth of both the incoming shore supply and the boat's circuitry. Is it worth bothering? There are a number of pros and cons. An IT is perhaps considered the "rolls Royce" solution but if you don't have the space to retrofit one, it's a non-starter. If you have a GI with a monitoring meter or LEDs and you test it from time to time, IMO that is adequate. Thank you I now need to find out about GI monitoring... Link to comment Share on other sites More sharing options...
nicknorman Posted June 3, 2017 Report Share Posted June 3, 2017 (edited) 1 hour ago, BoatyMacBoatface said: Thank you I now need to find out about GI monitoring... A GI comprises some diodes that won't conduct at the low voltages typically found between mains earth and local earth, but will conduct at higher voltages i.e. when there is a major fault condition. If the mains earth is at a higher than expected voltage difference compared to the local earth (which can happen if the local substation/transformer isn't set up correctly), it is possible that the diodes start to conduct and thus the GI becomes ineffective. The idea of monitoring is to alert you of this undesirable situation. Some GIs have a meter, which is handy because if the GI is working you would expect a very slight but detectable needle deflection when you plug the shore power in, and this tells you that the GI is not short circuited. Of course the meter should stay in the green (indicating that the diodes aren't conducting). Some GIs have leds that illuminate when the diodes are near to conducting, but when not illuminated they don't tell you that the GI isn't short circuited, unlike the meter. The LEDs do tell you that there is a slight AC fault, which the meter doesn't, but I'm not sure that an AC fault is significant in terms of hull corrosion. Anyway, important thing with a GI is to test it from time to time and especially if there has been a breaker trip. Edited June 3, 2017 by nicknorman Link to comment Share on other sites More sharing options...
WotEver Posted June 4, 2017 Report Share Posted June 4, 2017 13 hours ago, nicknorman said: Anyway, important thing with a GI is to test it from time to time and especially if there has been a breaker trip. Particularly because not all GIs are created equal. None of the cheaper ones appear to comply with the ABYC specs. Link to comment Share on other sites More sharing options...
Chewbacka Posted June 4, 2017 Report Share Posted June 4, 2017 18 hours ago, nicknorman said: A GI comprises some diodes that won't conduct at the low voltages typically found between mains earth and local earth, but will conduct at higher voltages i.e. when there is a major fault condition. If the mains earth is at a higher than expected voltage difference compared to the local earth (which can happen if the local substation/transformer isn't set up correctly), it is possible that the diodes start to conduct and thus the GI becomes ineffective. The idea of monitoring is to alert you of this undesirable situation. Some GIs have a meter, which is handy because if the GI is working you would expect a very slight but detectable needle deflection when you plug the shore power in, and this tells you that the GI is not short circuited. Of course the meter should stay in the green (indicating that the diodes aren't conducting). Some GIs have leds that illuminate when the diodes are near to conducting, but when not illuminated they don't tell you that the GI isn't short circuited, unlike the meter. The LEDs do tell you that there is a slight AC fault, which the meter doesn't, but I'm not sure that an AC fault is significant in terms of hull corrosion. Anyway, important thing with a GI is to test it from time to time and especially if there has been a breaker trip. Possibly this is rubbish, but I think that if there is a DC voltage present that is less than the diode voltage, then normally the GI will block it, however if there is an additional AC voltage that is just high enough to cause the diodes to conduct, then the combined wave form will be offset from zero, and so will have a DC current during part of the cycle. Therefore there will be a net DC current flow, though it will appear as a pulse train (50Hz), rather than as a continuous current. The mark space ratio being determined by the magnitude of the AC voltage. Link to comment Share on other sites More sharing options...
nicknorman Posted June 4, 2017 Report Share Posted June 4, 2017 10 minutes ago, Chewbacka said: Possibly this is rubbish, but I think that if there is a DC voltage present that is less than the diode voltage, then normally the GI will block it, however if there is an additional AC voltage that is just high enough to cause the diodes to conduct, then the combined wave form will be offset from zero, and so will have a DC current during part of the cycle. Therefore there will be a net DC current flow, though it will appear as a pulse train (50Hz), rather than as a continuous current. The mark space ratio being determined by the magnitude of the AC voltage. Not rubbish, quite correct. So I think we can say that a pure DC voltage is adequately dealt with by a meter, but a lower level dc fault with superimposed AC isn't. Link to comment Share on other sites More sharing options...
WotEver Posted June 4, 2017 Report Share Posted June 4, 2017 16 minutes ago, Chewbacka said: Possibly this is rubbish, but I think that if there is a DC voltage present that is less than the diode voltage, then normally the GI will block it, however if there is an additional AC voltage that is just high enough to cause the diodes to conduct, then the combined wave form will be offset from zero, and so will have a DC current during part of the cycle. Therefore there will be a net DC current flow, though it will appear as a pulse train (50Hz), rather than as a continuous current. The mark space ratio being determined by the magnitude of the AC voltage. Doesn't sound like rubbish to me. In fact, wasn't that Gibbo's main argument against GIs? Link to comment Share on other sites More sharing options...
Chewbacka Posted June 4, 2017 Report Share Posted June 4, 2017 9 minutes ago, WotEver said: Doesn't sound like rubbish to me. In fact, wasn't that Gibbo's main argument against GIs? No idea, but sounds reasonable. Link to comment Share on other sites More sharing options...
smileypete Posted June 4, 2017 Report Share Posted June 4, 2017 (edited) 46 minutes ago, Chewbacka said: Possibly this is rubbish, but I think that if there is a DC voltage present that is less than the diode voltage, then normally the GI will block it, however if there is an additional AC voltage that is just high enough to cause the diodes to conduct, then the combined wave form will be offset from zero, and so will have a DC current during part of the cycle. Therefore there will be a net DC current flow, though it will appear as a pulse train (50Hz), rather than as a continuous current. The mark space ratio being determined by the magnitude of the AC voltage. That is why you have GI with LED status monitor... Will alert to issues with supply earth, or earthing issues on the boat or possibly even a nearby boat in extreme cases. Edited June 4, 2017 by smileypete Link to comment Share on other sites More sharing options...
jddevel Posted June 4, 2017 Report Share Posted June 4, 2017 Not wishing to high jack the topic but Oh wiseones as I`m intending fitting a isolating transformer two questions please. 1) will 16amp size be adequate? 2) Are they able to come with a LED status monitor or do they even need one? Link to comment Share on other sites More sharing options...
nicknorman Posted June 4, 2017 Report Share Posted June 4, 2017 (edited) 1/ yes (presuming a standard 16A shore inlet) 2/ no, not relevant to an IT. Edited June 4, 2017 by nicknorman Link to comment Share on other sites More sharing options...
jddevel Posted June 4, 2017 Report Share Posted June 4, 2017 Thank you Nicknorman Link to comment Share on other sites More sharing options...
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