The other day I was looking some electrical schematics for some carbon sail yacht and I was wondering why there are circuit brakers also on neutral wire? The other thing I didn't understand why there is the need for galvanic isolation and how galvanic isolator is connected. I was looking at block diagram so there are no detailes on connection. But I predict galvanic isolation is done via 1:1 "transformer". Also I don't undestand why the generator is connected behind the RCD - doesn't that mean that RCD will only be functional when shore powered but not when generator powered or battery/inverter powered.
Without seeing the schematic to better understand it, my guess is going to be lightning. Sail boats have a magnificent way about then in an electrical storm.
A carbon fiber hull is conductive and treated as a steel or aluminum hull. Double pole breakers insure complete isolation of the load and provide much more safety. See above, the shore ground is isolated in order to prevent electrical leakage from neighboring boats from creating galvanic corrosion on your underwater metallic bits. Google galvanic isolators to see how they work and how they are wired. Is it safe to assume you are European and RCD is Eurospeak for Ground Fault Circuit Interruptor? If that is the case then I am not sure why the boat would have only one ... these are generally low current devices located at the convenience outlet they protect. If you mean a Reverse Current detector or relay then it should be located so as to prevent power from feeding the generator. They are usually physically located in the switchboard very close to the generator controls and electrically located between the gen breaker and the generator. Modern reverse current detectors provide a signal that opens the generator breaker That depends on what the RCD is ... if it is a reverse current detector then it lives where it should. If it is a giant GFCI then who knows what they had in mind. Also if this thing is in front of the generator doesn't than mean it is between the generator and the rest of the world? Or is it between the generator and its breaker ... where a reverse current detector should be?
That galvanic isolator that Marmot mentions has another useful function, IIRC: You can stand in a puddle of bilge water while operating an electric drill without frying yourself.
That is the intent of a GFCI. A galvanic isolator will not slow the Darwinian technique of yachtcrew selection.
Can you explain more since I do not understand why neutral wire has to have circuit braker - no house electrical system has this. Yes I googled it as you instructed me and I read that there is stray current and galvanic corrosion - this are DC currents of about 1-1.2volts that are generated because different steels act like anode and cathode in electrolite - salt water and so we use diode pack on GND shore wire that has knee of about 1.5V so only currencts higher than 1.5 can flow. Yachts have also immersed zincs connected to ground bus bar (also DC negative bus bar, AC earth bus bar and ground plate are connected to this bus bar) to prevent corrosion. Al the immeresed metal parts (bow thruster, propellers, shaft, rudders...) must be connected to groun bus bar. But why on this electrical schemes carbon-fiber sail yacht have isolation transformer (1:1 ratio) on L and N wire and no isolation on GND, when glass-fiber power yacht use diode pack on GND and have no isolation transformer? Yes. I meant Residual-current device - same device every house AC systems should have + separate one (more sensitive) for bathroom. As I read RCD measures current flow on L1, (L2,L3) and N wire. If this difference is greater (human touching live wire) than rated (30mA) then RCD will disconnect preventing human to be electrified. Now if I understand this yacht's block diagram the system is powered via shore or via generator/battery. There is a selector switch since the system can not be powered by both sources at the same time - syncronization problem I gues. Generator is connected to the system by ONLINE method, menaing there is no interuption. When yacht is off shore 24V DC buses are powered directly from 24V battery pack, 12V DC buses are powered via DC/DC converter, AC buses are powered from 24V battery pack via 230V, 50Hz inverter. Generator and shore (there is shore/gen selector switch between) are both connected to the lead-acid gel batery pack via 24V Mastertvolt generator charger, that I assume has transformer and rectifier inside + charger program logics and temperature control. On the schematics there are also battery isolator - what that is - have no clue, but I gues this is just diode pack so current flow can only be from batterys not to it, since batt charger has its own connection. Back to the RCD - I know RCD does not protect in case there is an isolation transformer (on this schematics examples carbon-fiber sail yacts have this, when glass-fiber power yachts have diode pack as galvanic isolator) between shore and AC consummers, so I gues there is no need for it. But why is inverter that is connected to the batterys on one side, conected after RCD on the other side? Doesn't this mean that RCD will only protect when shore powered but not when battery/generator powered via inverter? BTW can you tell me how can 50Hz AC electric standard yacht connect to US marina and vice versa? Does it need to have rectified shore and than inverted to 50Hz or 60Hz shore power is rectified any connected only to battery charger - so you use inverter connected to batterys?
Here are aslo URL to single line and block line diagram examples if you want to look at - I must say that with my knowledge this system isn't logic! http://www.filesupload.com/ow4EH9xbg http://www.filesupload.com/LL8YFq I aslo made my own simplified schematics as I see what yacht electrical system should look like (only AC/DC no bilge system, fire detection, radios, navigation, Air condition, toilets...). Its free to comment.
hello shipman yes you can say this agian the shema in your commont is not logic at all and even have mistake in it like * in the 230v fuses you draw (dont know if you draw it your self) a dubbel pole automict fuse and a neg bus bar but you connect the phase on both poles so this mean your are going to give it a 2x a phase the right way is that you connect the phase and the negetaive on it * your batt charger is not behind a fuse. * you always need to run your genset to get 24/12volts why do you have batt onboard?? *and when your are sailing before you have 230v you have to run your genset to charge your batt so that they can feed the invertors that dont supply your transformer to get 24/12vols where do you get this from ?? * the transformer looks like 2x 24volts can you not get it with 12v and 24v in it save a dc/dc converter * and why dont you take it all on 24 or 12 volts nav equipment works between 10 and 30voltys any way did is just a fast comment what i can see you fast
it is a single pole circuit braker - I forgot to draw space between circuit brakers. Bellow schematics is repaired. I only lead L wire across the circuit braker since I don't know why N wire should have its onw fuse. (same principle as in house shematics) batt charger has its own fuse - it is not shown here No I don't. DC consumers can be powered directly from battery pack. It is true however that diode on negative wire from battery wasn't directed correctly - my mistake (I made this schematics in 10 minutes). sorry mate but your english is hard to understand. Yes it looks like transformer/rectifier, but manufacturers mostly offer DC power supply units that don't use transformers - so it is meant as DC power supply. There are two of them connected in paralel, so they can prowide neccesary current. (in real case there will probably be more than 2!) And no I can't get 12 and 24V transformer, since I will need DC/DC in any case. When there is shore power I could use two separate transformers 12 and 24V, but when battery powered I will still need reduction from 24V to 12V. I could power 12VDC bus from one battery but then I will drawn power only from that battery and this is not OK since I can have large 12VDC consummers. The other thing is that most yachts that I saw had 4 12V large batterys connected in serial to form one 48V pack and there were several packs connected parralel. I thing this was due to wire limitations and because there were 4 48VDC hydraulic motors onboard that need this voltage. All other DC devices was 12 or 24V and was powered from same battery pack via DC/DC converters. I agree but yachts bild here almost all have 230 VAC and 12/24VDC systems. So I provide all three posibilitys.
I aslo attached more complex schematics that were used on real yachts - thought that some coments will be round them. The thing that I still don't know is why some schemes have isolation transformer, why is good to lead N wire accros the fuse and do yachts have option to be connected to US and EU electrical standards?
sorry about this bad typing but i mean to say is that you use a strange construction to get 230v when you are not using your shore connection it seems that you run your genset (generetor) to use (only) your charger that charge your batt and on ther turn they supply you your 230v on your panel and if you want to support both 12 and 24 than you wil need indeed dc/dc convertor and to answer your last question it is better to always run the zero to your auto. fuse it is saver and it will always be AC running to the wires the transformer is a option and depens on your wallet or lazyniss of installing you dont realy need it the system still will work but it is mutch saver to have it on board but a normal transformer you will not get it working on boths side of the world (usa and eu ) this is simple because usa is 120V 60Hz and eu is (beside england) 230V 50Hz and all your pumps are not made for this to run on both but you can buy a "shoremaster" from mastervolt than you design your both like you want 120v 60hz or 230v 50hz and then it thas not matter what the shore is giving you it will convert it in wath you need but can i ask with wath program you made this ?? owwyea dont forget a shunt in your negative wire before your batt and after your load , to read your Amp use this it is basicaly for sure i will forget something but on this way the other can give more comments (and sorry if i make some typo's it is not a gramma test over here so far as i know )
Thanks I will but still I do know something and however you could explain why the need to have fused neutral wire and what is isolation transformer for and how it is connected? It won't take a minute of your time.
I see generator/battery powered system pretty much same as UPS devices. When you can parrallel DCs if they have the same voltage you can only paralled ACs if they have the same voltage and frequency that must also be synchronised. So knowing these you can built ON LINE or STANDBY systems. In STANDBY system you use either generator or battery/inverter power and you must use a switching method - that means you interupt power when switching. On the other hand in ONLINE method you divide and rectify the generator output and charge the battery. Then you supply DC buses directly from battery and AC buses via a inverter. There is however waste of power in this mode, but since normaly batterys provide power supply for onboard consumers most of the time when generator is off, this is OK. Generator is used only for a biref moment to charge the batterys when their voltage is unsuficient. However I can understand that if the yacht has a big AC consummers onboard (like AC powered winches or AC powered hydraulic motors or AC powered bow and stern thrusters or AC powered Air Condition compressor) that are constantly used more suitable method will be STANDBY mode. But on sail yacht that I know all winches and thrusters were hydraulicaly powered and hydraulical system was powered by for 5KW DC motors and had huge hydraulic/pneumatic reservoar that could cover big and short peaks of demanded power. And since I don't know what kind of constant power consumption there is on yacht other that washing machine, TV or other entertainment I thnk it is more suitable to use ONLINE method. However we did use STANDBY mode since navigation system had separated circuit and batterys and was desiged by online method. Water boiler wasn't electrical, it used diesel fuel to heat water and distillation unit also wasn't electrical it used generator/power motor exhaust heat to make fresh water from sea water. I didn't design electrical system, not to be confused. I had completly different task. As I see it you have two possibilitys when combining US and EU electrical standards. One thing is for sure owner must deside weather he/she will have EU or US standard onboard - since having both will be unpractical. Then builder have basicaly only one option - to divide or multiplie the shore voltage, rectify the current and then lead it to the proper inverter (US or EU el standard compatibile). But as I know up to 30% VA is transformed into heat at this kind of treatment. AutoCAD 2007, there are however many more suitable programs to design electrical schematics. I also use Rhino and Catia. All learned as a hobby. I searched on wikipedia about SHUNT but it says that shunt is like a bypass - don't really know what this means.
A piece of equipment (device) supplied with single phase power should have a safety ground connected between its housing and the hull or ground bus; a line wire; and a neutral wire. The device should be capable of being isolated by a DPDT switch which breaks both the line and neutral. The neutral and line may be fused at the distribution panel or subpanel. This is to eliminate any possibility of power being fed to the device by a fault elsewhere that energizes the neutral wire. The short version is an isolation tranformer is installed to protect the primary side from faults on the secondary side.
