mains The Mains Electrical Thread

[TheQ]

The 240V  electrolytic action is where an Isolation transformer or galvanic isolator is required, to stop interboat electrical  currents. In theory once afloat and not connected to shorepower because you have no return circuit you should no problems.

[TheQ]

Many houses in Norfolk also depend on a local earth.

Not long ago I turned on the bathroom heater and the Garage ELCB started smoking!! after much chasing around I found the Heater had gone short Live to Earth , but a previous replacement of the House Gas boiler / immersion heater with a combination boiler (by professionals) had broken the earth line. Meaning 230v was fed to anything in the house and garage on it's earth.

Since the ELCB was now being powered from the wrong side via the heater earth it was impossible to switch off.

The ELCB has been replaced by an RCD, plus  a new heater, earth rod and earth line fitted

 

[grendel]

I now have all of our electrical design engineers scratching their heads over how to earth an inverter, common consensus seems to be to earth the case to an earth point, but then we still get the same discussion as above as to where that earth point should be in a boat.

[TheQ]

3 minutes ago, grendel said:

I now have all of our electrical design engineers scratching their heads over how to earth an inverter, common consensus seems to be to earth the case to an earth point, but then we still get the same discussion as above as to where that earth point should be in a boat.

Nothing like a bit of brain power on the task, I hope they come up with a solution we can all be happy with!!!

 I've no view as to what is the best way to do it, I'm just reporting what I've read elsewhere and hoping someone comes up with a good idea before I do my wiring...

[BroadScot]

As my electrical theory tutor at day release college said in 1964 Electricity is not an exact science ! Reading the threads here, he may well have been right !

Iain

[ranworthbreeze]

Hi Iain,

I used to like the practical in the workshops where you had to wire a surface installation on boards, it used to be a pain because of the tight bends  in the cables in order to keep them on the boards.

Sadly a few pranks where often done whilst people were away from their boards, such as undoing a lamp or switch and cutting off the connection cable and then just tightening onto the insulation etc.

I always liked working on three phase and diesel generators and spent many hours on commissioning up to 5 hours on full load and then an hour on overload, all to charge batteries in the exchanges back in the day.

Regards

Alan 

[BroadScot]

Hi Alan

4 minutes ago, ranworthbreeze said:

used to like the practical in the workshops where you had to wire a surface installation on boards, it used to be a pain because of the tight bends  in the cables in order to keep them on the boards.

In those days it was buckle clips and brass pins, to dress cables as i'm sure you remember, the skin off the end of your fingers was quite common till the skin hardened up ! As for pranks, nah I was a .

Iain

[Vaughan]

1 hour ago, BroadScot said:

Is this any good to answer your question Grendel ? http://www.projectboatzen.com/understanding-inverter-installations/

Iain, this link you have given is very, very relevant.

It is American so they are talking 110 volts and also remember that American regs require everything in the boat to be electrically bonded, steel hull or not.

I recommend all on this thread to read this link very carefully and then read it again. Almost every sentence contains important points.

There is a picture of the power panel which I would like to post, so as to discuss it, but I don't know how to. Can you post it for me?

All the same, they still don't actually specify where the earth is supposed to be going!

 

 

[BroadScot]

5 minutes ago, Vaughan said:

There is a picture of the power panel which I would like to post,

This one Vaughan?

[ranworthbreeze]

Hi Vaughan,

 

Is this the picture you wanted?

 Regards

Alan

[Vaughan]

3 minutes ago, ranworthbreeze said:

 

Alan

Lovely, thanks Alan (and Iain).

This is very similar, in principle to the Peachment panel that they fit with hydraulic generators.

 It has a voltmeter, which I think is obligatory in EC regs, and an ammeter, which may be needed in US regs. It is shown connected to shore power and as there are two, this probably means one for the domestics and one for the aircon, so this will be coming in through two shore plugs.

The generator and inverter are off and are protected by blind flaps, much as you would find in an aircraft. In the centre are two buttons marked start/stop and preheat and these are used to remotely start the generator, which I would guess is an ONAN, as they are most popular in the States. Even having started the generator it will not be connected to the circuit unless you lift the blind flap and raise the generator switch. This will immediately trip off the two shore power circuits. Same result if the inverter were connected (which would trip off the shore power) and you tried to engage the generator. So only one at a time.

The one at the right marked Parallel bus A+B is, I think, having read the article, to parallel the two return buses if you are not using shore power. I also notice that the shore power switches have three poles, as they contain an earth, but the other circuits do not.

The two reverse polarity lights are not glowing so polarity is normal from the shore.

 

[Viking23]

Inverters can create their own problems or confusion.

The output of the standard mains is the live wire is the one that alternates, positive then negative 50 times a second, the neutral at the power station or local substation is bonded to earth so under normal circumstances the neutral wire doesn't carry a lethal voltage. I said under normal circumstances, there are many situations when this may not be true, phase fault on one of the three phases, poor ground in the local area of the consumer plus many others.

However, most inverters do not earth the neutral, some split, so at one instant the live is at +120 V ac and the so called neutral at -120V ac, so the difference is 240 V ac

Some inverters are known to have floating outputs, so if either the neutral, or live became earthed ( but not both lol)  then the supply wouldn't be cut and will continue, putting 240 V ac on the neutral  if the live was accidentally connected to earth.

Loose an earth when all this is going on, and you may find that the earth leakage trip will not work, and people are at risk of electrocution.

Incidentally, those 3 lamp plugs you plug into the mains socket to check if Live is Live......   Earth connected etc can show a fault when plugged into a supply from an inverter which is centre tapped. ie + 120 /-120 etc

Think about wiring your boat with shore power and an inverter? Do you have the expertise to do this?

 

[BroadScot]

7 minutes ago, Vaughan said:

The two reverse polarity lights are not glowing so polarity is normal from the shore.

The ones on a panel down in an engine room on coal boats was a simple bayonet holder and pygmy lamp !  Nine times out of ten it was a joiners nail that had bridged a fuse point !!

[grendel]

from the looks of it the flaps on the board shown by Vaughan are interlocks, they slide on the rail, so that the power cannot be used from the generator until the shore power breaker is switched off and the interlock plate slid over the shore power circuit, before the generator can be used, ditto the inverter the interlock plate has to be moved across the shore power 2 before it can be switched on. there is also an interlock plate on the switch that connects the two halves of the panel (A+B), I presume the generator feeds side A and the inverter side B so the interlock plate will switch off one of those before allowing the whole board to be fed from a single source.

[riyadhcrew]

That is the same as a castell key system for bus couplers. You can't switch one on until the other one is off.

[TheQ]

Grendel I think your interpretation is correct, it's something I will be imitating by using a inverter--- centre off --- generator switch to the onboard mains supply ( on live and neutral).

In the link posted by BroadScot from projectzen, is a circuit diagram, it is what I am roughly intending to imitate. The earthing problem is of course still to be decided.

For the reason Viking23 says, my panel equivalent of those 3 light plugs, is to be on the shore power side of the inverter/ shore power switch. One would hope it would never be needed on the boat permanently wired side of the boat, after the installation. I do have one of those plugs and would use it as a final check, on any mains sockets fitted onboard ( or anywhere else).

[TheQ]

Oops that should be inverter--- centre off --- shore power  switch to the onboard mains supply 

[Viking23]

The simplest and cheapest way of incorporating an inverter and shore power whilst incorporating the main RCD is...

You have a 16 Amp blue plug connected to the input of your RCD. Mcbs etc

You have a blue 16 Amp socket  on your inverter output.

When you want shore power connect RCD plug to your shore lead, if you want inverter, simply plug RCD plug into the inverter socket.

No clever switches, no contactors, you can never connect the inverter to the shore power, putting others at risk...

Fool proof, most probably.

Idiot Proof, not always, someone might get their plugs and sockets cross wired !

So far two BSS inspectors from different waterways like the simplicity.

Clearly the plug socket arrangement needs to be in a dry area.

There is one slight thing, when on inverter only, you have to make sure that you turn the battery charger breaker off lol, otherwise you will be charging the battery, by discharging the battery at the same time lol... resulting in a net loss in battery charge.

 

[TheQ]

Right now you mention battery charges here's a problem I do have to sort.

The panda - fisher generator charges a stack of 24, 2v traction batteries. What it doesn't have is a 12v charging circuit for its own car type starter battery.

What would be the best way of charging this battery when not on shore power,

note I do have a small solar trickle charger.

[riyadhcrew]

Not sure about this one Q. What would be the charge voltage at each 2V cell? Is it possible to connect the 12V battery across 6 2V batteries and get 13 or 14 volts? I'm thinking out of the box here.

[TheQ]

25 minutes ago, riyadhcrew said:

Not sure about this one Q. What would be the charge voltage at each 2V cell? Is it possible to connect the 12V battery across 6 2V batteries and get 13 or 14 volts? I'm thinking out of the box here.

The worry would be if I'm wanting to start the generator, then any 6 of the 2v batteries might not have enough voltage / current left, to charge the starter battery. I could do with  a circuit that would use 12 or all 24 of the 2V batteries to charge the 12V battery to full charge.

[Vaughan]

On the Crown Blue Line circuits developed in conjunction with Peachment, the engine battery does NOT take part in any of this. It is not charged by the shore power, generator or inverter as it is always fully charged by the engine, just as it would be in a vehicle. This also means that it can remain independent of 24 volt circuits if necessary. What we are talking about are "domestic" circuits, to power domestic equipment.

I agree that the panel shown in my last post appears to have a mechanical slide arrangement to effect the blocking of one circuit from another. A bit like the blocking of signals on a railway, if you like. The Peachment panel does this electrically, so if you engage the generator when plugged into shore power there is a very loud "thunk" from behind the panel and the shore power circuit trips out. I don't know what kind of electronic box they use to achieve this, but it is definitely HIRER PROOF.

And excuse me but we have been discussing this all day but the question is still the same. Where does the earth go?

[grendel]

Vaughan, I believe the answer to that is nobody really knows, certainly none of the electrical design engineers at work know (and they are all graduates of various ages) they all know how not to earth (things like steel framed buildings) but none have a definitive answer. at work we get various documentation coming out, the latest was the hazards of a floating neutral in single phase supplies off of a 3 phase main.

One was even experienced in oil rig (in marine environment) supplies, but that is all explosion proof this that and the other.

[TheQ]

If you follow the American system shown by BroadScot links (Projectzen), then Mains earth and DC Low are connected together. Since an engine, metal work and the Sacrificial Anode are connected to DC Low then it's the Sacrificial Anode that provides the earth. Better alternatives than this, no one has yet suggested.

Although... I wonder if you could have a one anode for the engine and your metal work and another separate anode for AC earth?

 I would have liked to keep my Starter battery totally separate from the drive system, but as the Panda-Fischer is a quiet boxed unit, there is absolutely no provision for a separate alternator nor anywhere to fit one. it is a most peculiar omission by Panda -Fischer

[BroadScot]

1 hour ago, Vaughan said:

And excuse me but we have been discussing this all day but the question is still the same. Where does the earth go?

Errr roon the Moon?   Sorry tried to resist all day ! 

Iain