mains The Mains Electrical Thread

[BroadScot]

1 hour ago, TheQ said:

While BroadsScots solution will work, i

Yep it will work and is a cheap solution with no tools or connecting required, just plug it in.

[TheQ]

Yes it can be done , that is to synchronise the Generator to the mains, But it is quite expensive, all those solar panels on house rooves,  send DC through to an electronic box to do it, as they generate DC, which has to be inverted and synchronised. However synchronisers are expensive, definitely just buy a 32A cable...

 

The synchronisation is needed because 230V is AC, that is Alternating Current, if you were to connect a generator while one was + 230V and the other was at -230V, you'd get nothing out but a large cloud of smoke and maybe a little fire...

[Vaughan]

8 minutes ago, LondonRascal said:

Could a generator be used to provide the additional current to the boats electrical system - and could it have some current sensing to 'call for the generator' and provide the boost when required I wonder.

In a word - No.

We had some boats with Peachment's hydraulic generator to run air conditioning and the panel was installed by them with trips to prevent this happening. So you either power it from the shore or by the generator. There is also the possibility, in the case of a power failure, that you may end up powering the street lights on the mooring, via your own generator!

You and I have talked of air conditioning before, and it takes a lot of power. All of Crowns boats had a 32a socket as standard, and American boats have two. 32a for the domestics and 50 a for the aircon. In American marinas on big cruisers the aircon is running the whole time whether the owner is on board or not.

[TheQ]

I think Vaughan and me have just given the answer from different angles!!

[Bound2Please]

23 minutes ago, LondonRascal said:

Could a generator be used to provide the additional current to the boats electrical system - and could it have some current sensing to 'call for the generator' and provide the boost when required I wonder.

 

Robin going back to the mid 1980's, British Rail had standby 660v generators for our department. in the event of power failure, so that signals etc kept working they would kick in, in the event of a power cut. But once power restored to the power house, we had to go man manually stop the generator, before mains power could be restored. It was a lot more complicated to put the mains supply back but thats the basics.

So if BR could do it or it wasnt cost effective for them, i cant see it being an option for a boat.

I wont answer a lot of things on this thread as my qualifications are not valid these days as last refresher course i did was early to mid 1980's, but some things said do make me cringe..

Charlie

[BroadScot]

2 minutes ago, Bound2Please said:

British Rail had standby 660v generators for our department

By 660v Charlie I assume it was three phase? If so, that would explain why you had to manually switch it off. 

Iain

[Bound2Please]

Just now, BroadScot said:

By 660v Charlie I assume it was three phase? If so, that would explain why you had to manually switch it off. 

Iain

Yes Iain 3 phase and 83 1/3rd cycles

Charlie

[BroadScot]

Many of those generators were made at the Alan West factory in Ayrshire, as they were used in the local mining industry then.

Iain

[Bound2Please]

we had inverters for the 415 coming in, then it was converted to 83 1/3rd cycles from there transformed to 110v ac, 24v dc , 12v dc, and 1.5v ac and 1.5v dc not just straight forward 220/230v .

Charlie

[grendel]

many years ago during the 1985 hurricane aftermath when I was working for the local electricity board, we had an engineer killed as someone connected up a generator to supply their house while the power was out. unfortunately they did not isolate the supply from the mains supply, and when the engineer was working on the HV side, the generator voltage went through the transformer, was converted to 11,000 volts, which gave him a shock whilst working up a electricity fall. If the shock did not kill him, the fall from the pole certainly did, mixing generators into the supply mains should never be done, unless at a power station equipped to synchronise the phases properly, or by some other qualified electricity supply engineer under very specific circumstances, or after the mains supply has been isolated.

[Bound2Please]

2 minutes ago, BroadScot said:

Many of those generators were made at the Alan West factory in Ayrshire, as they were used in the local mining industry then.

Iain

All ours were westinghouse dynamo's and gardner straight 16 diesel engines

Charlie

[BroadScot]

 

1 minute ago, Bound2Please said:

we had inverters for the 415 coming in, then it was converted to 83 1/3rd cycles from there transformed to 110v ac, 24v dc , 12v dc, and 1.5v ac and 1.5v dc not just straight forward 220/230v .

Charlie

That sounds very similar to the mines 110v dc units.

Iain

[grendel]

One thought, when using an inverter, where is the earth connected? most inverters I know connect to a battery, and supply a standard 13A socket, so where does the earth lead to, is it connected to the neutral in the inverter? - or where.

[TheQ]

sounds

Just now, BroadScot said:

3 minutes ago, Bound2Please said:

we had inverters for the 415 coming in, then it was converted to 83 1/3rd cycles from there transformed to 110v ac, 24v dc , 12v dc, and 1.5v ac and 1.5v dc not just straight forward 220/230v .

Charlie

That sounds very similar to the mines 110v dc units.

And very simlar to the systems we had to produce Aircraft supplies and 400hz

[Bound2Please]

could well be Iain, we had no 110v dc mind only 110ac but all other voltages ac and dc ... 83 1/3 so no interference from stray earth voltages

Charlie

[BroadScot]

3 minutes ago, Bound2Please said:

All ours were westinghouse dynamo's and gardner straight 16 diesel engines

Charlie

What....no Brooks inductions motors lol

[Bound2Please]

2 minutes ago, grendel said:

One thought, when using an inverter, where is the earth connected? most inverters I know connect to a battery, and supply a standard 13A socket, so where does the earth lead to, is it connected to the neutral in the inverter? - or where.

Sorry Grendal Vaughans been asking that all morning but his question gets evaded. Wish you better luck. Sorry cany answer that myself either.

Charlie

[grendel]

I will ask our electrical engineers here at work

 

[BroadScot]

1 minute ago, Bound2Please said:

could well be Iain, we had no 110v dc mind only 110ac but all other voltages ac and dc ... 83 1/3 so no interference from stray earth voltages

Charlie

I had a friend who worked on the overhead installation Ayr to Glasgow, he kindly tried to explain the earthing for the overhead line, very technical, when 11kv I believe is involved ?

Iain

[BroadScot]

9 minutes ago, grendel said:

One thought, when using an inverter, where is the earth connected? most inverters I know connect to a battery, and supply a standard 13A socket, so where does the earth lead to, is it connected to the neutral in the inverter? - or where.

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

Iain

[Bound2Please]

2 minutes ago, BroadScot said:

I had a friend who worked on the overhead installation Ayr to Glasgow, he kindly tried to explain the earthing for the overhead line, very technical, when 11kv I believe is involved ?

Iain

Thats old Iain was 25kv in 87  but yes the earth is refered to as earth return and every stantion is individually earthed to the running rail , but jumping out of the way of 100mph plus trains is a young mans game... now they shut all roads for simple maintenance even

Charlie

[TheQ]

14 minutes ago, grendel said:

One thought, when using an inverter, where is the earth connected? most inverters I know connect to a battery, and supply a standard 13A socket, so where does the earth lead to, is it connected to the neutral in the inverter? - or where.

 the thread just keeps moving rapidly!!!

 

Not evaded

I tried to answer this one on the previous page 5th post up, this is where there is some dispute, as some authorities say your 230V Earth line should be connected to the same line as your Sacrificial Anode, which is also connect on most boats to Negative 12V DC and your engine block. Though as Vaughan pointed out earlier this can lead to other problems.

[Vaughan]

1 hour ago, Vaughan said:

This is comprehensive circuitry but how is it  protected, when the boat is not connected to earth?

Excuse me quoting myself, but there is a reason for this question.

All of Crown Blue Line's modern large boats have 220v plug points all over the boat, so that everyone can plug in all the accessories but in our case, the plug points only become live when the boat is plugged into the bank and therefore earthed to the shore. The only inverter on board is a little "plug in" thing, much like a shaver point, which is there to charge phones, although we always recommend this is done by the 12v cigar lighter socket and we always advise clients, in their paperwork, to bring 12v adaptors with them for this purpose.

But the circuits involved for all the outlets, plus the fridge and the microwave, amount to what you you might find in a small bungalow, and I would certainly expect that to have an earth!

If it is going to find it's earth out through the hull, through the anodes as suggested, then there is going to have to be a lot more thought given to cathodic protection of prop shaft, and sensitive equipment such as the bow thruster.

I don't know whether the electrolytic action of the 12v circuit, as described above, is then going to be made better or worse by also having the AC earth connected to the anodes, as I am not qualified to say, but I don't like the sound of it!

[grendel]

there is usually no earthing on an 11kV overhead line as it is a 3 wire system, the neutral comes from the star point on the step down transformer to 415V 3 phase.

all substation earthing relys on an earth mat at the ends of the cables, if the connection to earth cannot be got down to a certain resistance, the site is referred to as a hot site, when everything metallic must be earthed to a central earth connection, a hot site under fault can have a voltage potential across gaps as small as a few metres, where the earth voltage can be enough to cause injury if the two locations are bridged by a person (eg a metal support and a metal fence adjacent).

[BroadScot]

Oh dear went brain dead Charlie, I was thinking pylon 11kv and as Grendel says no earth. Working on the islands you create the earth by single or tripple copper rods, take your earth from the neutral, and PME the whole building with 10mm earth wire !

7 minutes ago, Vaughan said:

I don't know whether the electrolytic action of the 12v circuit, as described above, is then going to be made better or worse by also having the AC earth connected to the anodes, as I am not qualified to say, but I don't like the sound of it!

Agreed, Vaughan,  it sounds very iffy to me.

Iain