Diesel Generator problem

[P&H-Gas]

Hi all,
I have the use of diesel generator which I hope to use to power lights and bits at my wedding this year.
The down side is that the 240V output has a fault.
The guy I have borrowed it off has told me that if any thing is plugged in, it will trip the breaker.
The 110V will work all day long.
The only othe thing he said is that apparently the connections to the 240V sockets "came off" so he screwed them back in.
All of this is what I have been told about it as I havent done much to test it as yet.
My first thought was a possible earth fault, but having metered between live/earth and neutral/earth, there is no short.
My next thought is that he may have reconnected the live and neutral back to front. Is there any easy way to check this?

The genny is a Kubota Lowboy GL-6500S.

Any help greatly appreciated.

 

[mike 109444]

If you meter the 240 when it's running that won't trip it but will tell you if it is out putting 240? If you don't want to mess around to much with it the see if you can load a 240 to 110 yellow box (builder type) and make up leads to swap around input and out put ie 110 in 240 out! Just take care as you could end up with a 3 pin plug on the output of yellow box that is 240!! hence change 1ST to a socket. Hope that makes sense. ps there are cheep plug in devices that have lights on them to show incorrect live-neutral-earth connections Have one burred away inmy toolbox but very rarely use it.

 

[P&H-Gas]

Cheers Mike, I will check the output tomorrow and see if it is 240V.
Good idea on the yellow box transformer, if the 110 is good, then use it to convert back to 240......simples

 

[the snooper]

check the changeover switch aswell when in 110 volt mode the two coils from the altenator run in paralell but when switched to 240 run in series could be a fault there failing that you will need to check the resistance of both output coils from the altenator to make sure both are good as it will still produce 110v on one coil but the amperage would be down other then that it will be wiring / sockets

 

[P&H-Gas]

Cheers Snoop, I will check the switch and make sure it is switching properly.

 

[P&H-Gas]

forgot to mention that this thing has only done 70 hours of work according to the clock so I am guessing that the fault is unlikely to be caused by wear and tear on any parts... or is that just a silly assumption?

 

[piman]

Hello P&H,

"Good idea on the yellow box transformer, if the 110 is good, then use it to convert back to 240......simples "

I'm not that familiar with small self contained generators, but if the output is earthed to the chassis somewhere (and the sockets also); site transformer's 110 side are centre tapped earth so you may burn out the transformer winding as it will have a 55v coil fed with 110 volts from the generator, also you could have much more than 240v on the other side? Check how the generator is wired very carefully first.

Alec

 

[Robotstar5]

I'm not that familiar with small self contained generators, but if the output is earthed to the chassis somewhere (and the sockets also); site transformer's 110 side are centre tapped earth so you may burn out the transformer winding as it will have a 55v coil fed with 110 volts from the generator, also you could have much more than 240v on the other side? Check how the generator is wired very carefully first.

A lot of small generators (up to 10kVA) have a "floating earth" the earth connection on the socket(s) is connected to the chassis/frame but there is no reference from the windings of neutral to earth.

 

[madkayaker]

What bit is tripping? is a overload or a RCD? It's possible the RCD needs a earth spike

 

[piman]

Hello Robotstar,

if there is no earth reference to the windings, what happens if there is an earth fault in the generator or an item fed from it?

Alec

 

[brightspark]

http://www.voltimum.co.uk/news/6514/s/Small-generators-on-construction-sites.html this wiil explain all and any other technical details required

 

[Robotstar5]

Hello Robotstar,

if there is no earth reference to the windings, what happens if there is an earth fault in the generator or an item fed from it?

Alec

Good point, it had me scratching my head when wiring the stables to run off a generator.

The regs state should only be used to supply one item of class I equipment and/or one or more items of class II equipment.

 

[P&H-Gas]

Thanks for all the replies, I didn't get chance to test the genny this weekend as I was busy building an arch to stand under on the big day. I think once I have established if there is 240 coming out of the sockets, and there are no obvious dodgy connections inside, I wil hand it over to a specialist to sort. I really dont want any complications on the day.
Is there any where I could get a wiring diagram just to check that the live and neutral are connected correctly?