Any generator experts?

[Matchless]

I obtained a Pramac 6kva diesel generator for home use in power cuts, wired in a change over switch etc. today then found that I have only 210v output at 53Hz but more worrying is I have 93v between live and earth and between neutral and earth, I did not connect it to the house!
The generator has had a hard life as I got it as a non runner, it had broken piston rings and ring lands, several people had messed with it trying to get it running and I had most of it apart to rebuild the engine.
I have no idea if it worked properly before it broke down.

Any ideas on what is wrong? electricery is not realy my cup of tea!

 

[addjunkie]

@GRW is your man if my memory isnt gone!

 

[Guineafowl]

I found Pramac UK were very helpful with stock wiring diagrams and such, when I was doing up the electrical side of one of their 30kVA 3 phase generators. It had been cocked around with, so I rewired everything to factory setup.

Standard setup for multiple earthed appliances, or to a house would be an earth stake to genny and bond neutral and earth within, effectively a TNS supply. Consult diagrams and/or electrician if not sure, though!

 

[maroon]

google "center tapped generators"

 

[gaz1]

looks like yours is the p6000 model

 

[GRW]

Yes, it's a P6000. 6kva, 4.8kw, with a 10Hp Yanmar L100 1-cyl engine.
Not certain what alternator, but it's a high chance it's a Meccalte brand.

I'm pretty sure those were a Capacitor controlled alternator, so I'd head straight to measuring the microfarad reading of the Capacitor against it's stated rating on the case.... chances are (as you've not "lost" too many volts) that the Cap has aged and is reading lower than it should.
If so, then a new Cap should restore voltage where it should be.
Note that with Cap regulated sets the voltage increases with rpms/Frequency, so at 210v at 53hz you'd expect it to be much more like 230-240v (off-load at 53Hz is fine tho btw).
Dual voltage sets tend to have a "floating voltage" as the c/o arrangement means that as std Neutral & Earth aren't linked - so your odd readings and a voltage between N & E is quite likely due to this and not a "fault" as such. (Designed to run power tools and not House Dis Boards with RCD's - and the power tools don't care about the floating voltage).
You could dispense with the 110v sockets & c/o - and connect just for 230V, and then add a N-E link in the alternator (or add a link wire in the back of the 230v socket which does the same thing). This will get rid of the floating voltage between N&E, and eliminate possible nuisance tripping of the house RCD.

 

[Matchless]

There is a big (4" tall, 2" dia) capacitor behind the panel, I will try to work out if I can test it, what would be involved in dispensing with the 110v sockets etc.?
Interestingly the no load voltage on the 110v sockets is 120v,

 

[GRW]

There is a big (4" tall, 2" dia) capacitor behind the panel, I will try to work out if I can test it, what would be involved in dispensing with the 110v sockets etc.?
Interestingly the no load voltage on the 110v sockets is 120v,

If you have a multimeter with the feature, you can measure capacitance (but not all do - esp. the very cheap ones).
The fact that the voltage is 120v on the 110 side is intriguing! It suggests the Cap is fine - so I'd be wondering if there was a poor joint or connection in the socket.... work your way back to see if the voltage is 240vac off the alternator. It could be that one of the 2 windings is iffy.... but I'd say its more likely the changeover toggle switch contacts are iffy, and not making good contact.
As for removing the 110v... well you can just remove the wiring to the yellow sockets ( & tape off the wiring safely), or remove and blank off altogether.
As long as you maintain a direct 240vac supply to the blue sockets bypassing the c/o switch completely, you shouldn't be able to get it wrong (& you have the existing arrangement to meter out so you can confirm exactly which wires give 240v into the changeover switch, and which ones exit the c/o switch to supply the 230vac socket.

 

[Justme]

Had a few of them.
Low voltage is the capacitor.
You want a 35mf 400v. Pref a motor run type.
For free standing use having a floating voltage is normal.
For house use bond N and E together.

 

[Matchless]

Had a few of them.
Low voltage is the capacitor.
You want a 35mf 400v. Pref a motor run type.
For free standing use having a floating voltage is normal.
For house use bond N and E together.

Is this the one? eBay item number:322454431745 I had already installed a copper ground spike earth,

 

[Matrixx]

You don't want floating voltages in a domestic application, I would make sure the neutral is earthed in the alternator, there should be a neutral earth point. Then check the voltages . 53 Hz is usually the mechanical droop, so would be 50.5 Hz at full load.

 

[Matchless]

You don't want floating voltages in a domestic application, I would make sure the neutral is earthed in the alternator, there should be a neutral earth point. Then check the voltages . 53 Hz is usually the mechanical droop, so would be 50.5 Hz at full load.

It is a major strip down to get to the alternator, can I earth the neutral behind the sockets?

 

[GRW]

It is a major strip down to get to the alternator, can I earth the neutral behind the sockets?

Yes you can as I posted earlier - does the same job.
The reason I suggested belling through / metering together your 1ph 230v supply directly connected and bypassing the changeover (as prev post also) is that the 6-pin c/o switches used I think may preclude the ability to N-E link with it in circuit.
If you ever wanted to run a 110v tool off the genny - its far safer to run a 110v CTE Safety Transformer off the 230v outlet anyway

 

[Justme]

Is this the one? eBay item number:322454431745 I had already installed a copper ground spike earth,

Yes but you can get cheaper than that.
From memory CBB60
Join the N and E in the control panel.

 

[dobbslc]

You don't want floating voltages in a domestic application, I would make sure the neutral is earthed in the alternator, there should be a neutral earth point. Then check the voltages . 53 Hz is usually the mechanical droop, so would be 50.5 Hz at full load.

This thread has got me thinking about the generator I have and use when there's a power cut!
I haven't tested between neutral and earth to see what voltage there is. I've had no trouble with RCD 's tripping though.

 

[GRW]

This thread has got me thinking about the generator I have and use when there's a power cut!
I haven't tested between neutral and earth to see what voltage there is. I've had no trouble with RCD 's tripping though.

If you've had no issues, I'd say there's no need to be concerned about it. Small 3000rpm 230v/110v portable sets tend to have a floating voltage, but anything a bit more "industrial" is almost certain to have a N-E Link.

 

[dobbslc]

It's a 2kva Generac set so only a small one! I'll check it next time I fire it up as I don't want to fry my central heating controls

 

[Justme]

This thread has got me thinking about the generator I have and use when there's a power cut!
I haven't tested between neutral and earth to see what voltage there is. I've had no trouble with RCD 's tripping though.

The issue is they dont trip when needed.

 

[dobbslc]

I've recently been reading about DC blinding of some types of RCD. It's quite in depth and there's a lot of info I didn't know but it could be helpful at work as a reason we get earth leakage faults jumping the smaller RCDs and tripping other up stream.
I'll fire up the genny and test it if I get a chance