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Another stupid question about converting from single phase 120v to single phase 240v!


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  #1  
Old 01-25-2011, 02:31:06 PM
Patrick Patrick is offline
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Default Another stupid question about converting from single phase 120v to single phase 240v!

Another shabby 3.5CCK has fallen into my hands. It only runs on one cylinder due to a badly bent or displaced valve on the inlet side, but I thought I would leave that for another annoying day, as the garage is very dark and I've never dismantled the valvegear on one of these. Though any thoughts would be appreciated - it's so bent or "out of place" over to one side that I can see the entire width of the valve seat. on the other side. No marks on the head or valve.
It's a 120/240v unit. No diagram inside the control box, but the circuit board housed within looks like this if that's any help -



The ever valuable tag info -

3.5CCK CR/8886J
SERIAL - 047122011
Standby 3.5kVa, etc, P.F (Phase Factor?) 1

As you can see, the wiring is unlabelled, and as I said there is no diagram - it's an ex-army unit, and I don't think they wanted squaddie amateur electricians trying to change the voltage!

Would any of the gurus or otherwise be able to help out?
It does happily produce 120v, and even if I don't get round to fixing the valve for a few weeks I think I should be fine running on one pot until I fix it - my electricity bill is so low that the electric company came out to test the meter. About 4 18w CFL lights, the boiler and a couple of small pumps, and my laptop are all that are normally on. Obviously I'm not going to try and use my electric oven!

Cheers,

Patrick.
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  #2  
Old 01-25-2011, 03:33:30 PM
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ListerDiesel ListerDiesel is offline
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Default Re: Another stupid question about converting from single phase 120v to single phase 2

'Normally' there would be four wires from two windings, and you would parallel the (correct) pairs for 110V and then series the correct pairs for 240V.

A - B 110V Winding 1
C - D 110V Winding 2

Connect A & C and B & D for full output at 110V.

OR

Connect B & C and take 240V from A and D.

You must identify the start and finish correctly, or you'll do some damage if the 110V pairs are paralleled incorrectly, or get almost nothing out if the series connection is wrong.

A and C are the Start and B & D are the Finsih of the windings.

That's the basics, your own unit may be different now I have said that!

Peter

PS: Our Ex-Rosyth CCK is still sitting in the workshop, haven't run the darn thing yet!
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Old 01-25-2011, 04:06:56 PM
Patrick Patrick is offline
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Default Re: Another stupid question about converting from single phase 120v to single phase 2

That's normal Peter, I mean you've only had the BRAND NEW GENERATOR for about 3 years now? Who would expect it to be fired up in that time!?
I have absolutely no idea which wires I am supposed to parallel/series - as you know, I'm fine with the spinny stuff but not so good at the sparky stuff!
PS - did you see the old water-cooled Onan on Ebay recently? Think it's gone now, you probably have it!

Oh look, it's still there... http://ebay.co.uk/Onan-Generator-W3m-/220729053171

Last edited by Patrick; 01-25-2011 at 04:14:07 PM.
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Old 01-25-2011, 06:15:18 PM
Kimbra Dean Kimbra Dean is offline
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Default Re: Another stupid question about converting from single phase 120v to single phase 2

Terminal strip in lower lefthand corner of your picture. 1 & 2 should be one winding and 3 & 4 should be the other winding. Terminal 2 may be bonded to the frame.

For 120V connect 1 to 3 and 2 to 4. Terminals 1 & 3 will be the hot leg and 2 & 4 will be the netural (Assuming 2 is bonded to the frame). Kind of hard to tell but looks like the output wires are connected to 2 & 3 now.

For 120/240 Connect 2 to 3. Terminals 1 and 4 will be the 2 hot legs and the 2&3 connection will be the netural.

For 240V only (which I suspect is what you want) connect 1 to 4. Terminal 3 will be hot and 2 will be netural.

Check your current connection and see if it is wired as I described for 120V. Also check to see if terminal 2 is bonded to the frame. It may be bonded at the brush holder. If so then you can be fairly confident that the other two voltage connections I have given you will be correct.

Be sure to remove the connections between 1 & 3 and 2 & 4 before jumpering any other terminals together.
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Old 01-25-2011, 06:32:45 PM
Dave Edmonds Dave Edmonds is offline
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Smile Re: Another stupid question about converting from single phase 120v to single phase 2

Most of the wiring appears to have been replaced, except the wires coming out of the genend and connecting to the terminal strip referred to in the previous post. Those wires should still be labelled with the M1 - M4, T1 - T4, 1-4, or whatever Onan happened to be using at the time of manufacture. There appears to be wires leaving the generator from those terminals, probably going to voltmeters, hourmeters, receptacles, etc. You may need to find out where they go before disconnecting anything. It also appears that the jumpers used to connect the two windings in parallel may be a case of "a long wire for a short distance" - some of the wires are difficult to see where they go. In any instance, all of the above advice is correct - you have two 120-volt windings; they connect in parallel for 120 volts, and in series for 240 volts. It's not a lot of help when someone removes all the well-marked wiring that was probably in there initially, and replaced it with a bunch of white wires that aren't labeled! Not too hard to figure out, though.
Dave Edmonds
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Old 01-26-2011, 09:19:03 AM
Patrick Patrick is offline
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Default Re: Another stupid question about converting from single phase 120v to single phase 2

That's great, thanks all!
Yep, I thought it looked as though it had been rewired - oddly enough I have another one for spares only, with the same white wires and crimps. Maybe these were also reconditioned the way my "best" one is, and they just used white wire - I haven't looked under the cover of that one yet because it's down at the cabin and was already wired for 240v!
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Old 11-29-2011, 04:15:01 AM
LiverpoolDave LiverpoolDave is offline
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Default Re: Another stupid question about converting from single phase 120v to single phase 2

By now you have probably already got her running or sold her by now but anyway, one small thing, you could well be right about bent valve but bear in mind it could just be 1) sticking in it's guide due to lack of use-rust-gumming (WD40 & visual checking through rectangular access ways on top). 2) have lumps of carbon preventing it from seating-sealing correctly (had this on 2 cars an easy fix) or 3) maybe the valve clearance adjustment has been set too tight by a past owner. You may still have to remove a Cylinder Head valve to be sure, but may not need any parts other than a head gasket, hope it helps from over the 'river' .

If you have the head off it & is obviously IS 100% bent then it has been over revved, strange as they cannot touch the pistons on these just (possibly) the cylinder head cavity. A mail order valve from Cummin's in USA or new-old UK stock could be available often £7 or more for a much larger car variant. Be sure to quote model & serial numbers off the plate, but makers rarely change valve types unless on a re design or facelift.

Maybe some helpful member could open your photo in 'paint' and label a b c & tell you where they go, I can connect alternator windings up in series or parallel with effort, but I usually test with digital multimeter to figure out what has to go where, momentary miss connection results in a spark or engine stall (which you can get away with) but screwing them down when unsure!! smoking stators may result.

By the way Patrick these Onan CCK's run like a dream on Bottled Propane gas (if available where you are) most reckon it's around 40-50% the running costs, message me & can tell you how to do it cheaply, for about £10-£12 plus bottle , all the best

Dave.
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Old 11-30-2011, 02:08:16 PM
Patrick Patrick is offline
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Default Re: Another stupid question about converting from single phase 120v to single phase 2

Cheers Dave! The genny runs on petrol as it's easier to bring over to the island the genny is on, on Loch Erne - the fridge and cooker already run on gas, the sole reason I brought this over to the island is to use an immersion heater - no other way of getting hot water!
The cabin is RIGHT on the lake, actually on stilts, so soggy land is a problem which meant we had to bin the old Raeburn (it was a complete whore to light, anyway!) as the kitchen began to fall away from the rest of the house.
Sometimes new people beaatch about the cost of filling a couple of 20l jerry cans - but not when it's cold outside, and they have a remote switch in each bedroom to fire up the genny and heat the water before they crawl out of their beds!
Oh - I have a few CCKs, this was just one - bought another two for spares, for £50 - the one with the bent valve now lives in my garage, fixed from a spares unit - the other spares one mostly lives in my shin, when the power goes out. I could buy a torch, bit they are so expensive!
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