Need advice on old Gen

[BigMal]

Hello to the Group, I am a Newbie just getting his feet wet with a Lister 6/1 and old generator, I wonder if anyone can identify this old generator, and tell me if it is capable of starting the lister, as it has a 4 brush commutator. But I am unsure as to whether it is solely for exciting or for driving? I also notice that the KVA plate has been overstamped by the look of it. I think it should read 3.5 not 5.5  Also the wiring connections are not exactly obvious!!! Any help would be gratefully received. The pictures are on http://goldvale.com/gen.htm

Thanks

Malcolm (based in the UK)

[Doug]

Hello Malcom:

What you have is a syncronous converter but it was intended to be a driven alternator!!!!
This is very exciting stuff!!!!
You have found the holy grail of DIY alternator heads. This will easily start a 6/1, however it will need a good cleaning and once over. The whole unit should be taken down and cleaned with an electrical grade solvent, ( the windings look good but no harm in a fresh coat of electrical finish or varnish ) and the packing and wicks should be removed from the bushings and replaced new and reoiled with a non detergent # 30 oil.

As far as the connections go this is very hard to tell from pictures but you should have 6 wires (and it apears you do) two for the AC out, two for field current (the small red ones) and two for the dc to motorize this unit. It also looks like there may be an interpole connection on this that you need to be aware of for rotation purposes but I can't be sure without taking it apart.

As far as the restamped nameplate goes this was and is common practice when rewinding older units like this. Often at the rewind works they use a higher temp insulation material that allows older machines designed with all organic insualtion systems to produce anywhere from 20-30% more power depending on the mechanical strength of the bearings.

Thats arealy nice looking alternator, but you are missing some for the inspection covers to funnel cooling air threw the stator.

Doug

[BigMal]

Thanks Doug for your reply, it is nice to find someone that has an in depth knowledge of these things, a couple of questions - what is a syncronous converter? I have a little electrical/electronic experience, but work on the basis I'm a DUMMY - it would probably be safer.
Does it mean it was a DC to AC converter? (I think they used to call it a transverter) Also what are wicks and packings, does a wick feed oil into the bearings?.... I would be happy to strip and refurbish but I need a little guidance about what to do on a step by step basis so that I dont muck it up. When you say revarnish do you mean giving the windings as a lump a revarnish or should they be rewound and then varnished?

Malcolm

[Doug]

Well Malcom the best way to see this head brought back is to load on a ship to Nother Ontario Canada And I'll give it a good home ( Just kidding, but I wish I had that retro hardware )....

The wicks I discribed are exactly as you pictured, to get the right material take the old wick and stuffing out and bring it into a motor shop they will sell you something to make a wick from or a prefab wick that fits. The stuffing is probably just cotton waste and the new material you will purchase will look loke a roll of untwisted wool yarn.

And yes this machine can convert DC to AC power, both the commutator and the slip rings are interconnected to a common set of windings in the armature. In practice the DC winding is only used for starting but before mercury arc valves were used to rectify AC to DC large poly phase machines with this type of interconnected windings were used in industry, infact this worked so well some of these machines are still in service on my side of the pond 75 years after they were built. I would have set your machine up on a test rig to see exactly what it can do, but I suspect it should be able to charge your batteries as well as start your 6/1, perhaps it might even draw power from the batteries to supliment the Lister in a heavy surge ( Like I said I would need to test and play with it )....

As far as the varnish goes if you look inside the machine you will notice what looks like a semi gloss red oxide paint finish. This is not a primer but an electrical varnish used to supliment the original varnish durring an overhaul at some time in the last 25 or so years. Most air dry varnishes/electrical finnish are this colour when sprayed, brushed on or pour though varnishes are clear or amber. Baked on varnishes are also general clear or amber too.

This looks like its seen a lot of service by the carbon dust inside, it should be cleaned, but nothing in the pictures leads me to think this needs any real work provided the bushing are good,  and the com and slip rigs are true.

Doug

You have something special here, I wish the indians had also cloned these along with the Listers....

[GuyFawkes]

just seen this thread

that looks a lot like the "other" type of gen head fitted to startomatics, if so it will start the diesel by drawing 24vdc, and provide 24vdc as well as 240vac while being driven.

ElectroDynamic Ltd are, I am 99% sure, still trading, so they would be your best bet for info.

http://www.companieshouse.gov.uk/

[Doug]

There is a Company in France that still makes something like this but there simply to expensive to build for anything less than millitary ap that need to be raditaion hardened.

I can't rememeber the company's name......

Doug

[BigMal]

Thank you for all your advice, how efficient would the converter side be in 24v dc to 230v ac? Could you use that ability to run from a battery bank instead of using an inverter, and when the batteries begin to run down autostart the lister? Just looking at the possibilities......

Malcolm

[BigMal]

Quick thank you to Guy Fawkes, found the company address in Loughborough, but they appear to have disappeared off the face of the earth, nobody at that address has heard of them??? Wll keep trying..

Malcolm

[EVguru]

I've got a very similar Generator head (http://www.powercubes.com/listers_3.html), mine is rated 2.5KVA.

If it's the same principal as mine it's a static field alternator combined with a DC motor. There would be three field windings; A main field, and auxillary field for trimming the output voltage, and a series field to provide high torque for starting. The series field uses the main case as one of the connections.

Guy has a copy of the manual on his website; http://www.surfbaud.co.uk/Lister/Files/lister%20s-o-m%20manual.pdf

[solarguy]

DC to AC efficiency would not be great.  If you make 50% I'd be ecstatic.  Perhaps others could make a more educated guess.

Finest regards,

troy

[Doug]

Malcom:

I can't put a number on the efficiency, but my guess is between 50% and 60% for something this small.....

Many years ago here in Canada when the Onan gensets used this type of head many people discovered these could provide up to 10% more power than the engine could produce stand alone by feeding DC back threw the DC commutator froma source like the alternator on truck in the case of a mobile installation.

Personaly given the chance I would hook this up to a battery bank feed by a windmill or other source to use as a load dump and see if this would reduce fuel consumption.

Doug

[BigMal]

Hang on a minute my brain just melted, run that by me again Doug, please remember the DUMMY scenario, are you saying this is a good way to go, or am I pushing sh1t uphill... especially when you said that it could produce 10% more power than the engine could produce by using a dc feedback??? I think I need pictures drawing, I am an old fart (58) with decreasing brain capacity, please make allowances.. what is a load dump?

Malcolm

[Doug]

Sorry Malcom:

A dump load used in off grid wind mills is a load you dump power you can't use into beacuse your batteries are charged Usualy people use heaters or other resistive loads.

And that 110% thing works like this the dc part acts like an electric motor helping the diesel engine turn the armature are the voltage dips under heavy load provided the suplimental DC is at a little higher voltage than the terminal voltage of the " Machines" ( your alternator ).

Math and mental gymnastics time here:

A Dc motor and a dynamo are the same machine. The difference is when you spin a dynamo you spin it fast enough that it tries to raise the voltage of the system its connected too or to dump amps into a load untill it suplies enough power to ballance out Lenzes law that states voltage is a function of lines of flux cut by a conductor at such and such speed ( dumbed down version but you get the drift? )
When you load down a DC motor you reduce its speed therfore the reverse happens extra current flows into the machine to creat more magnetic field and torque to try and spin it faster and find the ballance point where the speed of rotation is high enough to ballance out Lenzez's law.
This is why motors draw their highest current when they start, there is no rotation of the copper windings to act sort of like a generator and apose the flow of current.

Clear as mud?

Doug

[BigMal]

I would like to thank you all for your help, especially Doug, I will now go and lay down in a darkened room and try and get a grip of all this . I will let you know how I get on.

regards to all

Malcolm

[Doug]

I'd realy love to set up a webcam, black board, work bench full of machines and or better yet a labvolt trainer.
The math can be difficult, but what most of you realy need is just a primer on how rotating electrical machines work, 95% of all service is touch and feel no pocket calculators required.

I don't have the golden hands anymore, but there was a time when I could feel the clearance on bearing in a fully assembled machine a judge the fit ( That is I could rock the shaft on large motor and tell the difference between a C3 bearing fit and abnormal wear in a shaft or housing )....
I could listen to the hum a of machine and tell if it had a good winding or a hack job somebody done.
Now I'm not so sure, but you can tell almost as much from touch and feel and you can from the most expensive surge comparison tester or micrometer. If you focus on your machines and get to know them they will tell you where the problems are.

Doug