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Author Topic: Guidance needed  (Read 10281 times)
« Reply #15 on: June 30, 2010, 03:10:39 PM »

(The L1, L2 circuit is obviously the 230v generating circuit so I know what to do with that.)
Measure the insulation resistance between  L1 and frame, then L1 and commutator. Measure shunt winding to frame. If less than 1 meg drying is recommended.
(The unmarked circuit has to be the exciter circuit with perhaps a secondary function but what exactly?)
Battery charging. Optional.
(Ken suggested it may be a starter to start the engine, but when connected to a battery it tries to turn the wrong way so it would appear in cannot be a starter!)
Ken is correct to assume that an alternator having a DC commutator has starting capability. Why go to the trouble of a commutator when there are other simple lower cost methods of providing excitation? No Diodes to fail.
From the info provided this alternator does not appear built for engine starting.
(So what to do with this unmarked circuit?)
Using a rheostat, at a guess say 5 ohm 150W. Run up to speed and adjust to obtain desired no load voltage.
(Connect the two wires together to complete the circuit then drive generator with engine to see if it will produce current ?!)  
Yes, as a test to see if the alternator works the way I am guessing it should. Increase the speed gradually to build up AC voltage with a current clamp on the shorted wires so as not to exceed the name plate shunt current of 12A. No load rated voltage should be reached well below rated speed.
(Isolate and insulate each wire  then drive generator to see if current is produced ?!)
Yes, this should result in residual open circuit L1 L2 AC voltage, together with a DC voltage across the shunt and armature winding.
(What else ?!)
Have a good look inside the frame for any terminations or wires that have been cut or taped up. Although I am not familiar with this particular set, I would consider the possibility of an auxiliary field compound winding to provide regulation under load.
(The object of the exercise is to have a functioning generator so I don't want to do anything that will ruin it !)
Part of the fun, I enjoy "terminating" the old'uns, get the chance to sell a new one!
(Another question is, of the two unmarked wires which should be regarded as the positive the one that goes direct to a brush on the commutator or the one that goes direct to the field windings?)
Spin the alternator and use a DC voltmeter across the brushes to find out.
It can be connected either way, Edit; the shunt winding linked to it's trimming rheostat are in parallel with the DC armature, the tails out to the rheostat can be from either side of the shunt winding. Direction is changed by swapping over the DC commutator connections. As you have already found, swapping polarity across the shunt and DC armature makes no change to rotation.
How to provide regulation under load? See if it survives the above tests first.

Edit. Amended sentence to remove the word "series" in circuit connection.
« Last Edit: July 01, 2010, 10:43:52 AM by ecogen » Logged
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« Reply #16 on: June 30, 2010, 04:39:32 PM »

Ecogen many thanks for your very useful reply.
As I am not a sparky of any description, merely a very cautious bodger and don't have the equipment to carry out all the tests you are suggesting, I shall have to consider very carefully what I can attempt with my little meter which is restricted to measuring AC and DC voltage, resistance, and circuit continuity.
I was considering e-mailing Stationary Engine Parts Ltd to see if any of the AVRs that they stock for Lister equipment would be suitable for this generator(as Ken said that BKB supplied Lister at one time) and provide a simple way of getting the generator up and running(subject to cost). Looking at the circuit diagrams on the Lister_CSOG forum it looks as if the actual shunt would be in the AVR control box not within the generator itself but I will have another look at the generator.
I think I am making some progress if only in terms of knowledge!
Thanks again,


200w wind turbine grid tied, 1x175w PV grid tie or to batteries,
2x55w PV to batteries, 24vx440ah battery bank. 3.5Kw grid tie (14xSanyo 250w facing 160degrees at 80 degrees inclination, Aurora 3.6 inverter), 2xflat panel water heating (for over 30 years )
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« Reply #17 on: July 02, 2010, 02:08:15 PM »

Following on from Ecogen's posting I have carried out as thorough an inspection of the generator as I can.
Attached is a rough diagram of the layout viewed from the commutator end.
As seen the field coils are in two bundles, one on either side of the rotor, in the casing.
The commutator has four brushes arranged in two linked pairs one pair each side of the commutator.
The field coils and commutator are wired in series such that one connection wire goes to one field coil pack and the second connection wire returns from one pair of brushes on the commutator(or vice versa).
There are two slip rings one for L1 and one for L2.
There are no visible signs of any other wires or parts within the generator.
I don't know whether this throws any more light on the intended set up, if so please advise.


* GenPlan.gif (12.77 KB, 719x1048 - viewed 502 times.)

200w wind turbine grid tied, 1x175w PV grid tie or to batteries,
2x55w PV to batteries, 24vx440ah battery bank. 3.5Kw grid tie (14xSanyo 250w facing 160degrees at 80 degrees inclination, Aurora 3.6 inverter), 2xflat panel water heating (for over 30 years )
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