Hi Mark,
Sorry to be a little late in replying.
I was not expecting an answer tonight, its three in the morning here (UK).
I realise that electrics is not your field, so i will try to be direct and
clear, and i will try not to be misleading in anything i may write.
As there have been over a hundred and fifty views on this thread, i am sure
that somebody will soon speak up if anything looks confusing.
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Does running the generator restore any of the residue magnetism?
.
There are differing opinions on this.
Some say it does.
I dont think it does,
but i do think that striking or hitting metal while its being magnetised
can cause it to retain some magnetism.
So if the unit were knocked or dropped or struck in some way while the field
windings were energised, then maybe that would account for some people who
say that running it helped it retain some magnetism.
I have never known running a generator to help with residue magnetism.
The only (sensible) way i know of to impart magnetism to the field poles
is a couple of short sharp pulses of high current through the field windings.
I dont think running it will help at all with the residue magnetism.
(
this is not a suggestion to knock or strike the unit in any way)
The Flashing.
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This is not something that will need to be done often.
Many generators will retain their residue magnetism for years.
The coils are copper and do not retain any magnetism, it is the ferrous metalwork
that retains the residue magnetism, that is - the pole pieces of the field assy.
The flash or spark is due to the sudden interruption of the current which is
temporarily applied to the field winding/s, usually by a person touching it's
connection with the tip of a length of wire.
This is a function of the inductance of the winding, and is not associated with
a capacitor in any way, other than maybe their shared connection.
Having the capacitor involved by remaining connected can only reduce the desired
effect of flashing the field winding.
I was shown to 'flick' the temporary connection off of the terminal which resulted
in a distinct flash as the wire 'sprung' away from the terminal.
This seems dificult to describe, but very easy to do.
I would hold the wire on the terminal or connector near it's edge, then push it
past the edge in a flicking motion, so that it would break contact while moving
quickly. This would usually give a disinct flash.
It only needs to be done a couple of times.
The residue magnetism is needed only for the starting up of the generators
electrics, once its running the field would be fed in some other way from the
unit's output.
If the unit started to fail when it was running, then this could be as you say,
the rings getting a bit gummy with oil.
It would be best not to have the capacitor or the diodes conected to the field
while flashing as they could be damaged quite easily by it.
Those sort of sparks and voltages wil not do the capacitor or the diodes any
good at all.
Best of luck with the petrol leak and the mixture settings,
John