How to flash an AC generator
Chuck Jurgens
occasion to use it in the past 4 years. Started it up the other day and the
engine ran fine but the generator won't produce power. It was working fine
when I last used it.
I was told that it needed to be flashed. Can anyone tell me how to do that?
Thanks,
Chuck
Michael A. Terrell
Do you have the owners manual? It should describe how to do it.
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
nni/g...@nni.com
be flashed in the first place?
The rotation iron always magnitized in the same direction so what even could
cause it to lost its residual magnitism to the point where it can't
"bootstrap" up from near zero but NOT zero magnetism?
EMWTK
Anthony Matonak
> This begs the question as to WHY a previously working genertor would need to
> be flashed in the first place?
The residual magnetism in the iron will weaken over time. After a few
years it can be too weak to bootstrap the generator.
Anthony
Hugemoth
Get to the brushes and disconnect them from the circuit board or
rectifier. Connect jumper leads to a 12V battery then connect them to
the brushes for a few seconds. Polarity doesn't matter. That's all there
is to it.
Q
T. Keating
While the generator is NOT running.
Temporarily (~10secs) connect up a charged 12V battery to one of the
110v outputs.
Disconnect battery and start generator..
Nick Hull
Hugemoth <huge...@access4less.net> wrote:
> Get to the brushes and disconnect them from the circuit board or
> rectifier. Connect jumper leads to a 12V battery then connect them to
> the brushes for a few seconds. Polarity doesn't matter. That's all there
> is to it.
What works for me is a special connector attached to the brushes,
with a 1 amp diode in series. If the alternator doesn't produce
power at startup I plug the starting battery (12 volt) in for a
few seconds.
Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/
T. Keating
wrote:
Forgot one step.
After it's started, connect a resistive load, like a pair of 110v
incandescence light bulbs, to the unit as you bring the genny up to
speed & freq.
wmbjk...@citlink.net
<jur...@bellsouth.net> wrote:
This method http://www.perr.com/tip16.html is supposed to work. Easy
enough to try.
Wayne
Martin E
The owners manual typically will describe the procedure.
The last gen that I flashed was a industrial 50hz 3kw motorized generator. I
disconnected the field and fed 12vdc into the field windings. As long as the
field core is slightly magnetized it will be enough to get the stator to
produce enough voltage to get the exciter going.
Cheers
"Chuck Jurgens" <jur...@bellsouth.net> wrote in message
news:13bubfr...@corp.supernews.com...
Neon John
Get a 12 volt battery, use the one in your car or use a battery charger if you have
one with sufficient current capability. Open up the connection box on the generator
and find the leads coming from the stator. These connect to the outlets. Disconnect
them from any other wiring and momentarily connect them to the 12 volts. Simply
brushing the wire from the battery against the generator wire will be enough.
Reconnect the stator wires and crank.
This pulse of current re-establishes the residual magnetism necessary to bring the
generator up when started. This magnetism can go away over time.
If the above "static flash" doesn't work then do a "dynamic flash". Connect a "Jesus
cord" (plug on one end, alligator clips on the other) to the outlet on the generator.
Connect a 100 watt 120 volt bulb in series with the hot leg. Apply the 12 volts
between the bulb and the neutral of the line. The instant the DC current flows, the
generator will start generating 120 volts AC. The bulb is to prevent much AC current
from being applied to the battery. The bulb should light instantly and remain lit as
long as the battery is connected.
If this doesn't work and if your generator has slip rings and brushes then the next
step is to see if the brushes are stuck in their holders and/or the slip rings are
glazed over, preventing the rotor field from being energized. At this point you
really do need the manual to assist with locating the brushes and accessing them.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Okay, okay, I'll take it back ... UNfuck you!
Ulysses
Before you flash it try prodding the throttle and see if some increased RPMs
will get it going.
I've done it with a 6 volt 5 Ah battery with success. I just connect one
side of the battery to the AC output and while the engine is running
momentarily connect the other side. Once the AC voltage starts to climb I
disconnect the battery. You might want to put a fuse in line with the
battery so you don't blow it up. Then run it for a while with a load (like
someone else said).
I've not done it sucessfully with the generator not running. It sounds
safer but had no effect on my particular genny.
Classic-Car-World Ltd
recommendations to no avail. I have a small 3KW generator attached to a
Honda G200 petrol engine. I've had several problems with the engine but have
resolved these and it is running fine. My problem now is that I have no
output from the generator. I'm not sure how long the generator has been
stood without any use and suspect it is simply a matter of flashing it
again.
I've con checked the stator with a DVM and the windings seem to be intact as
are the windings in the rotor.
The unit is a dual 110V / 220V output and the stator has two separate
windings which via a switch and are either used in parallel for 110V or in
series for the 220V output. There is also a 10uf capacitor in the circuit
but I'm not sure where this connects?
The rotor would also appear to have two separate windings with what looks to
be a diode in series with each winding. Unfortunately I can't tell from the
markings on these to confirm if these are indeed diodes.. I also assume the
rotor is self exciting based on residual magnetism?
Would anyone have a circuit diagram of a typical generator set up as this or
provide me with a description as to the principles of how self exciting
rotors work.
Many thanks
Kindest Regards
Tom
<wmbjk...@citlink.net> wrote in message
news:v8n0c3hdi54o9gfbo...@4ax.com...
Neon John
<enqu...@classic-car-world.co.uk> wrote:
>The rotor would also appear to have two separate windings with what looks to
>be a diode in series with each winding. Unfortunately I can't tell from the
>markings on these to confirm if these are indeed diodes.. I also assume the
>rotor is self exciting based on residual magnetism?
>
>Would anyone have a circuit diagram of a typical generator set up as this or
>provide me with a description as to the principles of how self exciting
>rotors work.
This is known as a harmonically excited generator. I wrote a detailed article on how
these work probably not more than 2 weeks ago. It helps to use the archives and
Google Groups.
I'd look at the cap and the diodes in that order.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
What do you call a blonde's dildo? Pneumatic tool.
Classic-Car-World Ltd
"Diagnosing a generator problem - HELP!" after searching on your name.
Can you tell me how the capacitor is connected in the stator please? I'm
assuming it's in parallel with one of the stator coils and forms a tuned
circuit to govern the output frequency?
--
Kindest Regards
Tom
"Neon John" <n...@never.com> wrote in message
news:0npdn35jl6ojb5102...@4ax.com...
Neon John
<enqu...@classic-car-world.co.uk> wrote:
>Thanks John, I finally found your article in the Google groups under
>"Diagnosing a generator problem - HELP!" after searching on your name.
>
>Can you tell me how the capacitor is connected in the stator please? I'm
>assuming it's in parallel with one of the stator coils and forms a tuned
>circuit to govern the output frequency?
It's a separate winding in the stator. The voltage is generally quite high - 250 or
more. It's strictly a parallel LC circuit.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
time. -Robert Half
Classic-Car-World Ltd
checked it with a DVM I get a momentary short circuit reading and then it
returns to about 56 Ohms. I would have thought it should have returned to a
value much greater than this? I've ordered a replacement capacitor of the
same value and voltage to see if this makes any difference.
Many thanks
Tom
"Neon John" <n...@never.com> wrote in message
news:4i4gn3tiidlaaqc51...@4ax.com...
Gordon Richmond
>checked it with a DVM I get a momentary short circuit reading and then it
>returns to about 56 Ohms. I would have thought it should have returned to a
>value much greater than this? I've ordered a replacement capacitor of the
>same value and voltage to see if this makes any difference.
>
>Many thanks
>
>Tom
Tom, if you have a capacitor shunted by a resistance, and the winding would constitute a
resistnace, that's the sort of reading you would expect from an ohmmeter. An initial very
low reading, as the capacitor charges up to the voltage level provided by the meter, then
it will read the resistance of the shunt.
You'd have to disconnect one end of the capacitor from the winding in order to thoroughly
check it, but my hunch is that your problem does not come from the capacitor; it appears
to be acting as a capacitor does.
Check your diodes with the ohmmeter. They should show a fairly low value with the leads
connected one way, and a very high value (ohms) with the leads reversed. Very high (both
ways) means an open diode; very low (both ways) mean a shorted one.
Hope this helps,
Gordon Richmond
Classic-Car-World Ltd
the gen set and on the bench when I checked it. I've also checked the
exciter windings which the capacitor connects to when the capacitor was
removed and these show about 10 Ohms.
I will need to disconnect the diodes on the rotor in the morning to check
these and will report back with my findings.
Thanks again
--
Tom
"Gordon Richmond" <rich...@telusplanet.net> wrote in message
news:3u6gn35ioo83tccj0...@4ax.com...
Neon John
<enqu...@classic-car-world.co.uk> wrote:
>Thanks John, I suspect the capacitor at the moment. I've removed this and
>checked it with a DVM I get a momentary short circuit reading and then it
>returns to about 56 Ohms. I would have thought it should have returned to a
>value much greater than this? I've ordered a replacement capacitor of the
>same value and voltage to see if this makes any difference.
That cap sounds maybe OK, if you meant 56k instead of 56 ohms. Motor run caps like
that commonly have an internal bleeder resistor. You should see the ohmmeter kick
toward zero ohms and then drift back to the value of the bleeder. 56kohms is about
right for a bleeder.
Can you run the generator? If you can, measure the voltage across the cap. If the
cap is bad or leaky, the voltage will be below about 150 volts, usually way below. If
the cap is good then the voltage is typically 250 volts or more. If you can measure
frequency, the frequency will be the 3rd harmonic of whatever speed your generator is
running at. If the cap is bad the frequency will be primarily the fundamental, 50 or
60 hz, depending on where you live.
The generator may not build any voltage at all if the cap is bad. If it doesn't then
hook a 12 volt car battery through a 120 volt, 100 watt lightbulb to the generator's
output. That'll supply enough field to get it to come up and if it happens to come
up to full voltage, the 100 watt bulb will protect the battery.
BTW, that's a standard motor run cap so you can pick up one at any appliance parts
store, HVAC supplier or electric motor repair shop. If they see you coming, it'll be
$30-40. If they give you the normal "wholesale" price, figure $5 to 10.
You can substitute a plastic cap, polypropylene or whatever, of the same voltage and
capacity. Motor caps are no longer oil and paper. Inside the can IS a plastic cap.
They just put 'em in the cans so as not to confuse the HVAC parts changers. The can
is mostly hollow or oil filled.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
To have doubted one’s own first principles is the mark of a civilized man -Oliver Wendell Holmes Jr.
Neon John
>Check your diodes with the ohmmeter. They should show a fairly low value with the leads
>connected one way, and a very high value (ohms) with the leads reversed. Very high (both
>ways) means an open diode; very low (both ways) mean a shorted one.
The diode is connected directly across the field winding. It'll measure less than an
ohm either way. Normally the diode is soldered and cemented down securely because it
rotates at 3600 rpm. Practically impossible to remove without destroying the diode.
My method of checking the diode with the rotor out is to hold a tape degausser over a
pole piece, setting up a transformer, and measure the DC voltage across the diode.
Pretty much any DC means that the diode is probably OK.
If the rotor is in the generator then one can turn it until the rotor poles are
centered in the stator poles and then apply some AC to the output leads. 120vac
through a 100 watt lightbulb works. Measure the DC across the diodes as before.
You'll need a high quality meter like a Fluke that isn't affected by AC on the DC
scale.
Most of the time, if changing the cap doesn't bring the voltage back up, I just snip
out the diodes and replace 'em. Easier than doing a lot of testing. Not much else
to go wrong other than maybe a shorted or open main winding and I exclude that before
I crack the case.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Give Blood. 8 Billion Mosquitoes can't be wrong.
Classic-Car-World Ltd
60W lamp in series with the stator windings to try and induce an EMF in the
windings.
I then took the following measurements:
Exciter windings with the Capacitor removed (Test points A - B) = 2.46V AC
Exciter windings with the Capacitor installed (Test points A - B) = 0.93V AC
Rotor Windings with the Capacitor removed = 153mV DC (Test points A1 - B1)
and 174mV DC (Test points A2 - B2)
Rotor windings with the Capacitor installed = 1.42mV DC (Test points A1 -
B1) (1.94V AC) and 1.42mV DC (Test points A2 - B2) (up to 10V AC changing).
I suspect one of the Rotor diodes may be faulty as I get the same changing
readings on the same winding if I rotate the rotor 180deg.
I've also rechecked the capacitor with the DVM and it is only reading 56
ohms after the initial charge kick.
The following is a link to the test set up and how I believe the windings
relate to each other.
www.isbcs.co.uk/images/240v_Generator_Test_Configuration.jpg
I'm not sure about the orientation of the diodes as these will have to be
disconnected before I can check them.
As soon as I have disconnected and checked the diodes I will update the
list.
--
Kindest Regards
Tom
"Neon John" <n...@never.com> wrote in message
news:b8ggn3thi8cb7cpee...@4ax.com...
Neon John
so if there are any notes there I didn't see 'em. Tried Opera and Firefox.
That's odd behavior. Rotor diodes are a good suspect but I might also suspect at
this point a shorted turn in the stator. I'd do a couple of things. First, increase
the current input. When I recommended a 100 watt light bulb, I was thinking around 1
amp for our normal 120vac. If you had a 500 watt heater that you could put in
series, so much the better.
My other thought is, can you remove the stator from the rotor and test it separately?
In the motor shop I'd now move to the Baker Surge Tester
http://www.bakerinst.com/BakerWeb/Products/DR_3612_Overview_Specs.html
Unfortunately they've password protected their user manuals (!) so I can't send you
there to see how this test works. In a nutshell, the instrument "rings" the winding
with a high voltage pulse and analyzes its decay behavior. An OK winding will ring
for 3 or 4 cycles while a compromised/shorted winding will either not ring at all or
will damp down in one cycle.
If you have an O'scope then you can somewhat simulate this test by passing DC through
the winding and snapping open the circuit with a cap-shunted switch (same as old
points-type car ignition) while monitoring the winding with the scope.
We have another gadget called a core loss tester. This involves passing a couple of
loops of heavy cable through the stator and passing high current AC through it. An
AC buzz-box welder will do. Then we scan each stator bar looking for differences.
The instrument has a probe coil connected to a meter and headphones. The probe is
held over the stator and gradually moved around. Any variation in intensity
registers. A shorted turn will essentially eliminate the magnetic field. That area
of the stator will also get slightly warm from the circulating current.
I'm still not happy with that capacitor reading. 56 ohms is far too low for a
bleeder. I also don't think the meter would kick much initially with that little
resistance across it. Are you sure your meter is OK?
I normally don't suspect test instruments because they are so reliable but every
reading you reported below is highly abnormal. Do you have another meter you can
try? I've never seen a shorted rotor diode cause the excitation winding voltage to
be that low.
At this point, if your meter is OK then I'd probably pull the rotor and stator apart
and test each separately.
John
On Mon, 31 Dec 2007 13:47:52 GMT, "Classic-Car-World Ltd"
<enqu...@classic-car-world.co.uk> wrote:
>Hi Guys, I've done some testing this morning on the generator with a 240V
>60W lamp in series with the stator windings to try and induce an EMF in the
>windings.
>
>I then took the following measurements:
>
>Exciter windings with the Capacitor removed (Test points A - B) = 2.46V AC
>Exciter windings with the Capacitor installed (Test points A - B) = 0.93V AC
>
>Rotor Windings with the Capacitor removed = 153mV DC (Test points A1 - B1)
>and 174mV DC (Test points A2 - B2)
>Rotor windings with the Capacitor installed = 1.42mV DC (Test points A1 -
>B1) (1.94V AC) and 1.42mV DC (Test points A2 - B2) (up to 10V AC changing).
>I suspect one of the Rotor diodes may be faulty as I get the same changing
>readings on the same winding if I rotate the rotor 180deg.
>
>I've also rechecked the capacitor with the DVM and it is only reading 56
>ohms after the initial charge kick.
>
>The following is a link to the test set up and how I believe the windings
>relate to each other.
>
>www.isbcs.co.uk/images/240v_Generator_Test_Configuration.jpg
>
>I'm not sure about the orientation of the diodes as these will have to be
>disconnected before I can check them.
>As soon as I have disconnected and checked the diodes I will update the
>list.
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
If we aren't supposed to eat animals, why are they made with meat?
Classic-Car-World Ltd
no additional notes. It should just show the stator windings (two coils in
series) the exciter windings with the capacitor in parallel and the two
rotor windings which I have now updated to include the capacitor in parallel
with these and the diodes. Let me know if you want me to send this to you
directly via e-mail.
I've rechecked the capacitor with another DVM and I get the same readings as
before, 56 Ohms. I don't suspect my original DVM as I've had this for a few
years and it has never let me down yet.
I've removed the diodes from the rotor and they appear to be ok. Forward
bias on both diodes gives me about 143 ohms and infinity on the reverse
bias. The diodes also have a small ceramic capacitor in parallel with them
which I didn't see until I removed them from the rotor.
The capacitors do not register anything when checked with the DVM and I
assume these are ok. I can't work out the size of these from the markings
(V350K10) but I'm guessing either nF or pF. The diodes are not like any
other diodes I have come across and look more like two diodes in series on
the same body. There are two sets of numbers on these, one on each body
casing I9445-6 & I9433-6. Can you identify these from the numbers?
The rotor winding would also appear to be ok as both of these show about 3
ohms with the diodes removed.
I think I'm back to replacing the main Capacitor when it arrives, it was
ordered on-line over the weekend and should be with me later in the week.
Thanks again
--
Kindest Regards
Tom
"Neon John" <n...@never.com> wrote in message
news:jl6in395cgit1lhmv...@4ax.com...
Neon John
<enqu...@classic-car-world.co.uk> wrote:
>The capacitors do not register anything when checked with the DVM and I
>assume these are ok. I can't work out the size of these from the markings
>(V350K10) but I'm guessing either nF or pF. The diodes are not like any
>other diodes I have come across and look more like two diodes in series on
>the same body. There are two sets of numbers on these, one on each body
>casing I9445-6 & I9433-6. Can you identify these from the numbers?
No idea what those numbers are. I tried my usual SWAG and stuck the numbers into
Google. No hits that made sense.
>
>The rotor winding would also appear to be ok as both of these show about 3
>ohms with the diodes removed.
>
>I think I'm back to replacing the main Capacitor when it arrives, it was
>ordered on-line over the weekend and should be with me later in the week.
Yep, that's what I'd do next.
John
Classic-Car-World Ltd
replaced the capacitor on the generator today with a new one and fired up
the engine. The generator came up straight away and I got a good steady 240V
output.
--
Kindest Regards
Tom
Neon John
>Hi John, just to say thank you for yours and the groups input on this. I
>replaced the capacitor on the generator today with a new one and fired up
>the engine. The generator came up straight away and I got a good steady 240V
>output.
Great! Glad to hear.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Risk: $20 hooker, year old condom.
Tom Horne
> Hi John, just to say thank you for yours and the groups input on this. I
> replaced the capacitor on the generator today with a new one and fired up
> the engine. The generator came up straight away and I got a good steady 240V
> output.
>
--
Tom Horne
Classic-Car-World Ltd
week. I was sitting on my computer as I do one evening when everything went
black in the world around me. We had lost our mains supply to the complete
area and everyone was in darkness.
Well this was the moment I must have been waiting for!! I carefully ran down
the stairs with a cry of don't worry we have a Generator and proceeded to
the garage. A couple of minutes later we had lights running of extension
leads and at least we could see. The power was out for almost an hour but I
was quite smug in the thought that my back up plan had come into use so soon
after rebuilding the generator. I was like a dog with two tails!! :o)
Unfortunately the half cooked roast dinner in the oven had to wait until the
main power came back on. :o(
The next stage I think will be to install a socket via an isolator switch
which will enable me to isolate the lights circuits in the house from the
mains and plug the generator directly in to avoid the need to have lead
lamps and extension leads running everywhere.
Thanks again for everyone for their input in getting the generator up and
running.
--
Kindest Regards
Tom
"Tom Horne" <hor...@veriqrmzon.net> wrote in message
news:o0Xgj.177079$TO.67539@trnddc01...
Neon John
>Hi Guys, I've just had cause to put the newly rebuilt generator to work this
>week. I was sitting on my computer as I do one evening when everything went
>black in the world around me. We had lost our mains supply to the complete
>area and everyone was in darkness.
>
>Well this was the moment I must have been waiting for!! I carefully ran down
>the stairs with a cry of don't worry we have a Generator and proceeded to
>the garage. A couple of minutes later we had lights running of extension
>leads and at least we could see. The power was out for almost an hour but I
>was quite smug in the thought that my back up plan had come into use so soon
>after rebuilding the generator. I was like a dog with two tails!! :o)
>Unfortunately the half cooked roast dinner in the oven had to wait until the
>main power came back on. :o(
'Tis sweet, isn't it? Hope your neighbors saw the light which makes it even better.
I have my cabin set up with a manual transfer switch but still use a roll-out
generator, an artifact from before I retired and moved here to my mountain cabin
permanently. I didn't want a generator outside permanently where it could get
stolen.
Last August there was a scheduled outage that was supposed to be for 4 hours for a
substation upgrade but ended up stretching to over 15. We had warning so I rolled my
generator out, hooked up the cables (power and remote starter) and was ready. When
the lights went out, I threw the switch, hit the starter and viola! My lights and
most importantly, my AC and wellpump were back in action. Later that evening I DID
cook supper on my electric stove.
Next morning I went down to the general store for the morning chat'n'chew. I pulled
up on my electric scooter which was silent. I heard my loud-mouth neighbor running
his mouth to the proprietor, bitching about how that SOB neighbor of his was the only
place up there that had lights last night. I slipped through the screen door and let
it slam loudly behind me. Loud-mouth jumped and when he turned around he looked like
the cat caught in the canary cage. Had I bought the generator with a MasterCard, it
could have been
1 7kw generator $1,800
2 7 gallon tanks of fuel $50
Pissing off your neighbor Priceless!!!!!
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Classic-Car-World Ltd
mate up the road who had lights. He's a builder and he also had a generator
which he uses when he's on site. Everywhere else was flickering candles.
I've did have some comments from friends & neighbours but all in a friendly
banter sort of way.
Cheers
Tom
"Neon John" <n...@never.com> wrote in message
news:p9s4q3d1v0kjahbkr...@4ax.com...
(PeteCresswell)
>I heard my loud-mouth neighbor running
>his mouth to the proprietor, bitching about how that SOB neighbor of his was the only
>place up there that had lights last night.
Any chance it was the noise that he was spun up about? Or are
houses too far apart?
--
PeteCresswell
Neon John
No, mine is quiet enough to sit on and carry on a normal conversation. He's a
half-back (damnyankee that came to Georgia and then only made it half way back home
before stopping again) with a big mouth and lots of greed and envy. Always one of
those to spoil an othterwise nice community.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
I didn't claw my way to the top of the food chain to eat vegetables!