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Author Topic: Flashing an Alternator help request  (Read 5259 times)

guest23837

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Flashing an Alternator help request
« on: May 24, 2018, 09:54:49 PM »
Does anyone have an idiots guide to flashing a generator alternator? Thank you

dieselgman

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Re: Flashing an Alternator help request
« Reply #1 on: May 24, 2018, 10:27:29 PM »
Each generator type will have specific instructions and they are variable depending on the specific design.

In general you have to apply a low voltage (6vdc) to your field windings to get the magnetism back. Once you have kick started the process, it will be self maintaining. If there is an AVR involved, you will need to remove it from the circuit during the flash to avoid damage. If your unit is "inherently regulated" as in Marathon LIMA MAC models, all you will need to do is momentarily short circuit the output windings while the unit is spun up to speed. Exact procedures are usually covered in the O&M manuals for your generator head.

If unfamiliar with the risks and the process,, get some help. Test your windings and components while you are at it.

dieselgman
« Last Edit: May 24, 2018, 10:33:14 PM by dieselgman »
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guest23837

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Re: Flashing an Alternator help request
« Reply #2 on: May 24, 2018, 11:12:24 PM »
Each generator type will have specific instructions and they are variable depending on the specific design.

In general you have to apply a low voltage (6vdc) to your field windings to get the magnetism back. Once you have kick started the process, it will be self maintaining. If there is an AVR involved, you will need to remove it from the circuit during the flash to avoid damage. If your unit is "inherently regulated" as in Marathon LIMA MAC models, all you will need to do is momentarily short circuit the output windings while the unit is spun up to speed. Exact procedures are usually covered in the O&M manuals for your generator head.

If unfamiliar with the risks and the process,, get some help. Test your windings and components while you are at it.

dieselgman
So I disconnect the AVR and apply voltage to the wires connected to the coils? Do I do this with the engine running? Do I need to disconnect and isolate the coils prior to flashing?

guest23837

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Re: Flashing an Alternator help request
« Reply #3 on: May 24, 2018, 11:14:17 PM »

I always did it from a 12V battery with the AVR but no loads connected. Maybe I was lucky?

Did do it while it was running though. Generally with a volt meter on the output you will see the voltage building over a few seconds and then it will come up.
I can always tell when the field has been restored by the electrical hum that I can somehow manage to hear over the clatter of the engines.  Petrols are harder to hear than diesels, must be the respective Frequencys.

What I have also done ( this is a confession NOT a recommendation) is just give the things some real big revs. That seems to create stronger fields with whatever magnetism there is left ( logically) and many times I have got away with that.
I had a genny that would always  be dead after I brought it out after a few months but warming it up and bypassing the governor on the carb to give it a few big hits always brought the thing back to life with no other tinkering required.
How do I know where to connect each wire? there are 4 in total... IDIOT doing this mr Glort

dieselgman

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Re: Flashing an Alternator help request
« Reply #4 on: May 25, 2018, 02:15:54 AM »
Lacking the information on what generator head you have installed, exacting instructions cannot be determined. If you have an AVR on your unit, then disconnect F+ and F-, pay close attention to polarity and apply battery voltage here (to the leads going back to your windings) Not to the AVR. Be certain that you do not reverse polarity! I generally start with a 6 volt dry-cell battery and just apply that voltage for a short time without rotation of the generator. In some cases this will restore enough magnetism to start the head the next time it is run and this provides the maximum level of safety for your components and yourself. On sets with no AVR, you will need to apply the same DC voltage to the same portion of your windings, but the wiring is different and will require specific knowledge of your connections. You DO NOT do this to the main generator windings and NOT during operation of the machine. The only exception I know for sure will be the brushless Marathon "inherently regulated" heads. Most modern heads have AVRs or other feedback devices (capacitors or transformers) used to vary the excitation voltage.
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mike90045

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Re: Flashing an Alternator help request
« Reply #5 on: May 25, 2018, 06:01:38 AM »
when you get it working, never leave a load connected when shutting down, that's one way to de-mag the rotor

guest23837

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Re: Flashing an Alternator help request
« Reply #6 on: May 25, 2018, 08:34:28 AM »
Thanks guys I will play around with it today. I have other generators and thanks to mr Glort am on the way to building a low speed 12v system as well but a Yanmar generator for €50 appeals to me. I know I could sell the engine on it's own for 8-10 times what I paid for it but where's the fun in that? A new 5 Kv brushless AVR alternator is €400 again no fun in that either!

guest23837

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Re: Flashing an Alternator help request
« Reply #7 on: May 25, 2018, 10:03:21 AM »
I have tried to flash the generator with no result I connected a volt meter and it's showing 4 volts however if I connect the battery to F1 and F2 red and black wires the voltages rises and then falls back. Could it be the AVR? If I'm getting 4 volts does that mean it's producing power and doesnt require further flashing? There is no power at the brushes I'd have expected a few volts there??? I wish Id have went to school on days like this!

EdDee

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Re: Flashing an Alternator help request
« Reply #8 on: May 25, 2018, 02:00:56 PM »
Hi JD,

The brushes are the input to the system to "assist excite" the rotor/armature - There is a feedback from one of the field windings to the AVR that gets rectified and pushed back into the rotor to get the output voltage to spec. It defs looks like the AVR is at fault/suspect here, juice the brushes with about 12VDC nominal and check your output terminal voltages, if they are LOWER than rated, you are fairly safe to continue. Then check any additional inputs into the AVR, there are usually at least one, sometimes two or even three pairs of wires coming back to it. If there are no voltages coming in to the AVR, shut down the unit and disconnect the AVR completely and try again. Still no voltages, then you might have lost or burnt one of the windings. If there are voltages present, above 20V nominally that is, then there is pretty much a certainty that the AVR itself is fried, a common occurrence....

In my limited experience with these creatures, the voltages to/from the AVR/Connectors are
(a) a "driver" output from the windings going into the AVR that gets regulated and fed back to the brushes to maintain output voltage
(b) a "sensing" voltage that is of fairly low current to power the AVR and used to "sense" the output of the main terminals for a control of the output voltage
(c) The regulated output from the AVR which goes to the brushes derived largely from (a)

Note: some AVR's have 2, 4 or 6 wires input as well as the 2 wires out to the brushes...

A brief way I understand them:
2 wire input AVR - a+b above are combined, still has c
4 wire input AVR - as above (most common around my neck of the woods)
6 wire input AVR - as above but sensing and supply are split, still has c - ie 2 sensing wires, 2 supply wires to power AVR, 2 "power wires" to be rectified, regulated and fed back to the brushes via (c)

This is all excluding the 2 or 4 or 6 "output" wires that go to the outside world to run your electrical doo-dahs....

A pertinent question though... with the AVR disconnected, the output wires disconnected and the unit not spinning ie just with the genhead electrically isolated from the rest of the world, have you checked for continuity of the windings and also that none of the windings are shorted to ground? (all winding resistances should be fairly low, in the region of less than 1000 ohms and all windings should have a resistance of greater than 100 000 ohms when measured between coil and chassis.)

If not - time for a re-wind!

Hope this helps

Cheers
Ed
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guest23837

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Re: Flashing an Alternator help request
« Reply #9 on: May 25, 2018, 03:50:15 PM »

You are getting 4 Volts at the outlet?

Yes on the 230 outlet I don't have a 110 plug

guest23837

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Re: Flashing an Alternator help request
« Reply #10 on: May 25, 2018, 03:53:19 PM »
Hi JD,

The brushes are the input to the system to "assist excite" the rotor/armature - There is a feedback from one of the field windings to the AVR that gets rectified and pushed back into the rotor to get the output voltage to spec. It defs looks like the AVR is at fault/suspect here, juice the brushes with about 12VDC nominal and check your output terminal voltages, if they are LOWER than rated, you are fairly safe to continue. Then check any additional inputs into the AVR, there are usually at least one, sometimes two or even three pairs of wires coming back to it. If there are no voltages coming in to the AVR, shut down the unit and disconnect the AVR completely and try again. Still no voltages, then you might have lost or burnt one of the windings. If there are voltages present, above 20V nominally that is, then there is pretty much a certainty that the AVR itself is fried, a common occurrence....

Hope this helps

Cheers
Ed

By lower than rated do you mean lower than 230 or 12 v? Thanka

guest23837

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Re: Flashing an Alternator help request
« Reply #11 on: May 25, 2018, 05:08:43 PM »
Hi JD,

The brushes are the input to the system to "assist excite" the rotor/armature - There is a feedback from one of the field windings to the AVR that gets rectified and pushed back into the rotor to get the output voltage to spec. It defs looks like the AVR is at fault/suspect here, juice the brushes with about 12VDC nominal and check your output terminal voltages, if they are LOWER than rated, you are fairly safe to continue. Then check any additional inputs into the AVR, there are usually at least one, sometimes two or even three pairs of wires coming back to it. If there are no voltages coming in to the AVR, shut down the unit and disconnect the AVR completely and try again. Still no voltages, then you might have lost or burnt one of the windings. If there are voltages present, above 20V nominally that is, then there is pretty much a certainty that the AVR itself is fried, a common occurrence....

In my limited experience with these creatures, the voltages to/from the AVR/Connectors are
(a) a "driver" output from the windings going into the AVR that gets regulated and fed back to the brushes to maintain output voltage
(b) a "sensing" voltage that is of fairly low current to power the AVR and used to "sense" the output of the main terminals for a control of the output voltage
(c) The regulated output from the AVR which goes to the brushes derived largely from (a)

Note: some AVR's have 2, 4 or 6 wires input as well as the 2 wires out to the brushes...

A brief way I understand them:
2 wire input AVR - a+b above are combined, still has c
4 wire input AVR - as above (most common around my neck of the woods)
6 wire input AVR - as above but sensing and supply are split, still has c - ie 2 sensing wires, 2 supply wires to power AVR, 2 "power wires" to be rectified, regulated and fed back to the brushes via (c)

This is all excluding the 2 or 4 or 6 "output" wires that go to the outside world to run your electrical doo-dahs....

A pertinent question though... with the AVR disconnected, the output wires disconnected and the unit not spinning ie just with the genhead electrically isolated from the rest of the world, have you checked for continuity of the windings and also that none of the windings are shorted to ground? (all winding resistances should be fairly low, in the region of less than 1000 ohms and all windings should have a resistance of greater than 100 000 ohms when measured between coil and chassis.)

If not - time for a re-wind!

Hope this helps

Cheers
Ed

Hi Ed,
Thank you for the explanation! I tried your suggestion and connected the brushes to a small 4 am battery charger. The voltage rose to 150 volts and stayed there. Is this about right? I only ran it for 30 seconds but thats huge progress for me! I assume your diagnoses of the AVR is correct. The AVR I ordered has arrived it's got the wrong plug and is 2-3 KV on the box so I assume it's useless? I wouldn't know which wire went where if I cut the plug off as the colours are different. I will have to order another one, Grrr
Thanks again
Paul

guest23837

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Re: Flashing an Alternator help request
« Reply #12 on: May 25, 2018, 05:11:11 PM »
Lacking the information on what generator head you have installed, exacting instructions cannot be determined. If you have an AVR on your unit, then disconnect F+ and F-, pay close attention to polarity and apply battery voltage here (to the leads going back to your windings) Not to the AVR. Be certain that you do not reverse polarity! I generally start with a 6 volt dry-cell battery and just apply that voltage for a short time without rotation of the generator. In some cases this will restore enough magnetism to start the head the next time it is run and this provides the maximum level of safety for your components and yourself. On sets with no AVR, you will need to apply the same DC voltage to the same portion of your windings, but the wiring is different and will require specific knowledge of your connections. You DO NOT do this to the main generator windings and NOT during operation of the machine. The only exception I know for sure will be the brushless Marathon "inherently regulated" heads. Most modern heads have AVRs or other feedback devices (capacitors or transformers) used to vary the excitation voltage.

Hi G man
I think the alternator is a Markan but not entirely sure. Thanks to Ed I now have 150 volts so I will order another AVR as the last one has the wrong plug and the wrong rating.
Thanks for your help, as usual this site is gold !

guest23837

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Re: Flashing an Alternator help request
« Reply #13 on: May 25, 2018, 08:54:49 PM »
Lacking the information on what generator head you have installed, exacting instructions cannot be determined. If you have an AVR on your unit, then disconnect F+ and F-, pay close attention to polarity and apply battery voltage here (to the leads going back to your windings) Not to the AVR. Be certain that you do not reverse polarity! I generally start with a 6 volt dry-cell battery and just apply that voltage for a short time without rotation of the generator. In some cases this will restore enough magnetism to start the head the next time it is run and this provides the maximum level of safety for your components and yourself. On sets with no AVR, you will need to apply the same DC voltage to the same portion of your windings, but the wiring is different and will require specific knowledge of your connections. You DO NOT do this to the main generator windings and NOT during operation of the machine. The only exception I know for sure will be the brushless Marathon "inherently regulated" heads. Most modern heads have AVRs or other feedback devices (capacitors or transformers) used to vary the excitation voltage.
Hi Gman
It seem the AVR is the problem as I'm getting some power from the outlet. I ordered a new AVR they sent the wrong one it's smaller has a different plug and is rated 2-3 kv so I assume it's useless?As you probably know I avoid wires and electricity Id be reluctant to cut the plug off as the wires are a different colour and I have no idea where they go.
Thanks for replying I might get this fixed yet!

guest23837

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Re: Flashing an Alternator help request
« Reply #14 on: June 06, 2018, 12:44:58 PM »
All sorted new avr new brushes and a LOT of help from you guys. Many Thanks