help with genset 8/300

[penfold]

We need a picture of the rotor to judge what type it is, then we can start dealing with what's wrong. I doubt it's a PM rotor, although it's possible.

 

[stockers08]

https://www.google.co.uk/imgres?img...d=0ahUKEwicpqXrk_PKAhVCiBoKHeruAMUQMwgjKAQwBA

it looked similar to this. expect the lines were slanted /wrapping around

 

[stockers08]

View media item 8928View media item 8927View media item 8926
i popped to the garage and took these pictures of the rotor
on 1 end you can see there are no wires or diodes. the other is hard to see because the bearing plate and fan are still attached but it is identical to the
other end

 

[penfold]

It's a boggo squirrel cage rotor; it's as simple as an AC generator rotor gets. Unless you spin it so fast it falls apart there's nowt to go wrong. Let's have some piccies of the rest of the machine to see if there's owt obviously wrong.

 

[stockers08]

iv done a bit more research now i know what type of rotor it is. it just looks like its a lack of residual magnetism. and my flashing was lacking current to get thinks going. im going to attempt tomorrow with a car battery this time and have a load on the 240v line. (seperate 415 / 240 / 110 coils)

 

[stockers08]

ok i am stumped now. today was the first chance i got to go to the workshop. i bought myself a more sophisticated multi meter.
fired up the genset and i was getting 1.5v out of each phase. measured phase to phase. using a car battery, i flashed the stator using the welder output side. this made the voltage rise to 4-5v for a split second. i then had only 0.8v output. i flashed it again and got 0.09v if i left it to sit for 10 mins then fire it back up, i would get about 1v again. any suggestions?

 

[penfold]

What resistance are you getting on the stator coils and are they more or less equal? Assuming everything is as it should be I'd be tempted to try flashing it momentarily while it's running. Rubber gloves and stand on some rubber mat/wear wellies when you're doing it though!

 

[stockers08]

im getting 0.9 ohms on all coils. why the mat and gloves for 12v? i was doing that today. flashing with 12v while running and while stopped.

 

[the snooper]

I had this problem on a 5kva diesel tried various tools and nothing everything tested ok in the end I stuck my 3hp compressor on it which I knew it would not run, fluke or not it threw a wobbler and sprung to life.

 

[the snooper]

im getting 0.9 ohms on all coils. why the mat and gloves for 12v? i was doing that today. flashing with 12v while running and while stopped.

If it had of worked it would have put 240 out

 

[stockers08]

i had the ending going full chat but that did nothing but smoke me out. i seen a max of about 1.7v like this. im wondering if it would be worth getting a low voltage ac transformer, connecting it to the low voltage side of the stator (welder 32v max) via a 10a fuse. im thinking it would be better using ac as this is what the generator produces. i read online people using induction motors as generators. and having to power them up on the mains as a motor, before they would start working as a self excited generator.

 

[penfold]

why the mat and gloves for 12v?

To avoid death through electrocution mainly; if it starts generating you will be on the end of 240V. Do you have anything with an induction motor in, as that's what Snooper's compressor has?

How is it generating the various voltages? Are there different windings for 415, the welder etc?

 

[stockers08]

yes there is 3 phase star for welder 2 coils for 110 (centre tap) then 3 phase star for 415. im not sure yet if the 240 is seperate or taped
onto a 415 leg. i dont have any kind of motor avalibe other than a drill. but i know that wont work in terms of spinning the drill as it has
electronic speed control. so the power wont back feed from it

 

[stockers08]

yes full chat means full throttle. the throttle arm on the side of the engine at its stop point. i measure the frequency of the 1v output with the engine
running full chat and i was getting 79hz so obviously going faster than it should need to be going to make 240v

 

[stockers08]

oh when i was trying to flash it on the welder coils, i tried with with and without a 2.3kw fan heater as a load.

 

[stockers08]

tried revving to just over 4000prm (didnt want to go any higher) still no improvement.

 

[stockers08]

i tried with an angle grinder, then a 1200w fan heater. but i think i have just figured something out. the only thing flashing has done is to reduce the voltage from 1.5v to 0.7v or lower. i have a spare rotor here and i knew it had hardly any magnetism. so i arced a car battery across either end. it now has a much stronger magnetic field. (with battery removed of course) it has an effect of a compass from 6 inches away. where as before it only effected the compass at 1cm away. i might try this on the rotor in the generator. im thinking it will add enough magnetism to get things going

 

[stockers08]

nope, that didnt work. can a capacitor read as good on a tester, but actually be bad? causing the voltage not to rise..

 

[Ghilley]

IV got the same unit and same problem did this one get sorted ???