Ah! here we are then.... ok so the winding of extra wire onto the output stage of the giant transformer DID achieve results. The generator would be running full throttle and we were getting 65-70 amps out of the big tin box. Only trouble was the output of the gen was dragged right down to about 180 volts-not good. It seemed to cope ok though so we let it run on auto for a few days. Inverter would call for charge, autostart gubbins starts gen on diesel for a couple of mins the swithces to lard. Once inverter sees battery volts back up to preset level shut down is initiated - swithed onto diesel for a minute then stopped.
Here is the auto gubbins doing its thing.....
One day, after a few days we heard the gen running and noticed the load seemed to keep dropping out - ammeter swinging about and twitching and volts output also twitching about. Then it dropped to zero volts and just sat there revving....We had noticed that the gen was running pretty hard and the alternator would get HOT. Oooer!
We switched off and let the whole shebang cool down for a few hours. On starting up the AC voltage would not strike/excite - yikes. It would only strike up feebly When over revving the engine by manually yanking the throttle open - double yikes!
I dont have a tech manual for this unit but seem to remember thinking it was supposed to be brushless. Just in case it wasnt we decided to see if we could have a 'look in' to see if any magic smoke had been released from anywhere...
The top of its skull is removed - tis indeed brushless self-exciting. Speccybloke checked the diodes on the rotor, theyre ok.
SOOOOOO..... then we decided to read up stuff about ac generators and self-excitation and discovered a whole world of arcane sparky knowledge that scared the bejeseus out of me! Seems we had allowed the required tiny amount of magnetism in the rotor to dissipate by allowing the voltage to be dragged down out of the 'sweet spot' around 230volts under heavy load....
ALSO we had no power factor correction installed on our charger. Running an inductive/reactive load (ie transformer) straight from an ac alternator is hideously fraught with back emf issues and extremely wasteful. We were losing 1kw of power between the gen output and the charger output. Mostly in the windings of our poor generator. Bah!
We tried manually remagnetising the rotor by 'flashing' 12v dc across the field windings to no avail.
We eventually managed to coax the generator back into life by revving it like mad to strike up then running it for a couple of hours a day with a 2kw heater attached. The plain resistive load has no power factor issues (look it up if you want - all nonsense!) so the gen could run at 230 volts and gradually reconditioned itself into a better place.
SOOOOOO.... then we thought - OK then lets correct the power factor to run this big transformer. This is done by fitting giant capacitors to the required value across the ac. At the same time we removed the extra windings to return our bad boy to standard.
Power factor correction crapacitors fitted....
Next time - er,
What happened next really....
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