STC-10 AVR and capacitors

[BruceM]

I'm glad you posted about your AVR project, 12gauge.  You really did a great job.  You would have been done a lot sooner if I hadn't given you a bum steer with my first alternate power transistor choice, glad you called so I could look again and find a better match.  The circuit design is very simple and must have a "logic level" (low voltage) gate on the IGBT or start up/shut down will make pop and smoke.

Oiler, if you're still with us, did you get your regulator?  Since the start of this thread, waveforms shown us by RCAvictim have confirmed that the 3 phase ST heads DO NOT have the "harmonic hump" waveform distortion.  Depending on the ST head, it may have the "ratcheting" which can include some nasty spikes on the waveform peak.  (RCAvictims 3 phase head didn't have this- his output is very nice quality.)

12gauge had those same spikes on the peak of his waveform, and was able to tame them with 50uF motor run cap across the line AC which was called for in his inverter/charger manual,  as I recall.  They were causing his inverter/charger to sense overvoltage and not accept his AC.  I don't know if 50 is the minimum that would work, or that's just what he used as the charger called for it.

Once again, bravo 12gauge, please show us your new scope shots of pre and post capacitor! (I've seen them but they're not mine to make public.)

Best Wishes,
Bruce

[oiler]

Yes, i'm still here.
No, I,ve had too much to do,but by accident I came up vith another soulution.

The generator runs our freezer, refigerator and dryer. The rest is powered from the grid.
I,m heating a 1200 litres water tank as usual from the engine and added a 2 kw submerged heater to keep engine load high enough.
With these loads the 6/1 consumes 24 litres wvo in 24 hours and we have a warm hous and lots of hot water.

This is indeed a good way to keep SWMBO happy

What bothers me though, is, that I must turn the heater off before she turns her clothesdryer on.
Could have been fun to have some sort of auto sensing devise to keep engine loaded.

BTW. My engine has broken a camshaft gear taper pin at 1158 hours of operation

[BruceM]

Sorry about your camshaft pin, Oiler.  Guess they "made it fit" in Rajkot once again.  Hopefully someday soon John will have quality camshafts available for the 6/1's. Was increasing the load the solution for making the "buzz" on appliances go away?

[12gauge]

Here's some oscope pictures of my power produced with the regulator.  The first 2 are without any capacitor on line.  In the reduced view you can see the spikes on each peak.

http://picasaweb.google.com/lh/photo/cBKA2jvOjRp_NXBwLLqA8A?authkey=Gv1sRgCOG40tbTq4KcAw&feat=directlink

http://picasaweb.google.com/lh/photo/8c1e8kH0lCQh0jXZ0f1mFQ?authkey=Gv1sRgCOG40tbTq4KcAw&feat=directlink

The next 2 are with the 50 uf capacitor on line.  The inverter/charger would accept this.  I plan to do more fine tuning, if possible, later.

http://picasaweb.google.com/lh/photo/y_CW2_uBSHXXEaJEnWBNxA?authkey=Gv1sRgCOG40tbTq4KcAw&feat=directlink

http://picasaweb.google.com/lh/photo/FVxDraw8p3lNHD9ZazRMcw?authkey=Gv1sRgCOG40tbTq4KcAw&feat=directlink

Also, since the oscope is a new toy for me, I had to look at some other things.  Here is what my inverter power looks like.

http://picasaweb.google.com/lh/photo/MnmY7M9MLA9OlbOKL0ymnw?authkey=Gv1sRgCOG40tbTq4KcAw&feat=directlink

I've learned a lot and been having great fun doing it.  Thanks again to all who contributed.

73, RH

[oiler]

Bruce...

No. They still buzz, but we can live with it.

It is more imprtant for the wife to be able to run the stove, washer , dryer and wacuumcleaner at the ame time

[12gauge]

oiler,
Have you or can you view your power with an Oscope?  It would be interesting to see it.
RH

[oiler]

It sure would, but I haven,t found one yet.

This weekend I,m hoping to have time to fix the camshaft.

[yellowhead]

I just ordered one of the ST AVRs from Tom at Central Georgia Diesel. He was most helpful and included a wiring diagram for using the unit without the harmonic winding as has been suggested earlier in this discussion.

In essence, the AVR appears to sense voltage between L1/L2 and then supplies excitation to the field winding by series regulating between N/L1 and the rectifier. This looks very similar to the approach taken by BruceM's AVR although in his circuit it is the rectified AC that is being regulated. Not sure how the Chinese unit is doing its job but Tom suggests that it has worked fine on a variety of ST heads.

Regardless, my concern in both cases is what happens in the event of a failure causing the full rectified 120V to be applied to the field? No doubt field current will cause the suggested 5A fuse in BruceM's circuit to blow before the field winding is toast.  I think I'll include something similar with the Chinese unit. Before that happens though I'm guessing the output voltage will spike quite a bit. Am I right? Any idea how much? I don't want to damage any household loads or (worse) the inverter ...

I'll post some before and after pictures of the AC waveform when I have this hooked up but in the meantime I thought I'd better ask about this as it might be a bit of a safety issue.