And big transformers can have insane L/R time constants, so big that's it's hard to measure the winding resistances in a practical amount of time.
Yes, large breakers are "line synchronized". The magic phrase is "point on wave controller". These devices supply close (or trip) pulses to the breaker with just the right advance time that actual contact closure occurs at the right time to ensure the smallest transient on the power system (for example). More complicated controllers can time the opening of breakers to ensure that the interrupting mechanism has sufficient dielectric strength when the current goes through zero, or close properly when the voltage on one side of the breaker is not a single frequency sinusoid.
yes, all the inductors have a 1 ohm in series along with the generators having a 1 ohm for each.
I do have a 1MEG R for DC bridge on the secondary side to make spice happy for measurement, that works fine. Using the DELAY parameter, it all works perfectly as expected, currents and voltages are where they should be.
I experimented with increasing the induction of the transformer, I was able to get it to work as far as the generators properly starting however, I found that was only true because the larger induction caused a lag long enough, basically the same as using the delay method. But with that way, I had very large currents, in the area of 600 to 1k amps when it should be no more than 30 amps for initial cap charge on the secondary side after the bridge.
If I put the setup back to using the DELAY it works fine.
I can't explain it and I most likely will never find the reason for it but I have a work around that I know produces correct results and I'll leave it at that for now. I have a small 3 phase transformer I have tested this with and it works as expected.
ALl this just to test the effects of grounding a Delta leg to study the effects of increased votlage on a DC BUS.
Thank you for your help. Jamie
How do you do all three phases?
The really big stuff uses nitrogen to blow out the arc.
Understood. I tried 3 sources connected both Y and delta attached to resistors connected both Y and delta. No problems. However, again, with resistors.
Are you trying to discover the delta-Y transformation ratios?
No, I was testing the effects of what happens to a 3 phase bridge with storage cap if one of the legs of the Delta side (secondary) would become shorted to ground.
For that I needed a 3 phase transformer and in the end I found what the big deal is here. Spice starts off with DC of the angle if not 0 degrees, what ever the DC is per angle etc. WHen dealing with a Delta on the scondary side, this was feeding back effects to the primary side and causing lots of current.
Normally the supply line along with current limiting fuses allow for sag, all you see is a drop in voltage for the initial start and everything goes back to normal after the start up mag flux is balanced.
But in this case it seems that spice keeps the offset constant though out the sim, I don't see it progressing back to the symmetrical position for the 120 and 240 phases.
No need to hang on this, Sim works fine using delays much like using synchronizing switches i guess.
Thanks Jamie
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