This thread is devoted to the capacitive coupling effect of bifilar and overlay transformers at T=0
So to kick things off,i offer the following test and results.
The circuit is as below.
What we are looking at in the scope shots below,is a 200nS pulse across our bifilar wound coil,which has a winding ratio of 1:1,and wire of the same size and type.
With this type of transformer,we should never see a higher current flow through the secondary to that of the primary,but as you can see,that is not the case here. Here we see not only a far greater current value flowing through the secondary,but a voltage across the load/CVR series equal to that of the voltage across the primary coil.
This is not normal induction taking place here. This is capacitive charging from the primary coil to the secondary coil. The flow of current through the primary has very little to do with the induction of the secondary.
It would seem that the secondary is being induced via the electric field created by displacement current during the charging of the capacitance between coils. As can be seen in the scope shots,this results in far more power being dissipated through the secondaries circuit to that supplied to the primary coil.
If we look at scope shot 1,where CH4 is across our 10 ohm CVR,and CH1 is across the primary coil and CVR,you will notice something very odd with the current trace,and so,the current through the primary coil.
You will see that for the first 25nS,the current through the primary coil rises,but then starts to fall until reaching a 0 value at 100nS. For the next 50nS there is no current flowing through the primary coil,and thus no power being consumed. For the last 50nS,the current inverts,which would indicate power being returned to the source.
Now,if you look at the current trace in scope shot two(the secondary coil circuit),you will see no drop in current that reflects the current value through the primary coil. You will also see that the current flowing through the secondaries circuit is far greater than that flowing through the primary coil-even with the 63 ohm series resistor.
The last scope shot shows all four traces--voltage across the primary CVR series(yellow trace)current through the primary(dark blue trace) voltage across the secondary CVR series(purple trace),and current through the secondary circuit(light blue trace).
I will leave it up to you guys to calculate P/in and P/dissipated by the secondary circuit
Brad
Never let your schooling get in the way of your education.
Author
Topic: At T=0 (Read 8995 times)
