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While the multiple wire thing is OK, let us say I want to generate 100Amps RMS.
I like the short circuiting the secondary of a transformer and using it as a reverese CT thing but please help me with the math a bit.
Aim: To get 100A rms pure sinusoidal current through a conductor.
Ferrite core transformer: 100 turns primary and 1 turn secondary. So 12Volts applied to the primary will give 0.12V or 120mV output.
We must provide a very small impedance to the output (basically close to a short circuit) such that it draws 100A when provided with 120mV. i.e. 1.2mohm impedance. Most probably even a short circuit will not allow such a small impedance and so Primary voltage will have to be increased till we get 100A output.
Problem: As the primary will be excited by SPWM, to get a sinusoidal current at the output, the equivalent impedance of the secondary, primary, leakage reactances etc must have a dominating inductive component to filter out the switching frequency which I'm planning to have around 10-15kHz at the moment.
Do you guys thing this will naturally be the case? If not will providing small air gap which would increase leakage reactances X1 and X2' make the equivalent inductive without leading to other issues?
The SPWM will be bipolar (half bridge or push pull) so saturation should not be an issue.
The overall power requirement is not high, and your idea of a portable battery powered 100A current calibrator instrument would be quite practical.
It seems to me that you are disproving a number of points that won't be actually considered for a serious design.An off the shelf CT may be problematic...
That's all very true.I was talking about a CT with sufficient VA rating for a reason. 50 Hz current transformers have clear specifications, you can well calculate the saturation margin in this application. Obviously I'm not suggesting a high frequency CT.
Oops, you are absolutely right.impedance is transformed by turns ratio squared....
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