[TCML] MOT Measurements

[Finn Hammer]

This is getting more and more interesting.
To me, the news is the variation in leakage inductance with input voltage.
Back when I ran simulations with these transformers, I measured the 
inductance of the primary, then calculated the secondary inductance and 
plugged them in microsim.
After that, I would adjust coupling until the model delivered the same 
current  into a short, as the real thing did.
Of course, Microsim supplied a leakage inductance that fits in the 
process, so resonance at full input voltage wouls be modelled faithfully.
I never interested in the low voltage situation, but maby this explains 
why the coils seem to "kick in" when the variac gets turned right up?

Cheers, Finn Hammer

bartb skrev:
> Hi All,
>
> I hope I'm not boring you with this (I'm sure some are). But I think 
> the next step is to look at a 15/30 NST which has not been modified. I 
> have a couple on hand (Franceformers). I have a "gut feeling" that we 
> really don't know where shunted transformers (NST's, MOT's, etc.) are 
> truly at. Some resonant charging may or may not be occurring with our 
> tank cap values. All the programs (including my own Javatc) are 
> looking at Cres of non-shunted transformers. The shunted transformer 
> is a different beast and without measurements, only guesses.
>
> These transformers force leakage inductance via the shunts to apply 
> regulation. This changes the transformer as we assume it to be as far 
> as currents, voltages, Cres, etc. The load also changes the output. 
> NST's will begin to suffer a voltage drop even with a small load. 
> MOT's are current beasts, and they will require larger loads before 
> significant change in output voltage is seen. Load impedance of 
> shunted transformers is yet another set of tests that should be 
> performed at some point.
>
> I'll run through my normal 10V increment routine with one of my 
> 15/30's. I'll set a variac to as near 10V as I can get, then measure 
> the open and short circuit primary currents as well as open secondary 
> voltage. Then head up to 20V and do all again. This is my routine as 
> it keeps the source voltage unchanging, and thus, the numbers for Ioc, 
> Isc, Vin, and Vout are all in very good agreement. My plan is to first 
> do this unloaded (basic transformer testing). But loading is yet 
> another issue.
>
> If anyone has any additional thoughts, please let me know. For the 
> NST, considering it's low power, I can will also measure true power as 
> well as VA.
>
> Best regards,
> Bart