Two questions.
Can I just add an inductor in series to a transformer primary and secondary to increase the inductive reactance of both (rather than adding more turns)? Will this affect the voltage?? I wonder if adding an inductor and adding more turns would produce similar behavior in the circuit. What do you think.
I tried using my multi-meter to measure the inductance of a transfomer. How come I can't measure any, as if there is open connections. What's the proper procedure. Thanks.
Manny
It's a bad idea. The added external inductance would be equivalent to what's called *leakage* inductance, which is generally the bad kind. The other kind is *mutual* inductance, which is what causes transformer action. The mutual inductance is generally also what is seen as *magnetizing* inductance in a transformer.
Leakage inductance causes a voltage drop proportional to load and so causes the transformer's output voltage to deviate from the ideal transformation ratio.
A simple but fairly good model of a transformer consists of a leakage inductance term in series with the source, a magnetizing inductance term after that, in paralle, and an "ideal" transformer following that. If the leakage inductance approaches zero and the magnetizing inductance becomes very high, then the model approaches an ideal transformer, which is usually what you want.
Not sure why you can't measure your inductance. It might be relatively high and so may be off scale for the inductance meter built in to your DVM.
Regards,
Nick
Thanks for this important information. So what I should do instead is to increase the number of turns of both primary and secondary. For example.. the input is 9 volts, the output is 90 volts.. and there 10 turns at the primary and 100 turns at the secondary. What would happen if I'd increase the turns of the 10 to 50 (in the primary) and the 100 to 500 (in the secondary). I presume it would still output a voltage of 90 volts given a 9 volt input right. Also I presume the increase inductance can caused more current wasted right? So the bad effect of this is only current losses and nothing else unlike leakage inductance which can so distort the waveform. Agree?
I want to change the inductance because my circuit would take longer time for a certain cycle such that I don't want the increase current to destroy the components in my circuit.
Many thanks.
Manny.
(cut my earlier info)
That's right. The voltage ratio would stay the same, but higher magnetizing inductance would put less load on the source and make the transformer look more like an "ideal" transformer.
Well, I'm not sure what you're saying here. The increased inductance you described above is a *good* thing, in general. The increase you proposed earlier isn't good because it's just a series impedance that doesn't really change the transformer.
Increasing the turns of the transformer results in *less* wasted current. It won't distort the waveform either way.
Sorry, I'm not sure I follow--we may have a bit of a language barrier. When you speak of a longer time, are you referring to using the transformer for something other than transforming sinusoidal voltages & currents?
Regards,
Nick
Trimmed earlier stuff
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